The impact of health literacy: associations with disease activity and medication prescription in patients with rheumatoid arthritis

OBJECTIVE

The aim of this study was to explore the longitudinal associations between health literacy profiles and disease activity and medication prescription in patients with RA.

METHODS

Patients with RA who previously completed the Health Literacy Questionnaire (HLQ) and were assigned 1 of 10 distinct health literacy profiles based on cluster analysis were further aggregated into three groups: 'several health literacy limitations', 'some health literacy limitations' and 'good health literacy'. Linear mixed modelling (LMM) was used to analyse the association between health literacy groups and disease activity over the course of 1 year. Chi-squared tests and logistic regression analyses were used to compare medication prescriptions between the groups.

RESULTS

A total of 108 patients with RA were included. LMM showed a significant effect of health literacy group on disease activity over time (P = 0.010). Patients with 'good health literacy' had significantly lower disease activity over time [28-joint DAS with ESR (DAS28-ESR) = 2.4] than patients with 'several health literacy limitations' (DAS28-ESR = 3.1), independent of age, gender and education level. Patients with 'good health literacy' were most often prescribed a biologic DMARD (50%), whereas patients with 'some health literacy limitations' more commonly received a conventional synthetic DMARD only [72.7%; odds ratio (OR) 4.24], and patients with 'several health literacy limitations' were more often prescribed prednisolone (52.4%; OR 3.56).

CONCLUSION

Significant differences in longitudinal disease activity and medication prescription were observed between groups with different health literacy levels. These results stress the importance of insights into the role of health literacy in treatment and outcomes in patients with RA.

Further evaluation of inflammatory and non-inflammatory aspects of pain in rheumatoid arthritis patients

Objective

A high discrepancy between the number of tender and swollen joints (e.g. ΔTSJ ≥ 7) has previously been used as an indication for the presence of changes in central mechanisms in patients with moderate-to-high disease activity. In this study, we explored whether the ΔTSJ can also be used to obtain insights into the underlying pain mechanisms in patients with on average well-controlled disease activity.

Methods

A 2 year retrospective analysis of routinely obtained 28-joint DAS (DAS28) components was performed on 45 patients with low inflammatory activity at the group level. All patients underwent pressure pain threshold (PPT) and electrical pain threshold (EPT) measurements and completed four self-report questionnaires [short-form 36 (SF-36v2); central sensitization inventory (CSI); generalized pain questionnaire (GPQ); and the pain catastrophizing scale (PCS)].

Results

Patients with a ΔTSJ ≥ 3 at least once in the past 2 years showed significantly lower EPT and PPT values and higher levels of pain and disability on the SF-36v2 compared with the ΔTSJ < 3 group. Furthermore, GPQ scores were significantly higher in those with ΔTSJ ≥ 3, while CSI and PCS scores were similar.

Conclusion

These findings suggest that in patients in the ΔTSJ ≥ 3 group, mechanisms other than inflammation (only) underlie the pain. Moreover, our findings suggest that among the multiple potential underlying psychological mechanisms, pain catastrophizing (as measured by the PCS) and psychological hypervigilance (as measured by the CSI) do not play an important role. These findings could be useful in the clinical management of the patient. Depending on the dominant mechanism underlying the (persistent) pain, patients might respond differently to treatment.

Continuous effectiveness and safety after a hospital-wide switch to adalimumab biosimilar: An observational study in rheumatoid arthritis patients

The objective of this study was to examine the maintenance of effect and safety after a hospital-wide switch for economic reasons from adalimumab originator Humira® to biosimilar Amgevita® in real-world rheumatoid arthritis (RA) patients and patient satisfaction with the switch. We conducted a single-center retrospective observational study of RA patients on the course of their disease activity (DAS28, ESR, and CRP), health-related quality of life (SF-36), and functional disability (HAQ-DI) before and up to 1 year after the switch, supplemented with a cross-sectional survey on satisfaction and experienced side effects approximately 18 months after the switch. Treatment outcomes were analyzed with linear mixed modeling and generalized estimating equations. Of 52 RA patients sufficient data were available. Disease activity levels, the proportion of patients in remission, and SF-36 and HAQ-DI scores did not significantly change from before the switch. Overall, patients were satisfied with the switch. Three patients (7.9%) stopped the biosimilar due to side effects. In conclusion, switching to the adalimumab biosimilar did not result in increased disease activity or worse patient-reported outcomes. Also, there was no apparent evidence of increased side effects. Patients themselves were mostly satisfied with the switching experience.

The effectiveness of a web-based Dutch parenting program to prevent overweight in children 9-13 years of age: Results of a two-armed cluster randomized controlled trial

INTRODUCTION

Although parental support is an important component in programs designed to prevent overweight in children, current programs pay remarkably little attention to the role of parenting. We therefore developed a web-based parenting program entitled "Making a healthy deal with your child". This e-learning program can be incorporated into existing overweight prevention programs. The aim of this study was to determine the effectiveness of this e-learning program.

MATERIALS AND METHODS

The effectiveness was examined in a two-armed cluster randomized controlled trial. The participants were 475 parent-child dyads of children 9-13 years of age in the Netherlands who participated in an existing schoolclass-based overweight prevention program. At the school grade level, parents were randomly assigned to either the intervention or the control condition. Measurements were taken from both parents and children at baseline, and 5 and 12 months after baseline. Primary outcomes included the child's dietary and sedentary behavior, and level of physical activity. Secondary outcomes included general parenting style, specific parenting practices, and parental self-efficacy. Linear mixed effects models and generalized linear mixed effects models were conducted in R.

RESULTS

Intention-to-treat analyses and completers only revealed no significant effects between the intervention and control condition on energy balance-related behaviors of the child and parenting skills after correction for multiple testing. The parents' mean satisfaction with the e-learning program (on a 10-point scale) was 7.0±1.1.

CONCLUSIONS

Although parents were generally satisfied with the parenting program, following this program had no significant beneficial effects regarding the children's energy balance-related behaviors or the parenting skills compared to the control condition. This program may be more beneficial if used by high-risk groups (e.g. parents of children with unhealthy energy balance-related behaviors and/or with overweight) compared to the general population, warranting further study.

