Repeated measures in rheumatoid arthritis reduced the required sample size in a two-armed clinical trial

Sample size calculations for randomized controlled trials with repeatedly measured continuous variables as primary outcomes need improvements: a cross-sectional study

OBJECTIVES

Randomized controlled trials (RCTs) with repeatedly measured continuous variables as primary outcomes are common. Although statistical methodologies for calculating sample sizes in such trials have been extensively investigated, their practical application remains unclear. This study aims to provide an overview of sample size calculation methods for different research questions (e.g., key time point treatment effect, treatment effect change over time) and evaluate the adequacy of current practices in trial design.

STUDY DESIGN AND SETTING

We conducted a comprehensive search of PubMed to identify RCTs published in core journals in 2019 that utilized repeatedly measured continuous variables as their primary outcomes. Data were extracted using a predefined questionnaire including general study characteristics, primary outcomes, detailed sample size calculation methods, and methods for analyzing the primary outcome. We re-estimated the sample size for trials that provided all relevant parameters.

RESULTS

A total of 168 RCTs were included, with a median of four repeated measurements (interquartile range 3-6) per outcome. In 48 (28.6%) trials, the primary outcome used for sample size calculation differed from the one used in defining the primary outcomes. There were 90 (53.6%) trials exhibited inconsistencies between the hypotheses specified for sample size calculation and those specified for primary analysis. The statistical methods used for sample size calculation in 158 (94.0%) trials did not align with those used for primary analysis. Additionally, only 6 (3.6%) trials accounted for the number of repeated measurements, and 7 (4.2%) trials considered the correlation among these measurements when calculating the sample size. Furthermore, of the 128 (76.2%) trials that considered loss to follow-up, 33 (25.8%) used an incorrect formula (i.e., N∗(1+lose rate) for sample size adjustment. In 53 (49.5%) out of 107 trials, the re-estimated sample size was larger than the reported sample size.

CONCLUSION

The practice of sample size calculation for RCTs with repeatedly measured continuous variables as primary outcomes displayed significant deficiencies, with a notable proportion of trials failed to report essential parameters about repeated measurement required for sample size calculation. Our findings highlight the urgent need to use optimal sample size methods that align with the research hypothesis, primary analysis method, and the form of the primary outcome.

Longitudinal in vivo monitoring of axonal degeneration after brain injury

Traumatic brain injury (TBI)-induced axonal degeneration leads to acute and chronic neuropsychiatric impairment, neuronal death, and accelerated neurodegenerative diseases of aging, including Alzheimer's and Parkinson's diseases. In laboratory models, axonal degeneration is traditionally studied through comprehensive postmortem histological evaluation of axonal integrity at multiple time points. This requires large numbers of animals to power for statistical significance. Here, we developed a method to longitudinally monitor axonal functional activity before and after injury in vivo in the same animal over an extended period. Specifically, after expressing an axonal-targeting genetically encoded calcium indicator in the mouse dorsolateral geniculate nucleus, we recorded axonal activity patterns in the visual cortex in response to visual stimulation. In vivo aberrant axonal activity patterns after TBI were detectable from 3 days after injury and persisted chronically. This method generates longitudinal same-animal data that substantially reduces the number of required animals for preclinical studies of axonal degeneration.

Aquatic Exercises were Associated with an Acceptable State of Symptoms in Patients with Inflammatory Rheumatic Diseases: Results from a Study with Interrupted Time-Series Design

AIM OF STUDY

The aim of this study was two-fold: to compare symptoms and daily activity in patients with inflammatory rheumatic diseases across periods with and without aquatic exercises, and to examine whether the patients reached an acceptable state of symptoms during the periods with aquatic exercises.

METHODS

Thirty-six patients reported pain, fatigue, stiffness and ability to carry out daily activities across periods with and without aquatic exercises. The study has an interrupted time-series design and variables were collected with text messages on mobile phones twice a week over a period of 35 weeks.

RESULTS

There was a significant reduction in pain, fatigue, stiffness and enhanced level of daily activity (p > 0.05) during periods of aquatic exercises compared to periods without. Further, a significantly higher proportion of patients reached an acceptable state for both pain and fatigue during periods with aquatic exercises.

CONCLUSIONS

Living with an inflammatory rheumatic disease is a lifelong challenge. Pain and fatigue are considered major obstacles for daily functioning and adequate self-management strategies are requested. Based on the high proportion of patients reporting to be in an acceptable state of both pain and fatigue during periods with aquatic exercises, the intervention should be regarded as an important self-management tool rather than a treatment option assuming long-lasting effects. Copyright © 2014 John Wiley & Sons, Ltd.

