Investigating intraindividual pain variability: methods, applications, issues, and directions

Neuroticism is Associated With Greater Affective Variability at High Levels of Momentary Affective Well-Being, but With Lower Affective Variability at Low Levels of Momentary Affective Well-Being

OBJECTIVE

Research challenged the notion that neuroticism correlates with affective variability, suggesting that it may result from statistical artifacts due to the non-normal distribution of negative affect. We aim to advance this line of research by (a) introducing affect balance as a normally distributed measure of affective well-being and (b) examining current affect balance as a moderator of the relationship between neuroticism and affect balance variability.

METHOD

We meta-analyzed the results of 14 ambulatory assessment datasets (N = 2389 participants, N = 174,423 observations).

RESULTS

We found that while the associations between the mean and affective variability were large for negative affect, they were much smaller for affect balance. Moreover, the association between neuroticism and variability in negative affect was very small, yet medium-sized for affect balance. Importantly, the latter association depended on current affect levels: Participants high relative to low in neuroticism showed stronger subsequent fluctuations in affect balance when currently feeling better than usual, but weaker subsequent fluctuations in (and thus more persistent) affect balance when currently feeling worse than usual.

CONCLUSION

Increased variability should not be seen as a bad sign but may be a sign that an affective system is changing, which may be adaptive or maladaptive for an individual, depending on the initial state of the system.

Using intensive longitudinal assessment to study mechanisms of the Native American pain inequity among persons experiencing depression and/or anxiety: The role of interpersonal discrimination and stress

Native Americans (NA) experience higher rates of chronic pain than other U.S. racial/ethnic groups. Our research has indicated discrimination and stress play a role in chronic pain onset. However, chronic pain research has mostly relied on retrospective reports that may be impacted by recall bias. The current study was a secondary analysis of data from 208 NA, 206 Black, 202 Latinx, and 206 non-Hispanic White (NHW) participants from an efficacy trial of a mobile health intervention for depression and anxiety. Participants were prompted to complete 6 months of twice daily ecological momentary assessments (EMAs) that included stress and pain. Discrimination was assessed at baseline. Pain EMAs were used to reduce recall bias and estimate chronic pain prevalence. Dynamic structural equation modeling assessed the impact of race/ethnicity and discrimination on stress-pain relationships, as well as pain and stress dynamics. To assess chronic pain (pain ≥3-months), participants had to complete ≥3-months of consecutive EMAs, leaving 578 participants available for primary analyses (there were no racial/ethnic differences in EMA completion). Results showed NAs had the highest rate of chronic pain that was statistically significantly higher than NHW and Black participants. Controlling discrimination eliminated the NA-NHW, but not the NA-Black, pain inequity. Moreover, a reciprocal stress-pain relationship was found and was stronger in NAs than other groups. Discrimination did not exacerbate stress-pain relationships but was associated with higher rates of chronic pain and greater pain fluctuations, regardless of race/ethnicity. These findings indicate that targeting stress and discrimination could help reduce the NA pain inequity. PERSPECTIVE: Native Americans experienced a self-reinforcing stress-pain cycle in which stress predicted future pain and pain predicted future stress. This cycle was stronger than Black, Latinx, and non-Hispanic White groups. Discrimination was associated with chronic pain but not stronger stress-pain relationships. These findings have implications for treatment.

The role of pain trajectory and sex in predicting postoperative neck pain in patients after cervical spine surgery: A retrospective cohort study

BackgroundPostoperative neck pain is common after cervical spine surgery, with potential progression to chronic pain.ObjectiveTo assess the role of pain trajectory in predicting postoperative neck pain following cervical spine surgery and to discern sex-based differences in this relationship.MethodsA retrospective study was conducted on 133 patients (mean age:64.1 ± 11.9 years; 86 males, 47 females) undergoing cervical spine surgery. Pain trajectory, defined by Numerical Rating Scale scores on postoperative days 1, 3, 5, and 7, was analyzed using hierarchical multiple regression to evaluate its predictive value for neck pain at two weeks, with sex as a moderator.ResultsSex (B = 0.613; p < .05), slope (B = 1.528; p < .01), and intercept (B = 0.410; p < .01) were significant predictors. Pain trajectory had a stronger association with neck pain in females (B = 2.283; p < .01) than in males (B = 0.772; p = .03).ConclusionPain trajectory is a predictor of postoperative neck pain and highlights sex-based differences. Incorporating pain trajectory monitoring into clinical practice can enable the early identification of patients at higher risk for poor pain outcomes, facilitating more targeted and effective interventions.

Assessing the predictive value of peak alpha frequency for the sensitivity to pain

ABSTRACT

Pain perception varies considerably between and within individuals. How the brain determines these variations has yet to be fully understood. The peak frequency of alpha oscillations has recently been shown to predict an individual's sensitivity to longer-lasting experimental and clinical pain. Peak alpha frequency (PAF) is, thus, discussed as a potential biomarker and novel target for neuromodulatory treatments of pain. Here, we scrutinized the generalizability of the relation between PAF and pain. We applied brief painful laser stimuli to 159 healthy participants and related interindividual and intraindividual variations of pain perception to PAF measured with electroencephalography. Comprehensive multiverse analyses replicated across 2 sessions did not provide consistent evidence for a predictive role of PAF for brief experimental pain. This indicates that the relationship between PAF and pain does not generalize to all types of pain and calls for a systematic exploration of the relationship between PAF, pain perception, and other neuropsychiatric symptoms. Such explorations help to understand the prospects and limits of biomarkers and might guide future research on biomarkers of pain and neuropsychiatric disorders.

A cross-cultural study translating and validating the COMPAT-SF pain questionnaire in Telugu, Bengali and Hindi

BACKGROUND AND OBJECTIVES

Chronic pancreatitis (CP) is a fibroinflammatory disease causing functional injury. Abdominal pain is the predominant symptom negatively impacting the quality of life. The Comprehensive Pain Assessment Tool (COMPAT-SF) questionnaire, designed and validated to assess pain in CP, was previously only available in English and Danish. Given the high prevalence of CP in India, translating and validating COMPAT-SF into different languages becomes crucial.

METHODS

The COMPAT-SF underwent translation into three Indian languages (Hindi, Telugu and Bengali) and was back-translated to English to ensure cross-cultural equivalence. Validation was conducted at two tertiary care centers in India. As Hindi is the most widespread language, bilingual CP patients answered the COMPAT-SF in Hindi and English at a three-week interval. All sub-group answers were compared with patient data from the US. Structural equation modeling and confirmatory factor analysis were employed for validation.

RESULTS

Total 64 patients (19 Hindi-speaking,15 Telugu and 30 Bengali) were included and compared with 91 English-speaking patients. Translation adequacy was confirmed with > 85% concordance. Despite modest Cronbach alpha values in reliability analysis, structural equation modeling demonstrated high consistency with the original COMPAT-SF study. Some cultural differences in responses were observed, but the responses were comparable overall. Confirmatory factor analysis on the pooled data indicated an acceptable model fit and the Hindi version showed good accordance with the English version.

CONCLUSION

The translated COMPAT-SF versions proved to be valid and reliable pain assessment tools for CP patients. The study underscores the importance of addressing pain comprehensively.

Pharmacological pain management in patients with rheumatoid arthritis: a narrative literature review

BACKGROUND

Pain is a major challenge for patients with rheumatoid arthritis (RA), with many people suffering chronic pain. Current RA management guidelines focus on assessing and reducing disease activity using disease-modifying anti-rheumatic drugs (DMARDs). Consequently, pain care is often suboptimal, with growing evidence that analgesics are widely prescribed to patients with RA, despite potential toxicities and limited evidence for efficacy. Our review provides an overview of pharmacological treatments for pain in patients with RA, summarising their efficacy and use.

FINDINGS

Thirteen systematic reviews of drug efficacy for pain in patients with RA were included in this review. These showed moderate- to high-quality evidence from clinical trials in more contemporary time-periods (mainly 1990s/2000s for synthetic DMARDs and post-2000 for biological/targeted synthetic DMARDs) that, in patients with active RA, short-term glucocorticoids and synthetic, biologic, and targeted synthetic DMARDs have efficacy at reducing pain intensity relative to placebo. In contrast, they showed low-quality evidence from trials in more historical time-periods (mainly in the 1960s-1990s for opioids and paracetamol) that (aside from naproxen) analgesics/neuromodulators provide any improvements in pain relative to placebo, and no supportive evidence for gabapentinoids, or long-term opioids. Despite this evidence base, 21 studies of analgesic prescribing in patients with RA consistently showed substantial and sustained prescribing of analgesics, particularly opioids, with approximately one quarter and > 40% of patients receiving chronic opioid prescriptions in each year in England and North America, respectively. Whilst NSAID prescribing had fallen over time across countries, gabapentinoid prescribing in England had risen from < 1% of patients in 2004 to approximately 10% in 2020. Prescribing levels varied substantially between individual clinicians and groups of patients.