Disentangling between- and within-person associations of psychological distress and mental well-being: An experience sampling study examining the dual continua model of mental health among university students

The dual continua model assumes that psychological distress and mental well-being are two related, yet distinct dimensions of mental health. Previous studies did convincingly show the distinctiveness of these two dimensions using mainly cross-sectional research. Despite the importance to distinguish between- and within-person associations in psychological theories, to date, no study specifically distinguished between- and within-person associations for the relationship between distress and well-being. Therefore, the objective of this study was to validate whether the dual continua model actually holds when examined within individuals. Intensive longitudinal data were collected through experience sampling. The sample included 25 university students (mean age = 23.50 years, 56% female), who completed a baseline questionnaire as well as momentary measures of psychological distress and mental well-being three times per day for two weeks. 1,014 timepoints were analyzed using multilevel models and person-mean centering was applied to distinguish between- and within person associations. A significant moderate negative between-person association was found for the relationship between psychological distress and mental well-being (β = -.363, marginal R 2 = 0.15, p < .001). The within-person association was also significant and similar in magnitude (β = -.432, marginal R 2 = 0.18, p < .001) at the group level. Individual within-person associations between distress and well-being varied substantially, but were negative for almost all participants. This study is an important step towards validating the applicability and universality of this widely used model. The current findings provide preliminary evidence that the dual continua model does not only hold between people, but also on the level it is actually used for, namely within individual people.

Exploratory Structural Equation Modeling: Practical Guidelines and Tutorial With a Convenient Online Tool for Mplus

Critics of positive psychology have questioned the validity of positive psychological assessment measures (PPAMs), which negatively affects the credibility and public perception of the discipline. Psychometric evaluations of PPAMs have shown that various instruments produce inconsistent factor structures between groups/contexts/times frames, that their predictive validity is questionable, and that popular PPAMs are culturally biased. Further, it would seem positive psychological researchers prioritize date-model-fit over measurement quality. To address these analytical challenges, more innovative and robust approaches toward the validation and evaluation of PPAMs are required to enhance the discipline's credibility and to advance positive psychological science. Exploratory Structural Equation Modeling (ESEM) has recently emerged as a promising alternative to overcome some of these challenges by incorporating the best elements from exploratory- and confirmatory factor analyses. ESEM is still a relatively novel approach, and estimating these models in statistical software packages can be complex and tedious. Therefore, the purpose of this paper is to provide novice researchers with a practical tutorial on how to estimate ESEM with a convenient online tool for Mplus. Specifically, we aim to demonstrate the use of ESEM through an illustrative example by using a popular positive psychological instrument: the Mental Health Continuum-SF. By using the MHC-SF as an example, we aim to provide (a) a brief overview of ESEM (and different ESEM models/approaches), (b) guidelines for novice researchers on how to estimate, compare, report, and interpret ESEM, and (c) a step-by-step tutorial on how to run ESEM analyses in Mplus with the De Beer and Van Zy ESEM syntax generator. The results of this study highlight the value of ESEM, over and above that of traditional confirmatory factor analytical approaches. The results also have practical implications for measuring mental health with the MHC-SF, illustrating that a bifactor ESEM Model fits the data significantly better than any other theoretical model.

Exploring factors associated with personal recovery in bipolar disorder

BACKGROUND

Personal recovery is increasingly recognized as important outcome for people with bipolar disorder (BD), but research addressing associated factors of personal recovery in this group remains scarce. This study aimed to explore the association of sociodemographic variables, social participation, psychopathology, and positive emotion regulation with personal recovery in BD.

METHODS

Baseline data from a randomized controlled trial and survey data were combined (N = 209) and split into a training (n = 149) and test sample (n = 60). Block-wise regression analyses and model training were used to determine the most relevant predictors. The final parsimonious model was cross-validated in the test sample.

RESULTS

In the final parsimonious model, satisfaction with social roles (β = .442, p < .001), anxiety symptoms (β = -.328, p < .001), manic symptoms (β = .276, p < .001), and emotion-focused positive rumination (β = .258, p < .001) were independently associated with personal recovery. The model explained 57.3% variance in personal recovery (adjusted R²  = .561) and performed well in predicting personal recovery in the independent test sample (adjusted R²  = .491).

CONCLUSIONS

Our findings suggest that especially social participation, anxiety and positive rumination might be relevant treatment targets when aiming to improve personal recovery.

PRACTITIONER POINTS

Personal recovery is considered an increasingly important outcome for people with chronic mental health conditions, including bipolar disorder. We found that anxiety and manic symptoms as well as positive rumination and social participation were independently associated with personal recovery in bipolar disorder. Therefore, these outcomes might be relevant treatment targets when aiming to improve personal recovery in bipolar disorder. Possible interventions to improve these outcomes are discussed, including supported employment and vocational rehabilitation for social participation and exercising with savoring strategies to increase positive rumination.

Impact of sustained remission on quality of life among women with rheumatoid arthritis and systemic lupus erythematosus: a prospective observational study

Background

Health-related quality of life (HRQOL) as a patient reported outcome plays important roles in the life of patients with RA (rheumatoid arthritis) and SLE (Systemic lupus erythematosus) as well as their families. Evaluating the impact of sustained remission on HRQOL is important and could be of potential help in daily practice. Thus, we aimed to assess and compare prospectively the impact of sustained remission on HRQOL in Saudi RA and SLE female cohorts.

Results

Sixty-two female patients with active RA and 34 female patients with active SLE fulfilled the inclusion-, entry- and follow-up criteria. At baseline, the SLE patients had significantly better SF-36 scores than the RA patients. In both groups, significant correlations were found between disease activity and physical (PCS) and mental (MCS) components summary of the SF-36 (all p’s ≤ 0.001). In sustained remission, both SLE and RA patients showed significant improvements of the SF-36 scores (p < 0.001) compared to baseline. RA patients in sustained remission had a significantly better general health, bodily pain and physical functioning, and total PCS scores (p < 0.001) than those with SLE.

Conclusions

Both SLE and RA patients in sustained remission showed strongly improved HRQOL. In sustained remission, RA patients had comparable or better HRQOL than SLE patients.

The relation of fibromyalgia and fibromyalgia symptoms to self-reported seizures

Objective

Several epidemiological and clinical reports associate fibromyalgia (FM) with seizure disorders, and clinical studies associate FM diagnosis with psychogenic non-epileptic seizures. However, these associations rely on self-reports of being diagnosed with FM or unstandardized clinical diagnosis in combination with small samples. We investigated the association of FM and self-reported seizures using a large rheumatic disease databank and the current established self-reported, symptom-based FM diagnostic criteria.