Collection of patient-reported outcomes;--text messages on mobile phones provide valid scores and high response rates

Background

Patients with inflammatory rheumatic diseases have expressed a need for more frequent measurement of relevant outcomes, due to the variations in their symptoms during the day and from day to day. At present, patient-reported outcomes are extensively collected with questionnaires completed with pen and paper. However, as a measurement tool in frequent data collection the questionnaires are impractical. In contrast, text messages on mobile phones are suitable for frequent data collection.

The aim of this study was two-fold; to compare daily registrations of patient-reported outcomes assessed with text-messages on mobile phones (SMS) or with questionnaires completed with pen and paper (P&P), with regard to scores and variation of scores, and to examine feasibility of the SMS method in a multicentre clinical study.

Methods

To compare scores, 21 patients with an inflammatory, rheumatic disease performed daily assessments of pain, fatigue, stiffness and ability to carry out daily activities on a numeric rating scale (NRS). The patients were asked to assess the variables every other day with the SMS method and every other day with the P&P method for 28 consecutive days. In total each participant had to answer 14 P&P forms and 14 SMS messages. Mean scores and variation, expressed as the pooled standard deviation or as the average range between the maximum and minimum scores for the two methods, were compared using paired sample t-tests or Wilcoxon Signed Rank Test. To examine feasibility, 36 patients with an inflammatory, rheumatic disease assessed the same four variables with SMS twice a week for 35 weeks. Feasibility of the SMS method was expressed as mean response-rate (%) in the total group and per centre.

Results

Mean scores, standard deviation of mean scores and mean range scores did not differ significantly between the two methods (p > 0.05). Response-rate with the SMS method was 97.9% for the whole group and for the three centres 97.1%, 98.3% and 98.4%, respectively.

Conclusion

Outcomes assessed on numeric rating scales and reported with text-messages on mobile phones or with questionnaires completed with pen and paper provide comparable scores. Further, the SMS method provided high response rates (> 97%) in a multicentre setting. Our results encourage the use of text messages on mobile phones in studies requiring frequent data collection and real-time assessment, as in fluctuating diseases such inflammatory, rheumatic diseases.

Two to five repeated measurements per patient reduced the required sample size considerably in a randomized clinical trial for patients with inflammatory rheumatic diseases

Background

Patient reported outcomes are accepted as important outcome measures in rheumatology. The fluctuating symptoms in patients with rheumatic diseases have serious implications for sample size in clinical trials. We estimated the effects of measuring the outcome 1-5 times on the sample size required in a two-armed trial.

Findings

In a randomized controlled trial that evaluated the effects of a mindfulness-based group intervention for patients with inflammatory arthritis (n=71), the outcome variables Numerical Rating Scales (NRS) (pain, fatigue, disease activity, self-care ability, and emotional wellbeing) and General Health Questionnaire (GHQ-20) were measured five times before and after the intervention. For each variable we calculated the necessary sample sizes for obtaining 80% power (α=.05) for one up to five measurements.

Two, three, and four measures reduced the required sample sizes by 15%, 21%, and 24%, respectively. With three (and five) measures, the required sample size per group was reduced from 56 to 39 (32) for the GHQ-20, from 71 to 60 (55) for pain, 96 to 71 (73) for fatigue, 57 to 51 (48) for disease activity, 59 to 44 (45) for self-care, and 47 to 37 (33) for emotional wellbeing.

Conclusions

Measuring the outcomes five times rather than once reduced the necessary sample size by an average of 27%. When planning a study, researchers should carefully compare the advantages and disadvantages of increasing sample size versus employing three to five repeated measurements in order to obtain the required statistical power.

ABCB1andABCC3Gene Polymorphisms Are Associated with First-year Response to Methotrexate in Juvenile Idiopathic Arthritis

Objective.

Although methotrexate (MTX) is the most widely prescribed drug in juvenile idiopathic arthritis (JIA), 30% of patients fail to respond to it. To individualize treatment strategies, the genetic determinants of response to MTX should be identified.

Methods.

A cohort of 287 patients with JIA treated with MTX was studied longitudinally over the first year of treatment. MTX response was defined as the American College of Rheumatology pediatric 70 criteria (ACRped70). We genotyped 21 single-nucleotide polymorphisms in 13 genes related to MTX polyglutamylation and to cellular MTX uptake and efflux. Potential associations between ACRped70 and genotypes were analyzed in a multivariate model and corrected for these 3 covariates: disease duration prior to MTX treatment, physician’s global assessment of disease activity at baseline, and MTX dose at all study visits.