CONCLUSIONS

In patients with active RA, DMARDs have efficacy at reducing pain, supporting the role of treat-to-target strategies. Despite limited evidence that analgesics improve pain in patients with RA, these medicines are widely prescribed. The reasons for this are unclear. We consider that closing this evidence-to-practice gap requires qualitative research exploring the drivers of this practice, high-quality trials of analgesic efficacy in contemporary RA populations, alongside an increased focus on pain management (including pharmacological and non-pharmacological options) within RA guidelines.

Short-term Frailty Index Fluctuations in Older Adults: Noise or Signal?

BACKGROUND

Reversible short-term fluctuations in the frailty index (FI) are often thought of as representing only noise or error. Here, we assess (i) the size and source of short-term FI fluctuations, (ii) variation across sociodemographic characteristics, (iii) association with chronic diseases, (iv) correlation with age, frailty level, frailty change, and mortality, and (v) whether fluctuations reflect discrete health transitions.

METHODS

Nationwide, biweekly longitudinal data from 426 community-dwelling older adults (70+) were collected in the FRequent health Assessment In Later life (FRAIL70+) study using a measurement burst design (5 122 repeated observations, median of 13 repeated observations per person). We calculated the intraindividual standard deviation of the FI and used location-scale mixed regression models.

RESULTS

Mean intraindividual standard deviation was 0.04 (standard deviation = .03). Fluctuations were driven foremost by cognitive problems, somatic symptoms, and limitations in instrumental and mobility-related activities of daily living. Short-term fluctuations correlated with higher FI levels (r = 0.62), 1-year FI change (r = 0.26), and older age (+3% per year). Older adults who took to bed due to a health problem (+50%), those who had an overnight hospital stay (+50%), and those who died during follow-up (+44%) exhibited more FI fluctuations.

CONCLUSIONS

Short-term FI fluctuations were neither small nor random. Instead, as older adults become frailer, their measured health also becomes more unstable; hence, short-term fluctuations in overall health status can be seen as a concomitant phenomenon of the aging process. Researchers and clinicians should be aware of the existence of reversible fluctuations in the FI over weeks and months and its consequences for frailty monitoring.

Addressing gaps in pain research from an integrated whole person perspective

ABSTRACT

While our understanding of pain is rapidly growing, some areas of pain research are lagging behind. This article discusses two current and inter-related gaps in knowledge that are in need of addressing: first, the connections between "brain" and "body" components of pain; and second, the process of endogenous pain resolution. Historical reasons for these research gaps are discussed and solutions are outlined based on an integrative, whole person research approach. These include comprehensive mapping of the mechanosensory and nociceptive innervation of deep tissues; developing objective, non-invasive measurements to quantify the metabolic, structural and mechanical components of the peripheral tissue environment; integrating our understanding of pain pathophysiology, across whole organs and whole body, as well as across bio-psycho-social domains; and understanding the interplay of nervous system and peripheral tissue mechanisms that promote the endogenous resolution of pain and prevent its acute-to-chronic transition. Current NIH-led efforts in these areas are outlined, including several studies within the NIH HEAL (or Help End Addition Long Term) initiative and the National Center for Complementary and Integrative Health's strategic priorities in whole person research.

Emotion Dynamics among Late Adolescents and Emerging Adults: The Role of Maternal Privacy Invasion Perceptions

Prior research suggests that youth experience immediate emotional distress following privacy invasion, but it is unclear whether and how persistent privacy invasion over longer periods destabilizes the intrapersonal emotional regulatory functions that privacy serves. This study investigated whether late adolescents and emerging adults who reported different patterns of maternal privacy invasion over a full academic year showed differences in emotion regulation, as reflected by the frequency and lability of negative and positive emotional experiences. Participants were first-year university students (n = 349; 60.2% female) in Hong Kong, aged 17 to 24 (MT1 = 18.20, SDT1 = 1.10). They self-reported maternal privacy invasion perceptions and negative and positive emotions 16 times, at bi-weekly intervals. Latent class growth analyses divided participants into a Higher Invasion Perceptions group (24.9%), a Moderate Invasion Perceptions group (46.4%), and a Lower Invasion Perceptions group (28.7%). A one-way MANCOVA examined potential differences in negative and positive emotion dynamics across groups, indexed by frequency (means) and instability (mean square of successive differences and probability of acute change). In line with predictions, both the Higher Invasion and Moderate Invasion groups reported higher negative emotion frequency and instability, compared to the Lower Invasion group. However, groups showed no significant differences regarding positive emotion frequency and instability. The findings indicate that perceptions of maternal privacy invasion predict youth's negative emotion regulation processes over their first collegiate year. Prolonged, higher levels of maternal privacy invasion may disrupt the intrapersonal regulatory functions that privacy serves over time.

Within-person fluctuations of fatigue in patients with a clinical diagnosis of systemic sclerosis and its relationship with mood, pain, sleep and physical activity

Objectives

To explore the within-person fluctuations of fatigue in systemic sclerosis and its association with negative affect, positive affect, pain, perceived exertion of physical activity and quality of sleep.

Methods

We performed an ecological momentary assessment study in adult patients with a clinical diagnosis of systemic sclerosis. During 14 days, patients completed daily assessments of fatigue severity, negative affect, positive affect, pain, quality of sleep and perceived exertion of physical activity at four fixed time points. The day-to-day fluctuations in fatigue were quantified by the intra-individual variance and probability of acute change, capturing the magnitude and frequency of clinical relevant within-person day-to-day fluctuations, respectively. Using multilevel models, the within-person association between fatigue and the daily assessments were analysed.

Results

Fifty-seven patients with systemic sclerosis participated. The mean (standard deviation) intra-individual variance was 1.08 (0.42) and the probability of acute change was mean (standard deviation) 0.40 (0.14), ranging from 0.08 to 0.77. For fatigue, a within-person variation of 51% was observed. Multilevel analyses showed that higher average levels and daily increases in negative affect, pain and perceived exertion of physical activity were associated with more fatigue, while the opposite was observed for positive affect and quality of sleep. Positive affect demonstrated the strongest association with fatigue fluctuations.

Conclusion

This is the first quantitative study showing that fatigue in systemic sclerosis is characterized by a dynamic course and that approximately half of the day-to-day fluctuations within persons are clinically meaningful. Furthermore, our results indicate that integrating activities with positive impact on mood into fatigue treatment strategies might reduce the frequency of fatigue fluctuations.

Intraindividual variability in post-stroke cognition and its relationship with activities of daily living and social functioning: an ecological momentary assessment approach

INTRODUCTION

Ecological momentary assessment (EMA) is a methodological approach to studying intraindividual variation over time. This study aimed to use EMA to determine the variability of cognition in individuals with chronic stroke, identify the latent classes of cognitive variability, and examine any differences in daily activities, social functioning, and neuropsychological performance between these latent classes.

METHODS

Participants (N = 202) with mild-to-moderate stroke and over 3-month post-stroke completed a study protocol, including smartphone-based EMA and two lab visits. Participants responded to five EMA surveys daily for 14 days to assess cognition. They completed patient-reported measures and neuropsychological assessments during lab visits. Using latent class analysis, we derived four indicators to quantify cognitive variability and identified latent classes among participants. We used ANOVA and Chi-square to test differences between these latent classes in daily activities, social functioning, and neuropsychological performance.

RESULTS

The latent class analysis converged on a three-class model. The moderate and high variability classes demonstrated significantly greater problems in daily activities and social functioning than the low class. They had significantly higher proportions of participants with problems in daily activities and social functioning than the low class. Neuropsychological performance was not statistically different between the three classes, although a trend approaching statistically significant difference was observed in working memory and executive function domains.

DISCUSSION

EMA could capture intraindividual cognitive variability in stroke survivors. It offers a new approach to understanding the impact and mechanism of post-stroke cognitive problems in daily life and identifying individuals benefiting from self-regulation interventions.