Methods

We selected a random observation from 11,378 subjects with rheumatoid arthritis (RA), 2,390 (21.0%) of whom satisfied 2016 revised criteria for FM. Patients were inquired about the presence of any kind of seizures in the previous 6 months, anti-epileptic medications, and patient-reported symptoms and outcomes.

Results

Seizures were reported by 89 RA patients who met FM criteria (FM+) and by 97 patients who did not (FM-), resulting in an age- and sex-adjusted seizure prevalence of 3.74 (95% CI 2.95 to 4.53) per 100 FM+ subjects and 1.08 (95% CI 0.87 to 1.30) in FM- subjects. The seizure odds ratio of FM+ to FM- cases was 3.54 (95% CI 2.65 to 4.74). Seizures were associated to a very similar degree with symptom reporting (somatic symptom count and comorbidity index) as to FM diagnosis variables. RA patients reporting seizures also reported worse pain, quality of life, and functional status. Seizure patients treated with anti-seizure medication had worse outcomes and more comorbidities than seizure patients with no seizure drugs.

Conclusions

We found a significant and similar association of both FM diagnostic variables and FM-related symptom variables, including the number of symptoms and comorbidities, with self-reported seizures in people with RA. The observed association was similar to those found in previous studies of symptoms variables and seizures and does not suggest a unique role for fibromyalgia diagnosis. Rather, it suggests that multi-symptom comorbidity is linked to seizures in a complex and not yet clearly understood way. As the current study relied on self-reported seizures and was not able to distinguish between epileptic and psychogenic nonepileptic seizures, future studies are needed to replicate the findings using both validated FM criteria assessments and clinically verified diagnoses of epileptic and psychogenic seizures.

Structural Validity of the World Assumption Scale

The World Assumption Scale (WAS) is a frequently used measure in trauma research. The 32 items of the WAS are intended to represent eight assumptions about the benevolence of the world, the meaningfulness of events, and the worthiness of the self. Debate about the validity of the WAS is ongoing, particularly in terms of its empirical factor structure; some studies have confirmed a model of eight correlated factors whereas several other studies have not. The WAS items were administered to a clinical sample of patients who sought professional help because of posttraumatic complaints (n = 1,791) as well as a sample of healthcare professionals (n = 236). We split the clinical sample into three subsamples, then performed exploratory factor analysis using data from one subsample and tested the factor structure with confirmatory factor analysis using the other two subsamples. A consistent model of eight correlated factors was demonstrated, with almost all factors showing acceptable reliability, Cronbach's αs = .68-.84. We tested this factor model against data from the sample of healthcare professionals with increasingly stringent levels of invariance and found it to be scalar invariant (same structure, loadings, and thresholds). In a regression analysis, five factors showed significant associations with posttraumatic stress disorder (PTSD) symptoms, and two factors had unique associations with PTSD symptoms after we controlled for traumatic events: Self-Worth, β = -.31; and Luck, β = -.15. Future research should aim to distinguish between different assumptions and their individual influences on posttraumatic complaints.

B-positive: a randomized controlled trial of a multicomponent positive psychology intervention for euthymic patients with bipolar disorder - study protocol and intervention development

BACKGROUND

Bipolar disorder (BD) is characterized by recurrent (hypo)manic and depressive episodes, alternating with euthymic states in which patients are relatively symptom free. Besides clinical recovery, it is important to also strive for improvement of mental well-being and personal recovery. One prominent field focussing on the improvement of well-being is positive psychology. However, studies assessing the effects of positive psychology or personal recovery interventions for people with BD are scarce and have used weak methodological designs. The study described in this protocol article aims to assess the effectiveness of a multicomponent positive psychology intervention ("Living well with bipolar disorder") adjusted for people with BD in the euthymic phase to improve well-being and personal recovery.

METHOD

The study concerns a pragmatic randomized multicenter trial. The principle objective of the study is to assess whether the positive psychology intervention offered to BD patients in remission in addition to usual care (CAU) is more effective than CAU. The study will include 112 participants randomized to either the experimental condition receiving the intervention in addition to CAU or the control condition receiving CAU. The study population are patients with BD I or II in the euthymic phase. The inclusion criteria are 1) diagnosis of BD I or BD II, 2) between the ages of 18-65, 3) four or more supportive sessions in the last year, and 4) only residual depressive or manic symptoms. Patients are excluded if they are in a depressive or manic episode, have current addiction problems or have optimal levels of well-being. Measurements take place at baseline, post-intervention and follow-up 6 and 12 months from baseline. Outcomes of measures include positive well-being, personal recovery, psychopathology, self-compassion, positive relationships, dampening of positive affect and relapse.

DISCUSSION

The outlined study will be the first RCT examining the effects of a multicomponent positive psychology intervention for patients with bipolar disorder. Several limitations, including generalizability of the results and possible attrition issues, are discussed in advance.

TRIAL REGISTRATION

This study has been registered in the Netherlands Trial Register ( NTR6729 ) on 12 October 2017.

Multi-biomarker disease activity score as a predictor of disease relapse in patients with rheumatoid arthritis stopping TNF inhibitor treatment

Objective

Successfully stopping or reducing treatment for patients with rheumatoid arthritis (RA) in low disease activity (LDA) may improve cost-effectiveness of care. We evaluated the multi-biomarker disease activity (MBDA) score as a predictor of disease relapse after discontinuation of TNF inhibitor (TNFi) treatment.

Methods

439 RA patients who were randomized to stop TNFi treatment in the POET study were analyzed post-hoc. Three indicators of disease relapse were assessed over 12 months: 1) restarting TNFi treatment, 2) escalation of any DMARD therapy and 3) physician-reported flare. MBDA score was assessed at baseline. Associations between MBDA score and disease relapse were examined using univariate analysis and multivariate logistic regression.

Results

At baseline, 50.1%, 35.3% and 14.6% of patients had low (<30), moderate (30−44) or high (>44) MBDA scores. Within 12 months, 49.9% of patients had restarted TNFi medication, 59.0% had escalation of any DMARD and 57.2% had ≥1 physician-reported flare. MBDA score was associated with each indicator of relapse. At least one indicator of relapse was observed in 59.5%, 68.4% and 81.3% of patients with low, moderate or high MBDA scores, respectively (P = 0.004). Adjusted for baseline DAS28-ESR, disease duration, BMI and erosions, high MBDA scores were associated with increased risk for restarting TNFi treatment (OR = 1.85, 95% CI 1.00–3.40), DMARD escalation (OR = 1.99, 95% CI 1.01–3.94) and physician-reported flare (OR = 2.00, 95% 1.06–3.77).

Conclusion

For RA patients with stable LDA who stopped TNFi, a high baseline MBDA score was independently predictive of disease relapse within 12 months. The MBDA score may be useful for identifying patients at risk of relapse after TNFi discontinuation.

The impact of non-response bias due to sampling in public health studies: A comparison of voluntary versus mandatory recruitment in a Dutch national survey on adolescent health

BACKGROUND

In public health monitoring of young people it is critical to understand the effects of selective non-response, in particular when a controversial topic is involved like substance abuse or sexual behaviour. Research that is dependent upon voluntary subject participation is particularly vulnerable to sampling bias. As respondents whose participation is hardest to elicit on a voluntary basis are also more likely to report risk behaviour, this potentially leads to underestimation of risk factor prevalence. Inviting adolescents to participate in a home-sent postal survey is a typical voluntary recruitment strategy with high non-response, as opposed to mandatory participation during school time. This study examines the extent to which prevalence estimates of adolescent health-related characteristics are biased due to different sampling methods, and whether this also biases within-subject analyses.

METHODS

Cross-sectional datasets collected in 2011 in Twente and IJsselland, two similar and adjacent regions in the Netherlands, were used. In total, 9360 youngsters in a mandatory sample (Twente) and 1952 youngsters in a voluntary sample (IJsselland) participated in the study. To test whether the samples differed on health-related variables, we conducted both univariate and multivariable logistic regression analyses controlling for any demographic difference between the samples. Additional multivariable logistic regressions were conducted to examine moderating effects of sampling method on associations between health-related variables.

RESULTS

As expected, females, older individuals, as well as individuals with higher education levels, were over-represented in the voluntary sample, compared to the mandatory sample. Respondents in the voluntary sample tended to smoke less, consume less alcohol (ever, lifetime, and past four weeks), have better mental health, have better subjective health status, have more positive school experiences and have less sexual intercourse than respondents in the mandatory sample. No moderating effects were found for sampling method on associations between variables.

CONCLUSIONS

This is one of first studies to provide strong evidence that voluntary recruitment may lead to a strong non-response bias in health-related prevalence estimates in adolescents, as compared to mandatory recruitment. The resulting underestimation in prevalence of health behaviours and well-being measures appeared large, up to a four-fold lower proportion for self-reported alcohol consumption. Correlations between variables, though, appeared to be insensitive to sampling bias.

Recently diagnosed rheumatoid arthritis patients benefit from a treat-to-target strategy: results from the DREAM registry

Despite considerable evidence on the efficacy and safety of early aggressive treat-to-target (T2T) strategies in early rheumatoid arthritis (RA), a proportion of patients still fail to reach remission. The goal of this study is to examine remission rates and predictors of remission in a real life T2T cohort of consecutive patients with a recent diagnosis of RA. Baseline demographics, clinical, laboratory and patient-reported variables and 1-year follow-up disease activity data were used from patients with early RA included in the DREAM remission induction cohort II study. Survival analyses and simple and multivariable logistic regression analyses were used to examine remission rates and significant predictors of achieving remission. A total of 137 recently diagnosed consecutive RA patients were available for this study. During the first year after inclusion, DAS28 remission was achieved at least once in 77.2 % of the patients and the median time to first remission was 17 weeks. None of the examined baseline variables were robustly associated with achieving remission within 1 year and in the multivariable analysis only lower ESR (p = 0.005) remained significantly associated with achieving fast remission within 17 weeks. During the first year of their disease a high proportion of recently diagnosed RA patient achieved remission, with only a small percentage of patients needing bDMARD therapy. Combined with the absence of baseline predictors of remission, this suggests that clinicians in daily clinical practice may focus on DAS28 scores only, without needing to take other patients characteristics into account.

Acceptance and commitment therapy as a web-based intervention for depressive symptoms: randomised controlled trial

BACKGROUND

Depression is a highly prevalent disorder, causing a large burden of disease and substantial economic costs. Web-based self-help interventions seem promising in promoting mental health.

AIMS

To compare the efficacy of a guided web-based intervention based on acceptance and commitment therapy (ACT) with an active control (expressive writing) and a waiting-list control condition (Netherlands Trial Register NTR1296).

METHOD

Adults with depressive symptoms from the general population were randomised to ACT (n = 82), expressive writing (n = 67) or waiting-list control (n = 87). The main outcome was reduction in depressive symptoms assessed with the Center for Epidemiological Studies - Depression scale.

RESULTS

Significant reductions in depressive symptoms were found following the ACT intervention, compared with the control group (Cohen's d = 0.56) and the expressive writing intervention (d = 0.36). The effects were sustained at 6-month and 12-month follow-up.

CONCLUSIONS

Acceptance and commitment therapy as a web-based public mental health intervention for adults with depressive symptoms can be effective and applicable.

Neuropathic-like pain features and cross-sectional associations in rheumatoid arthritis

INTRODUCTION

Increasing evidence indicates that features suggestive of neuropathic pain may also be present in patients with common rheumatic conditions. The objective of this study was to examine neuropathic-like pain symptoms and associated factors in patients with rheumatoid arthritis.

METHODS

We used the painDETECT screening tool to identify possible or likely neuropathic pain in 159 outpatients with rheumatoid arthritis. Patients additionally completed other self-reported measures, while clinical measures were assessed to calculate the 28-joint Disease Activity Score. Univariate analyses and multivariable logistic regression were used to identify factors associated with neuropathic pain features.

RESULTS

According to the painDETECT, 27 patients (17.0 %) were classified as having likely neuropathic pain and 34 patients (21.4 %) as having possible neuropathic pain. Besides reporting more severe pain, patients with likely or possible neuropathic pain were more likely to meet the diagnostic criteria for fibromyalgia, to use analgesics, and to have more tender joints and a worse physical and mental health status as measured by the 36-item Short-Form health survey. In multivariable analysis, physical (P < 0.001) and mental health status (P = 0.006) remained significantly associated with neuropathic pain features, even after controlling for pain severity.

CONCLUSIONS

These findings suggest that a sizeable proportion of patients with relatively well-controlled rheumatoid arthritis report symptoms suggestive of neuropathic pain. Neuropathic-like pain symptoms are independently associated with worse self-reported physical and mental health.

Assessment of Fatigue in Rheumatoid Arthritis: A Psychometric Comparison of Single-item, Multiitem, and Multidimensional Measures

Objective.