The Contribution of Sleep Quality and Psychological Factors to the Experience of Within-Day Pain Fluctuations Among Individuals With Temporomandibular Disorders

We assessed the impact of day-to-day sleep quality and psychological variables (catastrophizing, negative affect, and positive affect) to within-day pain fluctuations in 42 females with painful temporomandibular disorders (TMD) using electronic diaries. More specifically, we examined the contribution of these variables to the likelihood of experiencing pain exacerbations defined as 1) an increase of 20 points (or more) in pain intensity on a 0 to 100 visual analog scale from morning to evening, and/or 2) a transition from mild-to-moderate pain over the course of the day; and pain decreases defined as 3) a decrease of 20 points (or more) in pain intensity (visual analog scale) from morning to evening, and/or 4) a reduction from moderate-to-mild pain over the day. The results indicated significantly main effects of sleep on both pain exacerbation outcomes (both P's < .05), indicating that nights with better sleep quality were less likely to be followed by clinically meaningful pain exacerbations on the next day. The results also indicated that days characterized by higher levels of catastrophizing were associated with a greater likelihood of pain exacerbations on the same day (both P's < .05). Daily catastrophizing was the only variable significantly associated with within-day pain decrease indices (both P's < .05). None of the other variables were associated with these outcomes (all P's > .05). These results underscore the importance of addressing patients' sleep quality and psychological states in the management of painful TMD. PERSPECTIVE: These findings highlight the significance of sleep quality and pain catastrophizing in the experience of within-day pain fluctuations among individuals with TMD. Addressing these components through tailored interventions may help to alleviate the impact of pain fluctuations and enhance the overall well-being of TMD patients.

Parent Anxiety, Depression, Protective Responses, and Parenting Stress in the Context of Parent and Child Chronic Pain: A Daily Diary Study of Parent Variability

Parents with (vs without) chronic pain report poorer psychosocial functioning (eg, worse mental health, parenting difficulties), which has been linked to poorer child outcomes (eg, child pain). However, emerging research suggests that individuals vary in their functioning from day-to-day, particularly those with chronic pain. This study used daily diaries to compare parents with (versus without) chronic pain on variability in their anxiety, mood, protective responses, and parenting stress. We also examined parent chronic pain status as a moderator of the associations between parent variability and youth daily pain and interference. Participants were 76 youth with chronic pain (Mage = 14.26; 71.1% female) and one of their parents (89.5% mothers; n = 38 or 50.0% endorsing chronic pain). Parents and youth completed self-report questionnaires and 7 days of diaries. Parent variability was calculated to reflect the frequency and size of day-to-day changes. Multilevel models revealed that parents with (vs without) chronic pain were significantly more variable in their parenting stress, but not in their anxiety, mood, or protective responses. Contrary to hypotheses, parent variability was not significantly related to youth daily pain intensity or interference and parent chronic pain did not moderate any associations. Instead, mean levels of parent anxiety, protective responses, and parenting stress across the week significantly predicted youth daily pain interference. Findings suggest that while variability was observed among parents (with and without chronic pain) of youth with chronic pain, it did not significantly predict youth's daily pain-related functioning. Further research is needed to confirm these initial findings. PERSPECTIVE: Parents with chronic pain have expressed concerns that the variable nature of their pain negatively impacts their children. Our results found that parents (with and without chronic pain) were variable in their anxiety, mood, protective responses, and parenting stress, but this variability did not significantly predict youth's chronic pain-related functioning.

Increased Pain Variability in Patients With Chronic Pain: A Role for Pain Catastrophizing

Pain is an inherently negative perceptual and affective experience that acts as a warning system to protect the body from injury and illness. Pain unfolds over time and is influenced by myriad factors, making it highly dynamic. Despite this, statistical measures often treat any intraindividual variability in pain ratings as noise or error. This is consequential, especially for research on chronic pain, because pain variability is associated with greater pain severity and depression. Yet, differences in pain variability between patients with chronic pain and controls in response to acute pain has not been fully examined-and it is unknown if dispositional factors such as pain catastrophizing (negative cognitive-affective response to potential or actual pain in which attention cannot be diverted away from pain) relate to pain variability. In the current study, we recruited chronic-pain patients (N = 30) and pain-free controls (N = 22) to complete a 30-second thermal pain task where they continually rated a painful thermal stimulus. To quantify pain variability and capture potential dynamics, we used both a traditional intraindividual standard deviation (iSD) metric of variability and a novel derivatives approach. For both metrics, patients with chronic pain had higher variability in their pain ratings over time, and pain catastrophizing significantly mediated this relationship. This suggests patients with chronic pain experience pain stimuli differently over time, and pain catastrophizing may account for this differential experience. PERSPECTIVE: The present study demonstrates (using multiple variability metrics) that chronic pain patients show more variability when rating experimental pain stimuli, and that pain catastrophizing helps explain this differential experience. These results provide preliminary evidence that short-term pain variability could have utility as a clinical marker in pain assessment and treatment.

Sleep Disruption Moderates the Daily Dynamics of Affect and Pain in Sickle Cell Disease

Persons with sickle cell disease (SCD) often experience pain that can interfere with quality of life and daily activities. Pain can modulated by affect and sleep continuity; however, few studies have explored how these factors complementarily influence pain in adults with SCD. The study aims were to investigate 1) whether pain levels were heightened on days characterized by low positive affect and high negative affect, and 2) whether the relationship between affect and pain was intensified following nights of disrupted sleep. Adults with SCD (N = 25) completed ecological momentary assessments and daily sleep diaries. Mixed models were used to analyze the main and interactive effects of daily affect (positive affect and negative affect) and sleep disruption (wake after sleep onset and frequency of awakenings) on both daily average pain and daily maximum pain. Results suggested that daily average pain and maximum pain tended to be higher on days of low positive affect and high negative affect. Furthermore, the frequency of nocturnal awakenings moderated the relationship between positive affect and pain. On days where there were higher frequencies of nocturnal awakenings, low positive affect was associated with both average and maximum pain; however, this association was not observed with lower frequencies of nocturnal awakenings. The association between negative affect and maximum pain was also stronger at higher levels of awakenings. Results highlight the relevance of adjunctive interventions that target affect among populations with SCD and further suggest that sleep continuity may further facilitate these interventions, highlighting the importance of multimodal treatments. PERSPECTIVE: This study examined the effects of affect and sleep on pain among adults with sickle cell disease (SCD). Higher pain occurred on days of low positive affect and high negative affect, particularly following nights of more frequent awakenings. These findings emphasize the importance of addressing affect and sleep in SCD treatment.

The association of pain impact and sleep disruption with opioid withdrawal during opioid-use disorder treatment

AIMS

Persons with opioid-use disorder (OUD) often experience opioid withdrawal and opioid craving, which can drive continued opioid use and treatment discontinuation. In addition, hyperalgesia is common among persons with OUD, yet few studies have examined the role of pain impact during OUD treatment. The purpose of the present study was to test whether opioid withdrawal and craving were elevated in the context of greater pain impact (i.e. greater pain intensity and interference), and whether these associations changed throughout treatment.

METHODS

Participants in residential OUD treatment (n = 24) wore wrist actigraphy to measure sleep and completed daily measures of pain impact, opioid withdrawal and opioid craving for up to 28 days. Mixed effects models were used to examine whether daily elevations in pain impact and sleep continuity were associated with withdrawal severity and opioid craving.

RESULTS

Elevations in withdrawal, but not craving, occurred on days when individuals reported higher scores on the pain impact scale. Associations between pain impact and withdrawal were present throughout treatment, but stronger during early treatment. In contrast, both withdrawal and opioid craving were elevated following nights of greater wake after sleep onset and awakenings, but these findings were often more pronounced in early treatment.

CONCLUSIONS

Pain impact and sleep disturbance are 2 factors associated with opioid withdrawal and opioid craving. Novel pharmacotherapies and scalable adjunctive interventions targeting sleep and pain impact should be tested in future work to improve OUD treatment outcomes.

Classifying Self-Reported Rheumatoid Arthritis Flares Using Daily Patient-Generated Data From a Smartphone App: Exploratory Analysis Applying Machine Learning Approaches

BACKGROUND

The ability to predict rheumatoid arthritis (RA) flares between clinic visits based on real-time, longitudinal patient-generated data could potentially allow for timely interventions to avoid disease worsening.

OBJECTIVE

This exploratory study aims to investigate the feasibility of using machine learning methods to classify self-reported RA flares based on a small data set of daily symptom data collected on a smartphone app.

METHODS

Daily symptoms and weekly flares reported on the Remote Monitoring of Rheumatoid Arthritis (REMORA) smartphone app from 20 patients with RA over 3 months were used. Predictors were several summary features of the daily symptom scores (eg, pain and fatigue) collected in the week leading up to the flare question. We fitted 3 binary classifiers: logistic regression with and without elastic net regularization, a random forest, and naive Bayes. Performance was evaluated according to the area under the curve (AUC) of the receiver operating characteristic curve. For the best-performing model, we considered sensitivity and specificity for different thresholds in order to illustrate different ways in which the predictive model could behave in a clinical setting.

RESULTS

The data comprised an average of 60.6 daily reports and 10.5 weekly reports per participant. Participants reported a median of 2 (IQR 0.75-4.25) flares each over a median follow-up time of 81 (IQR 79-82) days. AUCs were broadly similar between models, but logistic regression with elastic net regularization had the highest AUC of 0.82. At a cutoff requiring specificity to be 0.80, the corresponding sensitivity to detect flares was 0.60 for this model. The positive predictive value (PPV) in this population was 53%, and the negative predictive value (NPV) was 85%. Given the prevalence of flares, the best PPV achieved meant only around 2 of every 3 positive predictions were correct (PPV 0.65). By prioritizing a higher NPV, the model correctly predicted over 9 in every 10 non-flare weeks, but the accuracy of predicted flares fell to only 1 in 2 being correct (NPV and PPV of 0.92 and 0.51, respectively).

CONCLUSIONS

Predicting self-reported flares based on daily symptom scorings in the preceding week using machine learning methods was feasible. The observed predictive accuracy might improve as we obtain more data, and these exploratory results need to be validated in an external cohort. In the future, analysis of frequently collected patient-generated data may allow us to predict flares before they unfold, opening opportunities for just-in-time adaptative interventions. Depending on the nature and implication of an intervention, different cutoff values for an intervention decision need to be considered, as well as the level of predictive certainty required.

Harm Reduction for Opioid Use Disorder: Strategies and Outcome Metrics

Tweet: The authors discuss harm reduction strategies and associated outcome metrics in relation to the ongoing opioid crisis.

The Effect of Everyday-Life Social Contact on Pain

Pain is a biopsychosocial phenomenon, resulting from the interplay between physiological and psychological processes and social factors. Given that humans constantly interact with others, the effect of social factors is particularly relevant. Documenting the significance of the social modulation of pain, an increasing number of studies have investigated the effect of social contact on subjective pain intensity and pain-related physiological changes. While evidence suggests that social contact can alleviate pain, contradictory findings indicate an increase in pain intensity and a deterioration of pain coping strategies. This evidence primarily stems from studies examining the effect of social contact on pain within highly controlled laboratory conditions. Moreover, pain assessments often rely on one-time subjective reports of average pain intensity across a predefined period. Ecological momentary assessments (EMAs) can circumvent these problems, as they can capture diverse aspects of behavior and experiences multiple times a day, in real time, with high resolution, and within naturalistic and ecologically valid settings. These multiple measures allow for the examination of fluctuations of pain symptoms throughout the day in relation to affective, cognitive, behavioral, and social factors. In this opinion paper, we review the current state and future relevance of EMA-based social pain research in daily life. Specifically, we examine whether everyday-life social support reduces or enhances pain. The first part of the paper provides a comprehensive overview of the use of EMA in pain research and summarizes the main findings. The review of the relatively limited number of existing EMA studies shows that the association between pain and social contact in everyday life depends on numerous factors, including pain syndromes, temporal dynamics, the nature of social interactions, and characteristics of the interaction partners. In line with laboratory research, there is evidence that everyday-life social contact can alleviate, but also intensify pain, depending on the type of social support. Everyday-life emotional support seems to reduce pain, while extensive solicitous support was found to have opposite effects. Moreover, positive short-term effects of social support can be overshadowed by other symptoms such as fatigue. Overall, gathering and integrating experiences from a patient's social environment can offer valuable insights. These insights can help interpret dynamics in pain intensity and accompanying symptoms such as depression or fatigue. We conclude that factors determining the reducing versus enhancing effects of social contact on pain need to be investigated more thoroughly. We advocate EMA as the assessment method of the future and highlight open questions that should be addressed in future EMA studies on pain and the potential of ecological momentary interventions for pain treatment.

Nocebo hyperalgesia and other expectancy-related factors in daily fibromyalgia pain: Combining experimental and electronic diary methods

OBJECTIVE

Expectancies are known to shape pain experiences, but it remains unclear how different types of expectancies contribute to daily pain fluctuations in fibromyalgia. This combined experimental and diary study aims to provide insights into how experimentally-derived nocebo hyperalgesia and other, diary-derived, expectancy-related factors are associated with each other and with daily pain in fibromyalgia.

METHODS

Forty-one female patients with fibromyalgia first participated in a lab procedure measuring nocebo hyperalgesia magnitude, then filled out an electronic diary 3 times a day over 3 weeks regarding the expectancy-related factors of pain expectancy, anxiety, optimism, and pain-catastrophizing thoughts, and current pain intensity.

RESULTS

Our results indicate that experimentally-induced nocebo hyperalgesia was not significantly related to diary-assessed expectancy-related factors and did not predict daily fibromyalgia pain. Higher levels of the self-reported expectancy-related factors pain expectancy and pain catastrophizing, but not anxiety and optimism, predicted moment-to-moment pain increases in fibromyalgia, after controlling for current pain, moment-of-day and all other expectancy-related factors.

CONCLUSION

Our exploratory research findings indicate that self-reported expectancy-related factors, particularly pain expectancy and pain catastrophizing, are potentially more relevant for predicting daily pain experience than experimentally-induced nocebo hyperalgesia. Further translation of nocebo hyperalgesia is needed from experimental to Ecological Momentary Assessment research. Our findings imply that targeting the decrease in pain expectancy and catastrophizing thoughts e.g., via Cognitive Behavioral Therapy, have potential for improving daily pain levels in fibromyalgia.

SOMAScience: A Novel Platform for Multidimensional, Longitudinal Pain Assessment

Chronic pain is one of the most significant health issues in the United States, affecting more than 20% of the population. Despite its contribution to the increasing health crisis, reliable predictors of disease development, progression, or treatment outcomes are lacking. Self-report remains the most effective way to assess pain, but measures are often acquired in sparse settings over short time windows, limiting their predictive ability. In this paper, we present a new mobile health platform called SOMAScience. SOMAScience serves as an easy-to-use research tool for scientists and clinicians, enabling the collection of large-scale pain datasets in single- and multicenter studies by facilitating the acquisition, transfer, and analysis of longitudinal, multidimensional, self-report pain data. Data acquisition for SOMAScience is done through a user-friendly smartphone app, SOMA, that uses experience sampling methodology to capture momentary and daily assessments of pain intensity, unpleasantness, interference, location, mood, activities, and predictions about the next day that provide personal insights into daily pain dynamics. The visualization of data and its trends over time is meant to empower individual users' self-management of their pain. This paper outlines the scientific, clinical, technological, and user considerations involved in the development of SOMAScience and how it can be used in clinical studies or for pain self-management purposes. Our goal is for SOMAScience to provide a much-needed platform for individual users to gain insight into the multidimensional features of their pain while lowering the barrier for researchers and clinicians to obtain the type of pain data that will ultimately lead to improved prevention, diagnosis, and treatment of chronic pain.

Daily Pain Experiences in Chronic Pancreatitis: Identifying Pain Phenotypes

OBJECTIVES

Pain, the hallmark symptom of chronic pancreatitis (CP), remains difficult to assess. To capture the variability of pain that patients can experience day to day, this study used pain diaries to describe daily pain experiences and identify pain phenotypes.

METHODS

This study is a secondary data analysis from a pilot trial examining cognitive behavioral therapy for pain treatment in CP. Before treatment, patients completed an online daily pain diary using the Brief Pain Inventory for 7 days. Using indicators of pain magnitude, pain variability, pain synchrony along with least, worst, and average pain intensity levels, we identified pain patterns using K-means clustering.

RESULTS

Of 30 patients in the pilot trial, a total of 27 patients (mean age of 49.8 years, 80% women) had complete data to include in this report. Four clusters were identified: cluster 1, lowest pain magnitude (n = 3); cluster 2, moderate pain magnitude and high pain variability (n = 4); cluster 3, moderate pain magnitude and low pain variability (n = 9); and cluster 4, highest pain magnitude and lowest pain variability (n = 11).

CONCLUSIONS

Daily pain diaries offer a novel way of evaluating the dynamic pain experiences in CP. Although 4 distinct pain patterns were identified, further studies are needed to validate these findings.

Mapping the associations of daily pain, sleep, and psychological distress in a U.S. sample

Chronic pain, sleep problems, and psychological distress (PD) can be disabling conditions and previous research has shown that they are associated. The nuances of the comorbid nature of these conditions may be important to understand for those who treat these conditions. This study examined the bidirectional associations of these health factors concurrently and over time in a sample of U.S. adults (N = 1,008, Mage = 57.68) from the Midlife in the United States (MIDUS) study. Participants reported on their daily pain, sleep quantity, and psychological distress over eight days. A modified Random Intercept Cross-lagged Panel Model was used to analyze the relations, starting with the whole sample and then a comparison of those with and without chronic pain. Results indicated that nightly variation in sleep quantity predicted next day psychological distress for both groups. Sleep quantity also predicted next-day pain, but only for individuals with chronic pain. Associations between pain and psychological distress were found both at the daily level and individual (between-person) level. This between-person association was stronger for those with chronic pain. The lagged associations between sleep, and both pain and psychological distress for the chronic pain group indicate that, increased quantity of sleep predicts decreased next-day pain and psychological distress. Providers could consider this unidirectional lagged relationship when prioritizing treatment for patients with these comorbid conditions. Future research may examine whether responsive, just-in-time treatments might intervene after participants wake from a poor night's sleep to counteract the negative effects of reduced sleep on PD and pain.