To compare the psychometric functioning of multidimensional disease-specific, multiitem generic, and single-item measures of fatigue in patients with rheumatoid arthritis (RA).

Methods.

Confirmatory factor analysis (CFA) and longitudinal item response theory (IRT) modeling were used to evaluate the measurement structure and local reliability of the Bristol RA Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ), the Medical Outcomes Study Short Form-36 (SF-36) vitality scale, and the BRAF Numerical Rating Scales (BRAF-NRS) in a sample of 588 patients with RA.

Results.

A 1-factor CFA model yielded a similar fit to a 5-factor model with subscale-specific dimensions, and the items from the different instruments adequately fit the IRT model, suggesting essential unidimensionality in measurement. The SF-36 vitality scale outperformed the BRAF-MDQ at lower levels of fatigue, but was less precise at moderate to higher levels of fatigue. At these levels of fatigue, the living, cognition, and emotion subscales of the BRAF-MDQ provide additional precision. The BRAF-NRS showed a limited measurement range with its highest precision centered on average levels of fatigue.

Conclusion.

The different instruments appear to access a common underlying domain of fatigue severity, but differ considerably in their measurement precision along the continuum. The SF-36 vitality scale can be used to measure fatigue severity in samples with relatively mild fatigue. For samples expected to have higher levels of fatigue, the multidimensional BRAF-MDQ appears to be a better choice. The BRAF-NRS are not recommended if precise assessment is required, for instance in longitudinal settings.

How age and sex affect the erythrocyte sedimentation rate and C-reactive protein in early rheumatoid arthritis

BACKGROUND

The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are two commonly used measures of inflammation in rheumatoid arthritis (RA). As current RA treatment guidelines strongly emphasize early and aggressive treatment aiming at fast remission, optimal measurement of inflammation becomes increasingly important. Dependencies with age, sex, and body mass index have been shown for both inflammatory markers, yet it remains unclear which inflammatory marker is affected least by these effects in patients with early RA.

METHODS

Baseline data from 589 patients from the DREAM registry were used for analyses. Associations between the inflammatory markers and age, sex, and BMI were evaluated first using univariate linear regression analyses. Next, it was tested whether these associations were independent of a patient's current disease activity as well as of each other using multiple linear regression analyses with backward elimination. The strengths of the associations were compared using standardized beta (β) coefficients. The multivariate analyses were repeated after 1 year.

RESULTS

At baseline, both the ESR and CRP were univariately associated with age, sex, and BMI, although the association with BMI disappeared in multivariate analyses. ESR and CRP levels significantly increased with age (β-ESR=0.017, p<0.001 and β-CRP=0.009, p=0.006), independent of the number of tender and swollen joints, general health, and sex. For each decade of aging, ESR and CRP levels became 1.19 and 1.09 times higher, respectively. Furthermore, women demonstrated average ESR levels that were 1.22 times higher than that of men (β=0.198, p=0.007), whereas men had 1.20 times higher CRP levels (β=-0.182, p=0.048). Effects were strongest on the ESR. BMI became significantly associated with both inflammatory markers after 1 year, showing higher levels with increasing weight. Age continued to be significantly associated, whereas sex remained only associated with the ESR level.

CONCLUSIONS

Age and sex are independently associated with the levels of both acute phase reactants in early RA, emphasizing the need to take these external factors into account when interpreting disease activity measures. BMI appears to become more relevant at later stages of the disease.

Further optimization of the reliability of the 28-joint disease activity score in patients with early rheumatoid arthritis

BACKGROUND

The 28-joint Disease Activity Score (DAS28) combines scores on a 28-tender and swollen joint count (TJC28 and SJC28), a patient-reported measure for general health (GH), and an inflammatory marker (either the erythrocyte sedimentation rate [ESR] or the C-reactive protein [CRP]) into a composite measure of disease activity in rheumatoid arthritis (RA). This study examined the reliability of the DAS28 in patients with early RA using principles from generalizability theory and evaluated whether it could be increased by adjusting individual DAS28 component weights.

METHODS

Patients were drawn from the DREAM registry and classified into a "fast response" group (N = 466) and "slow response" group (N = 80), depending on their pace of reaching remission. Composite reliabilities of the DAS28-ESR and DAS28-CRP were determined with the individual components' reliability, weights, variances, error variances, correlations and covariances. Weight optimization was performed by minimizing the error variance of the index.

RESULTS

Composite reliabilities of 0.85 and 0.86 were found for the DAS28-ESR and DAS28-CRP, respectively, and were approximately equal across patients groups. Component reliabilities, however, varied widely both within and between sub-groups, ranging from 0.614 for GH ("slow response" group) to 0.912 for ESR ("fast response" group). Weight optimization increased composite reliability even further. In the total and "fast response" groups, this was achieved mostly by decreasing the weight of the TJC28 and GH. In the "slow response" group, though, the weights of the TJC28 and SJC28 were increased, while those of the inflammatory markers and GH were substantially decreased.

CONCLUSIONS

The DAS28-ESR and the DAS28-CRP are reliable instruments for assessing disease activity in early RA and reliability can be increased even further by adjusting component weights. Given the low reliability and weightings of the general health component across subgroups it is recommended to explore alternative patient-reported outcome measures for inclusion in the DAS28.

Validity of summing painful joint sites to assess joint-pain comorbidity in hip or knee osteoarthritis

BACKGROUND

Previous studies in patients with hip and knee osteoarthritis (OA) have advocated the relevance of assessing the number of painful joint sites, other than the primary affected joint, in both research and clinical practice. However, it is unclear whether joint-pain comorbidities can simply be summed up.

METHODS

A total of 401 patients with hip or knee OA completed questionnaires on demographic variables and joint-pain comorbidities. Rasch analysis was performed to evaluate whether a sum score of joint-pain comorbidities can be calculated.

RESULTS

Self-reported joint-pain comorbidities showed a good fit to the Rasch model and were not biased by gender, age, disease duration, BMI, or patient group. As a group, joint-pain comorbidities covered a reasonable range of severity levels, although the sum score had rather low reliability levels suggesting it cannot discriminate well among patients.

CONCLUSIONS

Joint-pain comorbidities, in other than the primary affected joints, can be summed into a joint pain comorbidity score. Nevertheless, its use is discouraged for individual decision making purposes since its lacks discriminative power in patients with minimal or extreme joint pain.