Heart rate variability is not suitable as a surrogate marker for pain intensity in patients with chronic pain

ABSTRACT

The search towards more objective outcome measurements and consequently surrogate markers for pain started decades ago; however, no generally accepted biomarker for pain has qualified yet. The goal is to explore the value of heart rate variability (HRV) as surrogate marker for pain intensity chronic pain setting. Pain intensity scores and HRV were collected in 366 patients with chronic pain, through a cross-sectional multicenter study. Pain intensity was measured with both the visual analogue scale and numeric rating scale, whereas 16 statistical HRV parameters were derived. Canonical correlation analysis was performed to evaluate the correlation between the dependent pain variables and the HRV parameters. Surrogacy was determined for each HRV parameter with point estimates between 0 and 1 whereby values close to 1 indicate a strong association between the surrogate and the true endpoint at the patient level. Weak correlations were revealed between HRV parameters and pain intensity scores. The highest surrogacy point estimate was found for mean heart rate as marker for average pain intensity on the numeric rating scale with point estimates of 0.0961 (95% confidence interval [CI] 0.0384-0.1537) and 0.0209 (95% CI 0-0.05) for patients without medication use and with medication, respectively. This study indicated that HRV parameters as separate entities are no suitable surrogacy candidates for pain intensity, in a population of chronic pain patients. Further potential surrogate candidates and clinical robust true endpoints should be explored, to find a surrogate measure for the highly individual pain experience.

Feasibility, Acceptability, and Preliminary Efficacy of a Positive Affect Skills Intervention for Adults With Fibromyalgia

Background and Objectives

To examine the feasibility, acceptability, and preliminary efficacy of a positive affect skills intervention for middle-aged and older adults with fibromyalgia syndrome (FMS).

Research Design and Methods

Ninety-five participants with FMS aged 50 and older (94% female) were randomized to 1 of 2 conditions: (a) Lessons in Affect Regulation to Keep Stress and Pain UndeR control (LARKSPUR; n = 49) or (b) emotion reporting/control (n = 46). LARKSPUR included 5 weeks of skill training that targeted 8 skills to help foster positive affect, including (a) noticing positive events, (b) savoring positive events, (c) identifying personal strengths, (d) behavioral activation to set and work toward attainable goals, (e) mindfulness, (f) positive reappraisal, (g) gratitude, and (h) acts of kindness. Outcome data were collected via online surveys at baseline, postintervention, and 1-month follow-up.

Results

Completion rates (88%) and satisfaction ratings (10-point scale) were high (LARKSPUR: M = 9.14, standard deviation (SD) = 1.49; control: M = 8.59, SD = 1.97). Improvements were greater in LARKSPUR participants compared with control participants on measures of positive affect (Cohen's d = 0.19 [0.15, 0.24]), negative affect (Cohen's d = -0.07 [-0.11, -0.02]), and pain catastrophizing (Cohen's d = -0.14 [-0.23, -0.05]). Improvements in positive affect (Cohen's d = 0.17 [0.13, 0.22]) and negative affect (Cohen's d = -0.11 [-0.15, -0.06]) were maintained at 1-month follow-up. Dose-response analyses indicated that intervention engagement significantly predicted pre-to-post and post-to-follow-up reductions in pain catastrophizing.

Discussion and Implications

The current preliminary findings add to existing literature and highlight the specific potential of internet-delivered positive affect skills programs for adults with FMS.

Clinical Trial Registration

NCT04869345.

Day-to-day fluctuations of fatigue severity in individuals with knee osteoarthritis: an ecological momentary assessment approach

Objective

The variable course of fatigue adds to the disease burden of patients with OA yet it has been poorly understood. This study aimed to describe within-person fluctuations of fatigue severity and explore its associations with pain, positive affect, negative affect, sleep, and perceived exertion of physical activity.

Methods

Individuals with chronic knee pain or a clinical diagnosis of knee OA ≥40 years of age completed daily assessments about fatigue, pain, positive affect, negative affect, sleep, perceived exertion of physical activity (numeric rating scale 0-10), and overwhelming fatigue (yes/no) on a smartphone over 14 days. Within-person fluctuations of fatigue severity were described by the probability of acute changes (PACs) and s.d.s. Associations with pain, positive affect, negative affect, sleep, and perceived exertion of physical activity were explored using multilevel models.

Results

Forty-nine individuals were included (mean age 63.4 years; 82% female). PACs and s.d.s of within-person daily fatigue fluctuations ranged from 0.00 to 0.80 and 0.35 to 2.95, respectively. Within-person associations of fatigue severity were moderate for positive affect [β = -0.57 (95% CI -0.67, -0.47)], weak for pain [β = 0.41 (95% CI 0.29, 0.53)] and negative affect [β = 0.40 (95% CI 0.21, 0.58)], and negligible for sleep [β = -0.13 (95% CI -0.18, -0.08)] and perceived exertion of physical activity [β = 0.18 (95% CI 0.09, 0.26)].

Conclusion

Some individuals showed almost stable day-to-day levels of fatigue severity, whereas others experienced a substantial number of clinically relevant fluctuations. To reduce the burden of daily fatigue fluctuations, our results suggest that pain, positive and negative affect rather than sleep and perceived exertion of physical activity should be considered as potential targets.

A systematic review of neurophysiological sensing for the assessment of acute pain

Pain is a complex and personal experience that presents diverse measurement challenges. Different sensing technologies can be used as a surrogate measure of pain to overcome these challenges. The objective of this review is to summarise and synthesise the published literature to: (a) identify relevant non-invasive physiological sensing technologies that can be used for the assessment of human pain, (b) describe the analytical tools used in artificial intelligence (AI) to decode pain data collected from sensing technologies, and (c) describe the main implications in the application of these technologies. A literature search was conducted in July 2022 to query PubMed, Web of Sciences, and Scopus. Papers published between January 2013 and July 2022 are considered. Forty-eight studies are included in this literature review. Two main sensing technologies (neurological and physiological) are identified in the literature. The sensing technologies and their modality (unimodal or multimodal) are presented. The literature provided numerous examples of how different analytical tools in AI have been applied to decode pain. This review identifies different non-invasive sensing technologies, their analytical tools, and the implications for their use. There are significant opportunities to leverage multimodal sensing and deep learning to improve accuracy of pain monitoring systems. This review also identifies the need for analyses and datasets that explore the inclusion of neural and physiological information together. Finally, challenges and opportunities for designing better systems for pain assessment are also presented.

Intraindividual pain variability metrics for youth with sickle cell disease: Relations to health outcomes

BACKGROUND

While the majority of pediatric sickle cell disease (SCD) research has used mean pain intensity as the only pain metric, recent evidence suggests this metric alone is inadequate in describing the intraindividual variability in SCD pain experiences and subsequent impact. There is limited information on other intraindividual pain metrics in youth with SCD, or how they relate to health outcomes in this population. The aims of this study were to describe differing patterns of intraindividual pain metrics derived from ecological momentary assessments (EMAs) of youth with SCD and to characterize the unique relationships between these metrics and health outcomes.

METHODS

Eighty-eight youth with SCD, aged 8-17 (mean age = 11.6), were recruited from three regional pediatric SCD clinics in the United States. At baseline, youth and their guardians reported on demographic and disease information. Then youth completed twice daily EMAs for up to 4 weeks. Pain metrics derived from EMA data were calculated including mean daily pain intensity (DP), SD-DP (standard deviation of DP), proportion of pain days (PPD), and 90th percentile of DP (p90). Pearson correlations were calculated between pain metrics and health outcomes.

RESULTS

High DP and SD-DP were correlated with more anxiety symptoms, while high SD-DP and p90 were correlated with more depression symptoms. High SD-DP was correlated with low self-esteem, and high DP and PPD were correlated with low sickle cell self-efficacy. For healthcare utilization due to pain, high p90 was correlated with more emergency department visits, while high DP, p90, and PPD were correlated with more healthcare contacts.

CONCLUSION

There are distinct associations between pain variability metrics beyond DP and health outcomes. Collectively, the patterns of associations suggest the utility of these pain metrics for determining risk in relation to specific health outcomes for youth with SCD.

Task-based measures of sensitivity to physical activity predict daily life pain and mood among people living with back pain

BACKGROUND

Clinical interventions aim to improve the daily life experiences of patients. However, past research has highlighted important discrepancies between commonly used assessments (e.g. retrospective questionnaires) and patients' daily life experiences of pain. These gaps may contribute to flawed clinical decision-making and ineffective care. Recent work suggests that real-time, task-based clinical assessments may help reduce these discrepancies by adding predictive value in explaining daily life pain experiences. This study aimed to investigate these relationships by evaluating whether task-based measures of sensitivity to physical activity (SPA) predict daily life pain and mood, beyond traditional pain-related questionnaires.

METHODS

Adults with back pain (<6-month onset) answered pain-related questionnaires and completed a standardized lifting task. SPA-Pain, SPA-Sensory and SPA-Mood were, respectively, assessed as task-evoked changes in pain intensity, pressure pain threshold (back, hands), situational catastrophizing. Over the next 9 days, daily life pain and mood were assessed using smartphone-based ecological momentary assessment (EMA-Pain and EMA-Mood, respectively) with stratified random sampling. Data analyses estimated fixed effects (b) using multilevel linear modelling with random intercepts.

RESULTS

Median EMA completion per participant was 66.67% (n = 67 participants). After controlling for covariates, SPA-Pain was associated with EMA-Pain (b = 0.235, p = 0.002) and SPA-Psych approached significance with EMA-Mood (b = -0.159, p = 0.052).

CONCLUSIONS

Task-based assessment of SPA helps explain daily life pain and mood among adults with back pain, beyond traditional questionnaires. Adding task-based assessment of SPA may achieve a more complete picture of pain and mood in daily life, offering clinicians better guidance when prescribing activity-based interventions that are designed to modify daily life behaviour, such as graded activity.

SIGNIFICANCE

This study found that, among people with back pain, task-based measures of sensitivity to physical activity contribute additional predictive value for daily life pain and mood beyond self-report questionnaires. Findings suggest that real-time, task-based measures may help mitigate some of the shortcomings that are commonly associated with retrospective questionnaires.

The Effects of Recovery Sleep on Experimental Pain

Recent research suggests that recovery sleep (RS) has the potential to restore pain sensitivity and modulation after hyperalgesia due to preceding sleep deprivation. However, it has not yet been systematically examined whether the restoration of these pain parameters is driven by sleep characteristics of RS. Thus, the present study assessed changes in experimental pain during RS after total sleep deprivation (TSD) to test whether RS parameters predicted the restoration of the pain system. Thirty healthy participants completed one night of habitual sleep, one night of TSD and a subsequent recovery night. At-home sleep during baseline and recovery was assessed using portable polysomnography and a questionnaire. Before and after each night pressure pain thresholds (PPTs), temporal pain summation (TSP) and conditioned pain modulation (CPM) were assessed. PPTs decreased after TSD and increased following RS, indicating a restoration of pain sensitivity after hyperalgesia. RS characteristics did not predict this restoration, suggesting other mechanisms (eg, changes in serotonergic activity) underlying the observed pain changes. TSP indicated a lack of effect of experimental sleep manipulations on excitatory processes whereas CPM lacked sufficient reliability to investigate inhibitory processes. Thus, results indicate moderate effects of sleep manipulations on pain sensitivity, but not on pain modulation. PERSPECTIVE: This article highlights the potential of recovery sleep to let pain thresholds return to normal following their decrease after a night of total sleep deprivation. In contrast, endogenous pain modulation (temporal pain summation, conditioned pain modulation) was not affected by sleep deprivation and recovery sleep.

Cannabis use and sleep quality in daily life: An electronic daily diary study of adults starting cannabis for health concerns

BACKGROUND

Real world patterns of cannabis use for health concerns are highly variable and rarely overseen by a physician. Pragmatic effectiveness studies with electronic daily diaries that capture person-specific patterns of cannabis use and health symptoms may help clarify risks and benefits.

METHODS

As part of a larger, randomized trial (NCT03224468), adults (N = 181) seeking cannabis for insomnia, pain, or anxiety or depressive symptoms were randomized to obtain a medical cannabis card immediately (MCC) or a waitlist control (WLC) and completed 12-weeks of daily web-based surveys on cannabis use and sleep, pain, and depressive symptoms.

RESULTS

Completion rates of daily surveys were moderate to high (median completed: 72 out of 90 days). Daily reports of cannabis use were consistent with monthly interview assessments and urinalysis. The MCC group increased cannabis use frequency in the 12 weeks following randomization, while WLC did not. Among the MCC group, self-reported sleep quality was significantly higher on cannabis use days, compared to nonuse days. The MCC group displayed long-term sleep improvements, consistent with increasing cannabis frequency. No improvements were found for pain or depressive symptoms.

CONCLUSION

Cannabis use is associated with same day improvements in self-reported sleep quality, but not pain or depressive symptoms, although sleep improvements occurred in the context of increased frequency of cannabis use, raising the risk for cannabis use disorder. Daily web-based assessments of cannabis appear valid and feasible in adults seeking cannabis for health concerns, providing a flexible, complementary method for future real-world effectiveness studies with expanded and objective measures.

Inter-individual variability in mechanical pain sensation in patients with cervicogenic headache: an explorative study

Currently, evidence for effective physiotherapy interventions in patients with cervicogenic headache (CeH) is inconsistent. Although inter-individual variability in pain response is predictive for successful physiotherapy interventions, it was never explored in patients with CeH. Therefore the objective of the current study was to explore inter-individual variability in mechanical pain sensation, and its association with biopsychosocial-lifestyle (BPSL) characteristics in patients with CeH. A cross-sectional explorative analysis of inter-individual variability in mechanical pain sensation in 18 participants with CeH (29-51 years) was conducted. Inter-individual variability in mechanical pain sensation (standard deviations (SDs), F-statistics, Measurement System Analysis) was deducted from bilateral pressure pain thresholds of the suboccipitals, erector spine, tibialis anterior. BPSL-characteristics depression, anxiety, stress (Depression Anxiety Stress Scale-21), quality of life (Headache Impact Test-6), sleep-quality (Pittsburgh Sleep Quality Index), and sedentary time (hours/week) were questioned. Inter-individual variability in mechanical pain sensation explained 69.2% (suboccipital left), 86.8% (suboccipital right), 94.6% (erector spine left), 93.2% (erector spine right), 91.7% (tibialis anterior left), and 82% (tibialis anterior right) of the total variability in patients with CeH. The significant p-values and large F-statistic values indicate inter-individual differences in SDs. Significant associations between (1) lower quality of life and lower SDs of the suboccipital left PPT (p .005), and (2) longer sedentary time and higher SDs of the suboccipital left PPT (p .001) were observed. Results from our explorative study could suggest inter-individual variability in mechanical pain sensation at the left suboccipitals which associates with quality of life and sedentary time. These novel findings should be considered when phenotyping patients and 'individually' match interventions.

A systematic review and meta-analysis of digital application use in clinical research in pain medicine

IMPORTANCE

Pain is a silent global epidemic impacting approximately a third of the population. Pharmacological and surgical interventions are primary modes of treatment. Cognitive/behavioural management approaches and interventional pain management strategies are approaches that have been used to assist with the management of chronic pain. Accurate data collection and reporting treatment outcomes are vital to addressing the challenges faced. In light of this, we conducted a systematic evaluation of the current digital application landscape within chronic pain medicine.

OBJECTIVE

The primary objective was to consider the prevalence of digital application usage for chronic pain management. These digital applications included mobile apps, web apps, and chatbots.

DATA SOURCES

We conducted searches on PubMed and ScienceDirect for studies that were published between 1st January 1990 and 1st January 2021.

STUDY SELECTION

Our review included studies that involved the use of digital applications for chronic pain conditions. There were no restrictions on the country in which the study was conducted. Only studies that were peer-reviewed and published in English were included. Four reviewers had assessed the eligibility of each study against the inclusion/exclusion criteria. Out of the 84 studies that were initially identified, 38 were included in the systematic review.

DATA EXTRACTION AND SYNTHESIS

The AMSTAR guidelines were used to assess data quality. This assessment was carried out by 3 reviewers. The data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

Before data collection began, the primary outcome was to report on the standard mean difference of digital application usage for chronic pain conditions. We also recorded the type of digital application studied (e.g., mobile application, web application) and, where the data was available, the standard mean difference of pain intensity, pain inferences, depression, anxiety, and fatigue.

RESULTS

38 studies were included in the systematic review and 22 studies were included in the meta-analysis. The digital interventions were categorised to web and mobile applications and chatbots, with pooled standard mean difference of 0.22 (95% CI: -0.16, 0.60), 0.30 (95% CI: 0.00, 0.60) and -0.02 (95% CI: -0.47, 0.42) respectively. Pooled standard mean differences for symptomatologies of pain intensity, depression, and anxiety symptoms were 0.25 (95% CI: 0.03, 0.46), 0.30 (95% CI: 0.17, 0.43) and 0.37 (95% CI: 0.05, 0.69), respectively. A sub-group analysis was conducted on pain intensity due to the heterogeneity of the results (I ² = 82.86%; p = 0.02). After stratifying by country, we found that digital applications were more likely to be effective in some countries (e.g., United States, China) than others (e.g., Ireland, Norway).