Crosscultural measurement equivalence of the Health Assessment Questionnaire II

OBJECTIVE

To evaluate the crosscultural measurement equivalence of the US and Dutch Health Assessment Questionnaire II (HAQ-II) in rheumatoid arthritis (RA).

METHODS

Item response theory (IRT) analyses were performed on US (n = 18,747) and Dutch (n = 1,022) HAQ-II data to evaluate the equivalence of crosscultural item performance. The observed inconsistencies were modeled by assigning country-specific item parameters to biased items. The impact of crosscultural item bias on the comparability of the Dutch and US total scores was analyzed by evaluating the agreement between physical function levels estimated from an IRT model with country-specific item parameters for biased items and physical function levels estimated from the original model that did not account for cultural bias.

RESULTS

Two items showed significant crosscultural bias. However, the agreement in physical function estimates between the respecified and original models was very high, with an intraclass correlation coefficient >0.99 and Bland-Altman limits of agreement ranging from -0.08 to -0.01 on a latent scale with a mean of 0 and an SD of 1.

CONCLUSION

This study suggests that the Dutch and US HAQ-II produce total scores that can be interpreted interchangeably across countries in RA studies, despite some minor bias at the item level.

Validation of the Dutch functional, communicative and critical health literacy scales

OBJECTIVE

While most existing health literacy (HL) measures focus primarily on reading comprehension, the functional, communicative and critical HL scales from Ishikawa et al. [19] aim to measure a broader HL spectrum. The objective of this study was to evaluate the validity of the Dutch translation of this instrument.

METHODS

Two survey studies (n = 79 and n = 209) and one cognitive interview study (n = 18) were performed among samples of breast cancer patients and patients with rheumatic diseases.

RESULTS

Analyses showed the scales measured three distinct factors and convergent validity was satisfactory for communicative and critical HL. Nevertheless, the comprehension of the items and the suitability of the response options raised some problems.

CONCLUSION

The HL scales seem promising to measure a broad definition of HL. By revising some of the items and response options as proposed in this article, the scale will become more understandable for people with low HL skills, which might increase the content validity and the distributional properties of the scale.

PRACTICE IMPLICATIONS

The scale should be revised and revalidated. An improved version should be used in practice to gain insight into HL levels of patients. This will help to develop suitable education programs for people with low HL skills.

Further validation of the 5-item Perceived Efficacy in Patient-Physician Interactions (PEPPI-5) scale in patients with osteoarthritis

OBJECTIVE

To examine the structural validity, internal consistency, test-retest reliability, and construct validity of the 5-item Perceived Efficacy in Patient-Physician Interactions (PEPPI-5) scale in patients with osteoarthritis (OA).

METHODS

A cross-sectional sample of 224 outpatients with OA completed a survey containing the Dutch PEPPI-5 and other standardized measures assessing perceived health-management skills, general self-efficacy, social support, and health-related quality of life. A subsample of 100 patients completed the PEPPI-5 again approximately 3 weeks later.

RESULTS

Confirmatory factor analysis demonstrated good fit for a unidimensional model of the PEPPI-5. Additionally, the scale showed high internal consistency (α=0.92) and fair test-retest reliability (ICC=0.68). As hypothesized, the PEPPI-5 was strongly correlated with perceived health-management skills, moderately with social support and psychosocial aspects of health, and not with physical aspects of health. Contrary to expectations, however, it was not correlated with general self-efficacy.

CONCLUSION

The Dutch PEPPI-5 demonstrated adequate validity and reliability in patients with OA.

PRACTICE IMPLICATIONS

The PEPPI-5 is a brief and appropriate tool for measuring self-efficacy of patients with OA to interact with their physicians. Additional research into its sensitivity to change is needed before it can be confidently recommended as an outcome measure in intervention studies.

Translation and validation of the Dutch version of the Effective Consumer Scale (EC-17)

PURPOSE

The Effective Consumer Scale (EC-17) measures the skills of musculoskeletal patients in managing their own healthcare. The objectives of this study were to translate the EC-17 into Dutch and to further evaluate its psychometric properties.

METHODS

The EC-17 was translated and cognitively pretested following cross-cultural adaptation guidelines. Two hundred and thirty-eight outpatients (52 % response rate) with osteoarthritis or fibromyalgia completed the EC-17 along with other validated measures. Three weeks later, 101 patients completed the EC-17 again.

RESULTS

Confirmatory factor analysis supported the unidimensional structure of the scale. The items adequately fit the Rasch model and only one item demonstrated differential item functioning. Person reliability was high (0.92), but item difficulty levels tended to cluster around the middle of the scale, and measurement precision was highest for moderate and lower levels of skills. The scale demonstrated adequate test-retest reliability (ICC = 0.71), and correlations with other measures were largely as expected.

CONCLUSION

The results supported the validity and reliability of the Dutch version of the EC-17, but suggest that the scale is best targeted at patients with relatively low levels of skills. Future studies should further examine its sensitivity to change in a clinical trial specifically aimed at improving effective consumer skills.

Measurement properties of physical function scales validated for use in patients with rheumatoid arthritis: a systematic review of the literature

Background

The aim of this study was to systematically review the content validity and measurement properties of all physical function (PF) scales which are currently validated for use with patients with rheumatoid arthritis (RA).

Methods

Systematic literature searches were performed in the Scopus and PubMed databases to identify articles on the development or psychometric evaluation of PF scales for patients with RA. The content validity of included scales was evaluated by linking their items to the International Classification of Functioning Disability and Health (ICF). Furthermore, available evidence of the reliability, validity, responsiveness, and interpretability of the included scales was rated according to published quality criteria.

Results

The search identified 26 questionnaires with PF scales. Ten questionnaires were rated to have adequate content validity. Construct validity, internal consistency, test-retest reliability and responsiveness was rated favourably for respectively 15, 11, 5, and 6 of the investigated scales. Information about the absolute measurement error and minimal important change scores were rarely reported.

Conclusion

Based on this literature review, the disease-specificHAQ and the generic SF-36 can currently be most confidently recommended to measure PF in RA for most research purposes. The HAQ, however, was frequently associated with considerable ceiling effects while the SF-36 has limited content coverage. Alternative scales that might be better suited for specific research purposes are identified along with future directions for research.

Validating the 28-tender joint count using item response theory

OBJECTIVE

To examine the construct validity of the 28-tender joint count (TJC-28) using item response theory (IRT)-based methods.