CONCLUSIONS AND RELEVANCE

The use of digital applications in improving pain-related symptoms shows promise, but further clinical studies would be needed to develop more robust applications.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021228343.

To Calibrate or not to Calibrate? A Methodological Dilemma in Experimental Pain Research

To calibrate or not to calibrate? This question is raised by almost everyone designing an experimental pain study with supra-threshold stimulation. The dilemma is whether to individualize stimulus intensity to the pain threshold / supra-threshold pain level of each participant or whether to provide the noxious stimulus at a fixed intensity so that everyone receives the identical input. Each approach has unique pros and cons which need to be considered to i) accurately design an experiment, ii) enhance statistical inference in the given data and, iii) reduce bias and the influence of confounding factors in the individual study e.g., body composition, differences in energy absorption and previous experience. Individualization requires calibration, a procedure already irritating the nociceptive system but allowing to match the pain level across individuals. It leads to a higher variability of the stimulus intensity, thereby influencing the encoding of "noxiousness" by the central nervous system. Results might be less influenced by statistical phenomena such as ceiling/floor effects and the approach does not seem to rise ethical concerns. On the other hand, applying a fixed (standardized) intensity reduces the problem of intensity encoding leading to a large between-subjects variability in pain responses. Fixed stimulation intensities do not require pre-exposure. It can be proposed that one method is not preferable over another, however the choice depends on the study aim and the desired level of external validity. This paper discusses considerations for choosing the optimal approach for experimental pain studies and provides recommendations for different study designs. PERSPECTIVE: To calibrate pain or not? This dilemma is related to almost every experimental pain research. The decision is a trade-off between statistical power and greater control of stimulus encoding. The article decomposes both approaches and presents the pros and cons of either approach supported by data and simulation experiment.

Temporal stability of self-reported visual back pain trajectories

ABSTRACT

Low back pain (LBP) follows different pain trajectories, and patients seem to recognize their trajectory. This allows self-reported visual pain trajectories (SRVTs) to support patient-provider communication. Pain trajectories appear stable over time for many patients, but the evidence is sparse. Our objectives were to investigate the (1) temporal stability of SRVTs over 1 year concerning pain intensity and course patterns and (2) association of transitions between SRVTs and changes in pain and disability. This study used data from 2 prospective primary care cohorts: the Danish Chiropractic LBP Cohort (n = 1323) and the GLA:D Back cohort (n = 1135). Participants identified one of the 8 SRVTs at baseline and 12-month follow-up, each asking about LBP trajectories the preceding year. Trajectories were described using 2 subscales (intensity and pattern). Temporal stability was quantified by "stability odds ratios" (ORs), depicting the likelihood of staying in the same SRVT after 12 months compared with baseline, and by "preference ORs," depicting the likelihood of choosing a specific alternative SRVT at follow-up. Both ORs compare the observed proportion with the chance level. Finally, we examined associations between transitioning to a different trajectory and changes in clinical outcomes. Approximately 30% stayed in the same SRVT. The stability ORs were all >1. The preference ORs indicated that transitions occurred mainly to similar SRVTs differing in only 1 subscale. Transitions to less or more intense SRVTs were associated with changes in clinical outcomes in the expected direction. Despite distinctly different SRVTs identified, individuals reported relatively stable LBP phenotypes but with potential for change.

Defining the relationship between pain intensity and disease activity in patients with rheumatoid arthritis: a secondary analysis of six studies

Background

Pain is the main concern of patients with rheumatoid arthritis (RA) while reducing disease activity dominates specialist management. Disease activity assessments like the disease activity score for 28 joints with the erythrocyte sedimentation rate (DAS28-ESR) omit pain creating an apparent paradox between patients’ concerns and specialists’ treatment goals. We evaluated the relationship of pain intensity and disease activity in RA with three aims: defining associations between pain intensity and disease activity and its components, evaluating discordance between pain intensity and disease activity, and assessing temporal changes in pain intensity and disease activity.

Methods

We undertook secondary analyses of five trials and one observational study of RA patients followed for 12 months. The patients had early and established active disease or sustained low disease activity or remission. Pain was measured using 100-mm visual analogue scales. Individual patient data was pooled across all studies and by types of patients (early active, established active and established remission). Associations of pain intensity and disease activity were evaluated by correlations (Spearman’s), linear regression methods and Bland-Altman plots. Discordance was assessed by Kappa statistics (for patients grouped into high and low pain intensity and disease activity). Temporal changes were assessed 6 monthly in different patient groups.

Results

A total of 1132 patients were studied: 490 had early active RA, 469 had established active RA and 173 were in remission/low disease activity. Our analyses showed, firstly, that pain intensity is associated with disease activity in general, and particularly with patient global assessments, across all patient groups. Patient global assessments were a reasonable proxy for pain intensity. Secondly, there was some discordance between pain intensity and disease activity across all disease activity levels, reflecting similar discrepancies in patient global assessments. Thirdly, there were strong temporal relationships between changes in disease activity and pain intensity. When mean disease activity fell, mean pain intensity scores also fell; when mean disease activity increased, there were comparable increases in pain intensity.

Conclusions

These findings show pain intensity is an integral part of disease activity, though it is not measured directly in DAS28-ESR. Reducing disease activity is crucial for reducing pain intensity in RA.

Exploring visual pain trajectories in neck pain patients, using clinical course, SMS-based patterns, and patient characteristics: a cohort study

Background

The dynamic nature of neck pain has so far been identified through longitudinal studies with frequent measures, a method which is time-consuming and impractical. Pictures illustrating different courses of pain may be an alternative solution, usable in both clinical work and research, but it is unknown how well they capture the clinical course. The aim of this study was to explore and describe self-reported visual trajectories in terms of details of patients’ prospectively reported clinical course, their SMS-based pattern classification of neck pain, and patient’s characteristics.

Methods

Prospective cohort study including 888 neck pain patients from chiropractic practice, responding to weekly SMS-questions about pain intensity for 1 year from 2015 to 2017. Patients were classified into one of three clinical course patterns using definitions based on previously published descriptors. At 1-year follow-up, patients selected a visual trajectory that best represented their retrospective 1-year course of pain: single episode, episodic, mild ongoing, fluctuating and severe ongoing.

Results

The visual trajectories generally resembled the 1-year clinical course characteristics on group level, but there were large individual variations. Patients selecting Episodic and Mild ongoing visual trajectories were similar on most parameters. The visual trajectories generally resembled more the clinical course of the last quarter.

Discussion

The visual trajectories reflected the descriptors of the clinical course of pain captured by weekly SMS measures on a group level and formed groups of patients that differed on symptoms and characteristics. However, there were large variations in symptoms and characteristics within, as well as overlap between, each visual trajectory. In particular, patients with mild pain seemed predisposed to recall bias. Although the visual trajectories and SMS-based classifications appear related, visual trajectories likely capture more elements of the pain experience than just the course of pain. Therefore, they cannot be seen as a proxy for SMS-tracking of pain over 1 year.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12998-022-00443-3.

Intra-individual variability and stability of affect and craving among individuals receiving medication treatment for opioid use disorder

Affect and craving are dynamic processes that are clinically relevant in opioid use disorder (OUD) treatment, and can be quantified in terms of intra-individual variability and stability. The purpose of the present analysis was to explore associations between opioid use and variability and stability of affect and craving among individuals receiving medication treatment for OUD (MOUD). Adults (N = 224) with OUD in outpatient methadone or buprenorphine treatment completed ecological momentary assessment (EMA) prompts assessing positive affect, negative affect, opioid craving, and opioid use. Dynamic structural equation modeling (DSEM) was used to quantify person-level indices of magnitude and stability of change. Beta regression was used to examine associations between intra-individual variability and stability and proportion of opioid-use days, when controlling for overall intensity of affect and craving. Results suggested that greater magnitude of craving variability was associated with opioid use on a greater proportion of days, particularly among individuals with lower average craving. Low average positive affect was also associated with higher proportion of days of use. Individuals who experience substantial craving variability in the context of lower average craving may be particularly vulnerable to opioid use during treatment. Ongoing assessment of craving may be useful in identifying treatment needs. Examining correlates of intra-individual variability and stability in MOUD treatment remains a relevant direction for future work.

Investigation on how dynamic effective connectivity patterns encode the fluctuating pain intensity in chronic migraine

Chronic migraine is characterised by persistent headaches for >15 days per month; the intensity of the pain is fluctuating over time. Here, we explored the dynamic interplay of connectivity patterns between regions known to be related to pain processing and their relation to the ongoing dynamic pain experience. We recorded EEG from 80 sessions (20 chronic migraine patients in 4 separate sessions of 25 min). The patients were asked to continuously rate the intensity of their endogenous headache. On different time-windows, a dynamic causal model (DCM) of cross spectral responses was inverted to estimate connectivity strengths. For each patient and session, the evolving dynamics of effective connectivity were related to pain intensities and to pain intensity changes by using a Bayesian linear model. Hierarchical Bayesian modelling was further used to examine which connectivity-pain relations are consistent across sessions and across patients.

The results reflect the multi-facetted clinical picture of the disease. Across all sessions, each patient with chronic migraine exhibited a distinct pattern of pain intensity-related cortical connectivity. The diversity of the individual findings are accompanied by inconsistent relations between the connectivity parameters and pain intensity or pain intensity changes at group level. This suggests a rejection of the idea of a common neuronal core problem for chronic migraine.

Anxiety sensitivity and Pain Experience: a prospective investigation among World Trade Center Responders

Chronic pain is a significant public health problem and is exacerbated by stress. The World Trade Center (WTC) Disaster represents a unique stressor, and responders to the WTC disaster are at increased risk for pain and other health complaints. Therefore, there is a significant need to identify vulnerability factors for exacerbated pain experience among this high-risk population. Anxiety sensitivity (AS), defined as fear of anxiety-related sensations, is one such vulnerability factor associated with pain intensity and disability. Yet, no work has tested the predictive effects of AS on pain, limiting conclusions regarding the predictive utility and direction of associations. Therefore, the current study examined the prospective associations of AS, pain intensity, and pain interference among 452 (M_age = 55.22, SD = 8.73, 89.4% male) responders to the WTC disaster completing a 2-week daily diary study. Using multi-level modeling, AS total score was positively associated with both pain intensity and pain interference, and that AS cognitive concerns, but not social or physical concerns, were associated with increased pain. These results highlight the importance of AS as a predictor of pain complaints among WTC responders and provide initial empirical evidence to support AS as a clinical target for treating pain complaints among WTC responders.

Intraindividual pain variability and phenotypes of pain in sickle cell disease: a secondary analysis from the Pain in Sickle Cell Epidemiology Study

ABSTRACT

Mean pain intensity alone is insufficient to describe pain phenotypes in sickle cell disease (SCD). The objective of this study was to determine impact of day-to-day intraindividual pain variability on patient outcomes in SCD. We calculated metrics of pain variability and pain intensity for 139 participants with <10% missing data in the first 28 days of the Pain in Sickle Cell Epidemiology Study. We performed Spearman rank correlations between measures of intraindividual pain variability and outcomes. We then used k-means clustering to identify phenotypes of pain in SCD. We found that pain variability was inversely correlated with health-related quality of life, except in those with daily or near-daily pain. Pain variability was positively correlated with affective coping, catastrophizing, somatic symptom burden, sickle cell stress, health care utilization, and opioid use. We found 3 subgroups or clusters of pain phenotypes in SCD. Cluster 1 included individuals with the lowest mean pain, lowest temporal instability and dependency, lowest proportion of days with pain and opioid use, and highest physical function. Cluster 2 included individuals with the highest mean pain, highest temporal dependency, highest proportion of days with pain and opioid use, and lowest physical function. Cluster 3 included individuals with high levels of mean pain, highest temporal instability, but with lower temporal dependency, proportion of days with pain and opioid use, and physical function compared with cluster 2. We conclude that intraindividual pain variability is associated with patient outcomes and psychological characteristics in SCD and is useful in delineating phenotypes of pain in SCD.

Osteoarthritis Flares

The phenomenon of flares is a common feature in the daily life of people with osteoarthritis (OA). Characterized by episodes of sudden-onset increases in signs and symptoms, their impact can often be distressing and disabling. Despite their potential to have both short-term and long-term consequences for patients across the whole course of the condition, their occurrence and optimal management are not fully understood. This article provides a contemporary perspective on defining OA flares and their potential triggers, and offers suggestions for how health professionals might explore flare patterns with patients in clinical practice and frame timely best-practice treatment approaches.

Sleep Disturbance and Quality of Life in Rheumatoid Arthritis: Prospective mHealth Study

BACKGROUND

Sleep disturbances and poor health-related quality of life (HRQoL) are common in people with rheumatoid arthritis (RA). Sleep disturbances, such as less total sleep time, more waking periods after sleep onset, and higher levels of nonrestorative sleep, may be a driver of HRQoL. However, understanding whether these sleep disturbances reduce HRQoL has, to date, been challenging because of the need to collect complex time-varying data at high resolution. Such data collection is now made possible by the widespread availability and use of mobile health (mHealth) technologies.

OBJECTIVE

This mHealth study aimed to test whether sleep disturbance (both absolute values and variability) causes poor HRQoL.

METHODS

The quality of life, sleep, and RA study was a prospective mHealth study of adults with RA. Participants completed a baseline questionnaire, wore a triaxial accelerometer for 30 days to objectively assess sleep, and provided daily reports via a smartphone app that assessed sleep (Consensus Sleep Diary), pain, fatigue, mood, and other symptoms. Participants completed the World Health Organization Quality of Life-Brief (WHOQoL-BREF) questionnaire every 10 days. Multilevel modeling tested the relationship between sleep variables and the WHOQoL-BREF domains (physical, psychological, environmental, and social).

RESULTS

Of the 268 recruited participants, 254 were included in the analysis. Across all WHOQoL-BREF domains, participants' scores were lower than the population average. Consensus Sleep Diary sleep parameters predicted the WHOQoL-BREF domain scores. For example, for each hour increase in the total time asleep physical domain scores increased by 1.11 points (β=1.11, 95% CI 0.07-2.15) and social domain scores increased by 1.65 points. These associations were not explained by sociodemographic and lifestyle factors, disease activity, medication use, anxiety levels, sleep quality, or clinical sleep disorders. However, these changes were attenuated and no longer significant when pain, fatigue, and mood were included in the model. Increased variability in total time asleep was associated with poorer physical and psychological domain scores, independent of all covariates. There was no association between actigraphy-measured sleep and WHOQoL-BREF.

CONCLUSIONS

Optimizing total sleep time, increasing sleep efficiency, decreasing sleep onset latency, and reducing variability in total sleep time could improve HRQoL in people with RA.

Pain Expectancy and Positive Affect Mediate the day-to-day Association Between Objectively Measured Sleep and Pain Severity Among Women With Temporomandibular Disorder

The majority of individuals with temporomandibular disorders (TMD) experience sleep disturbance, which can maintain and exacerbate chronic pain. However, the factors underlying the sleep-pain link have not been fully elucidated, especially beyond the laboratory. Sleep deprivation can induce threat interpretation bias, as well as impairment in positive affective functioning. Using both actigraphy and daily diaries, we examined whether morning pain expectancy and positive affect mediate the association between previous night's sleep disturbance and next-day overall pain severity. Total sleep time (TST) was selected as the primary measure of sleep. The sample included 144 women (mean age = 36 [SD = 11.1]) with TMD who displayed at least subclinical insomnia. Sleep was assessed for 14 days using actigraphy which was validated by concurrent sleep diaries. Daily diary assessments of pain-related experiences and affective states were conducted twice per day (ie, once upon participants' waking and the other prior to going to sleep) for the same 14-day period. Multilevel structural equation modeling revealed that both morning pain expectancy (95% CI: -.0004, -.00003) and positive affect (95% CI: -.0005, -.000001) mediated the association between previous night's TST and next-day's overall pain severity, such that shorter previous night TST was associated with higher next-morning pain expectancy and lower positive affect, which in turn were associated with a greater level of next-day's overall pain severity while controlling for morning pain severity. Reducing exaggerated daily pain expectancy and up-regulating positive affect may be important intervention targets for disengaging the sleep-pain link among individuals with co-occurring TMD and sleep disturbance. PERSPECTIVE: The daily link between previous night sleep duration and next day pain severity is mediated by morning pain expectancy and positive affect among women with temporomandibular disorder and sleep disturbance. Reducing pain expectancy and increasing positive affect may serve an important role in improving self-management of chronic pain.

Pain Variability and Subjective Function in Individuals With Patellofemoral Pain: A Short Report

Individuals with patellofemoral pain (PFP) experience discomfort during various functional activities. Long-term pain is a common consequence of PFP, yet little is known about daily pain variability. Our study consisted of 25 individuals with PFP who completed the Anterior Knee Pain Scale (AKPS) and recorded their daily pain over 10 days. Pain was evaluated using 2 measures of intensity (baseline pain, 10-day average pain) and 2 measures of variability (mean square of successive differences, probability of acute change). Associations between AKPS and the 4 pain measures were calculated with Pearson correlations. We calculated a linear regression to examine the amount of variance in the AKPS explained by the 4 pain measures. Greater mean square of successive differences values were moderately associated with lesser AKPS scores (r = -0.648, P < .001). Mean square of successive differences and 10-day averaged pain were the strongest predictors of AKPS (R2 = 0.565, P < .001). Pain variability provided a unique perspective on the pain experience and predicted patient-oriented function in individuals with PFP.