METHODS

A total of 457 patients with early stage rheumatoid arthritis (RA) were included. Internal construct validity of the TJC-28 was evaluated by determining whether the TJC-28 fit a 2-measure logistic IRT model. As well, we tested whether the discrimination and difficulty parameters of the joints properly reflected the known left-right symmetry of joint involvement. External validity was evaluated by correlations with other established measures of disease activity, including pain, disability, general health, erythrocyte sedimentation rate (ESR), and the 28-swollen joint count.

RESULTS

The TJC-28 showed a good fit with the 2-parameter logistic model, with no relevant differential item functioning across sex, age, and time and with excellent reliability. The 28 joints covered a reasonable range of disease activity, even though they were mainly targeted at patients with moderate or high disease activity levels. The joint parameters reflected the left-right symmetry of joint involvement for all pairs of joints except one. All disease activity measures, except ESR, were significantly correlated with the TJC-28. Most correlations were of the expected magnitude.

CONCLUSION

The TJC-28 showed good internal and acceptable external construct validity for patients with early-stage RA. The IRT analyses did point to some potential limitations of the instrument, a major problem being its limited measurement range. Future research should examine whether instrument modifications might lead to a more robust assessment of disease activity in patients with RA.

Psychometric Properties of the Five Facet Mindfulness Questionnaire in Depressed Adults and Development of a Short Form

In recent years, there has been a growing interest in therapies that include the learning of mindfulness skills. The 39-item Five Facet Mindfulness Questionnaire (FFMQ) has been developed as a reliable and valid comprehensive instrument for assessing different aspects of mindfulness in community and student samples. In this study, the psychometric properties of the Dutch FFMQ were assessed in a sample of 376 adults with clinically relevant symptoms of depression and anxiety. Construct validity was examined with confirmatory factor analyses and by relating the FFMQ to measures of psychological symptoms, well-being, experiential avoidance, and the personality factors neuroticism and openness to experience. In addition, a 24-item short form of the FFMQ (FFMQ-SF) was developed and assessed in the same sample and cross-validated in an independent sample of patients with fibromyalgia. Confirmatory factor analyses showed acceptable model fit for a correlated five-factor structure of the FFMQ and good model fit for the structure of the FFMQ-SF. The replicability of the five-factor structure of the FFMQ-SF was confirmed in the fibromyalgia sample. Both instruments proved highly sensitive to change. It is concluded that both the FFMQ and the FFMQ-SF are reliable and valid instruments for use in adults with clinically relevant symptoms of depression and anxiety.

Evaluating the psychometric properties of the Mental Health Continuum-Short Form (MHC-SF)

There is a growing consensus that mental health is not merely the absence of mental illness, but it also includes the presence of positive feelings (emotional well-being) and positive functioning in individual life (psychological well-being) and community life (social well-being). We examined the structure, reliability, convergent validity, and discriminant validity of the Mental Health Continuum-Short Form (MHC-SF), a new self-report questionnaire for positive mental health assessment. We expected that the MHC-SF is reliable and valid, and that mental health and mental illness are 2 related but distinct continua. This article draws on data of the LISS panel of CentERdata, a representative panel for Longitudinal Internet Studies for the Social Sciences (N = 1,662). Results revealed high internal and moderate test-retest reliability. Confirmatory factor analysis (CFA) confirmed the 3-factor structure in emotional, psychological, and social well-being. These subscales correlated well with corresponding aspects of well-being and functioning, showing convergent validity. CFA supported the hypothesis of 2 separate yet related factors for mental health and mental illness, showing discriminant validity. Although related to mental illness, positive mental health is a distinct indicator of mental well-being that is reliably assessed with the MHC-SF.

Application of the health assessment questionnaire disability index to various rheumatic diseases

Purpose

To investigate whether the Stanford Health Assessment Questionnaire Disability Index (HAQ-DI) can serve as a generic instrument for measuring disability across different rheumatic diseases and to propose a scoring method based on item response theory (IRT) modeling to support this goal.

Methods

The HAQ-DI was administered to a cross-sectional sample of patients with confirmed rheumatoid arthritis (n = 619), osteoarthritis (n = 125), or gout (n = 102). The results were analyzed using the generalized partial credit model as an IRT model.

Results

It was found that 4 out of 8 item categories of the HAQ-DI displayed substantial differential item functioning (DIF) over the three diseases. Further, it was shown that this DIF could be modeled using an IRT model with disease-specific item parameters, which produces measures that are comparable for the three diseases.

Conclusion

Although the HAQ-DI partially functioned differently in the three disease groups, the measurement regarding the disability level of the patients can be made comparable using IRT methods.

Confirmatory factor analysis of the Arthritis Impact Measurement Scales 2 short form in patients with rheumatoid arthritis

OBJECTIVE

To examine the factorial validity of the short form Arthritis Impact Measurement Scales 2 (AIMS2-SF) in patients with rheumatoid arthritis (RA).

METHODS

Data were from a sample of 279 patients with active RA who completed the long form AIMS2 before starting treatment with tumor necrosis factor alpha-blocking agents. Confirmatory factor analyses were conducted to test and compare the fit of the currently used theoretical measurement model of the AIMS2-SF, originally suggested for the long form AIMS2, and 2 alternative models based on previous exploratory research.

RESULTS

A model with the physical dimension divided into upper and lower body limitations was superior to the current model, and both models provided a clearly better fit than a model without a separate symptom dimension. Under the restrictive assumption of uncorrelated error terms, none of the models achieved a consistent and acceptable fit as judged by several goodness-of-fit indices. Allowing error covariances between 6 pairs of items within the same dimension resulted in an improved and acceptable fit of both the current model and the model with a separate upper and lower body component.

CONCLUSION

This study generally supports the factorial validity of the AIMS2-SF and suggests the use of separate scores for upper and lower body limitations. Further research is needed to resolve the issue of high error correlations associated with particular items.

Comparison of internal and external responsiveness of the generic Medical Outcome Study Short Form-36 (SF-36) with disease-specific measures in rheumatoid arthritis

OBJECTIVE

To examine the comparative internal and external responsiveness of the generic Medical Outcome Study Short Form-36 Health Survey (SF-36) and disease-specific measures in patients with rheumatoid arthritis (RA).

METHODS

Data were collected from 280 RA patients starting anti-tumor necrosis factor treatment. A total of 168 patients completed a questionnaire including the SF-36, the Arthritis Impact Measurement Scales 2 (AIMS2), the Health Assessment Questionnaire (HAQ), a visual analog scale for general health (VAS-GH), and an 11-point numerical rating scale for pain (NRS pain) at baseline and after 12 months. Internal responsiveness was evaluated with paired samples t-tests and standardized response means (SRM). External responsiveness was investigated with receiver-operating characteristic statistics and Spearman rank-order correlation coefficients. A health transition item was used as the external indicator of change.

RESULTS

No significant differences in internal and external responsiveness were found between the SF-36 and disease-specific measures within the domains physical function, pain, and psychological function. In the domain social function, the SF-36 was more responsive than the AIMS2. In the domain general health, the SF-36 was less responsive (only internal) than the AIMS2 and VAS-GH.

CONCLUSION

Our study showed comparable internal and external responsiveness of the SF-36 compared with disease-specific measures (AIMS2, HAQ, NRS pain) in all health domains, except social function and general health domains. The assumption that disease-specific measures are more responsive to detect intervention-related changes over time is not confirmed by our data.

A Cross-Cultural Study of Pain Intensity in Egyptian and Dutch Women With Rheumatoid Arthritis

It has been suggested that patients from Mediterranean cultures tend to report more intense pain than their Northern or Western European counterparts in comparable medical conditions. However, empirical data to support this hypothesis are limited. The goals of the present study were to examine differences in pain intensity reports between Dutch and Egyptian women with rheumatoid arthritis (RA) and to examine the influence of possible confounding variables using multivariate analyses. We performed a cross-sectional study in 30 Dutch and 42 Egyptian women with comparable RA, matched for age and disease duration. Pain intensity was measured on a 100-mm graphic rating scale. Additionally, we assessed physical function, radiographic joint damage, progression of RA, disease activity, number of swollen and tender joints, medication, rheumatoid factor, and socioeconomic variables. The progression of RA and radiographic damage were not significantly different between Egyptian and Dutch patients. However, the Egyptian population reported significantly worse pain and physical function and demonstrated higher disease activity. Multiple linear regression analysis showed that the country of residence and the number of tender and swollen joints were significant independent determinants of pain reports. The results provide some support for the idea that there are ethnocultural differences in pain reports between Egyptian and Dutch women with RA, although the mechanisms underlying these differences remain unclear.

PERSPECTIVE

This article shows that after controlling for differences in demographic, socioeconomic, and clinical variables, Egyptian women with RA reported more pain than Dutch women with RA. Clinicians and investigators should recognize that cultural or ethnic factors may play an important role in patients' pain reports.

Changes in priorities for improvement in patients with rheumatoid arthritis during 1 year of anti-tumour necrosis factor treatment

OBJECTIVES

To examine priorities for health status improvement in patients with active rheumatoid arthritis (RA) during anti-tumour necrosis factor (TNF) treatment.

METHODS

Data were used from 173 patients with RA starting treatment with TNF-blocking agents. Outcome measures included assessment of health status with the Arthritis Impact Measurement Scales 2 (AIMS2) at baseline and after 3 and 12 months. The AIMS2 contains a priority list from which patients are asked to select from 12 areas of health the 3 in which they would most like to see improvement.

RESULTS

After 1 year of treatment, 10 out of 12 areas of health on the AIMS2 were significantly improved. The most commonly selected priorities for improvement at baseline were pain (88%), hand and finger function (57%), walking and bending (42%), mobility (33%), and work (29%). At group level, this priority ranking remained largely unchanged during treatment. After adjustment for multiple comparisons, only pain was selected significantly less often at 3 and 12 months (71% at both assessments). Within individual patients, however, priorities often changed. Changes in the priority of pain were related to the achieved level of patient-perceived pain and disease activity.

CONCLUSIONS

This study shows that, at the group level, patients' priorities for improvement are fairly stable during 12 months of anti-TNF therapy, despite major improvements in health status. Although pain reduction becomes somewhat less important, it remains the most commonly selected priority. In contrast, individual patient priorities are not stable over the course of treatment and appear to be associated with differences in disease state.

The Validity and Reliability of the Graphic Rating Scale and Verbal Rating Scale for Measuring Pain Across Cultures: A Study in Egyptian and Dutch Women With Rheumatoid Arthritis

OBJECTIVE

To compare the validity and reliability of a graphic rating scale (GRS) and a verbal rating scale (VRS) for measuring pain intensity in young female Egyptian and Dutch patients with rheumatoid arthritis (RA).

METHODS

Data were obtained in a cross-cultural study of 42 Egyptian and 30 Dutch female outpatients with stable RA. Construct validity was assessed by correlating the scales with other core measures of disease activity in RA. Test-retest reliability was assessed over a 1-week interval.

RESULTS

The GRS and the VRS were strongly intercorrelated in the total study cohort and in the Egyptian and Dutch subgroups. In the individual subgroups, only the GRS demonstrated the expected pattern of correlations with other disease activity measures. Test-retest reliability of the GRS was adequate in both Egyptian and Dutch patients (intraclass correlation coefficient 0.78 vs. 0.83, respectively), whereas reliability of the VRS was unsatisfactory in the Egyptian subgroup (weighted kappa 0.60 vs. 0.82 in the Netherlands).

DISCUSSION

The study confirmed that the GRS and VRS were reliable and valid in the total study cohort. Within the individual countries, the GRS seemed to perform better than the VRS.

Patient-perceived satisfactory improvement (PPSI): interpreting meaningful change in pain from the patient's perspective

The assessment of clinically meaningful changes in patient-reported pain has become increasingly important when interpreting results of clinical studies. However, proposed response criteria, such as the minimal clinically important difference, do not correspond with the growing need for information on truly meaningful, individual improvements. The aim of the present study was to investigate satisfactory improvements in pain from the patient's perspective. Data were collected in a 2-week prospective study of 181 arthritis patients treated with a local corticosteroid injection. Baseline and follow-up pain were assessed on 100mm visual analogue scales for pain intensity (VAS-PI). At baseline, patients also marked a hypothetical level on a VAS-PI representing a satisfactory improvement in pain. Patient-perceived satisfactory improvement (PPSI) was constructed using a 5-point categorical rating of change scale at follow-up as the anchor. PPSI was associated with a minimal reduction of 30mm or 55% on the VAS-PI. Since absolute change in pain associated with satisfactory improvement proved highly dependent on baseline pain, percent change scores performed better in classifying improved patients. The 55% threshold for satisfactory improvement was consistent over the course of treatment and reasonably consistent across groups of patients. Our data suggest that PPSI is a clinically relevant and stable concept for interpreting truly meaningful improvements in pain from the individual perspective.