Results.

MTX response was more often achieved by patients variant for the adenosine triphosphate-binding cassette transporter B1 (ABCB1) gene polymorphism rs1045642 (OR 3.80, 95% CI 1.70−8.47, p = 0.001) and patients variant for theABCC3gene polymorphism rs4793665 (OR 3.10, 95% CI 1.49−6.41, p = 0.002) than by patients with other genotypes. Patients variant for the solute carrier 19A1 (SLC19A1) gene polymorphism rs1051266 were less likely to respond to MTX (OR 0.25, 95% CI 0.09−0.72, p = 0.011).

Conclusion.

ABCB1rs1045642,ABCC3rs4793665, andSLC19A1rs1051266 polymorphisms were associated with response to MTX in 287 patients with JIA studied longitudinally. Upon validation of our results in other JIA cohorts, these genetic determinants may help to individualize treatment strategies by predicting clinical response to MTX.

A mindfulness-based group intervention to reduce psychological distress and fatigue in patients with inflammatory rheumatic joint diseases: a randomised controlled trial

OBJECTIVE

To evaluate the effects of a mindfulness-based group intervention, the Vitality Training Programme (VTP), in adults with inflammatory rheumatic joint diseases.

METHODS

In a randomised controlled trial, the VTP-a 10-session mindfulness-based group intervention including a booster session after 6 months-was compared with a control group that received routine care plus a CD for voluntary use with mindfulness-based home exercises. The primary outcome was psychological distress measured by the General Health Questionnaire-20. Self-efficacy (pain and symptoms) and emotion-focused coping (emotional processing and expression) were used as co-primary outcomes. Secondary outcomes included pain, fatigue, patient global disease activity, self-care ability and well-being. Effects were estimated by mixed models repeated measures post-intervention and at 12-month follow-up.

RESULTS

Of 73 participants randomised, 68 completed assessments post-intervention and 67 at 12 months. Significant treatment effects in favour of the VTP group were found post-treatment and maintained at 12 months in psychological distress (adjusted mean between-group difference -3.7, 95% CI -6.3 to -1.1), self-efficacy pain (9.1, 95% CI 3.4 to 14.8) and symptoms (13.1, 95% CI 6.7 to 19.3), emotional processing (0.3, 95% CI 0.02 to 0.5), fatigue (-1.1, 95% CI -1.8 to -0.4), self-care ability (1.0, 95% CI 0.5 to 1.6) and overall well-being (0.6, 95% CI 0.1 to 1.2). No significant group differences were found in emotional expression, pain or disease activity.

CONCLUSION

The VTP improved most primary and secondary outcomes compared with individual use of CD exercises. Improvements were maintained at 12 months, suggesting that the VTP is a beneficial complement to existing treatments for patients with inflammatory rheumatic joint diseases.

The association of luteinizing hormone and follicle-stimulating hormone with cytokines and markers of disease activity in rheumatoid arthritis: a case-control study

OBJECTIVES

Disease activity in rheumatoid arthritis (RA) varies substantially during periods when luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels change, for example during pregnancy, postpartum, and menopause. We wanted to investigate whether small fluctuations in these hormones could be associated with similar fluctuations in cytokines and disease activity in RA.

METHODS

Disease activity markers, serum LH, FSH, and 24 cytokines were assessed on days 1 and 8 in 20 RA patients (median age 58 years, six males) and 19 controls (median age 56 years, six males).

RESULTS

Percentage changes in LH and FSH correlated positively with percentage changes in key proinflammatory cytokines such as tumour necrosis factor (TNF)alpha (LH r = 0.737, p = 0.0007; FSH r = 0.680, p = 0.001) and interleukin (IL)-1beta (LH r = 0.515, p = 0.050; FSH r = 0.749, p = 0.0008). Similar correlations were observed with IL-2, IL-2R, IL-8, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and eotaxin, but not with the anti-inflammatory cytokine IL-10, in RA and not in controls. Percentage changes in LH, FSH, and cytokines were not correlated with percentage changes of several disease activity markers but were correlated positively with cross-sectional levels of disease activity markers [erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Visual Analogue Scale (VAS) pain, VAS global (physician/patient), and the modified Health Assessment Questionnaire (MHAQ)].

CONCLUSIONS

The significant associations between percentage changes in LH and FSH and percentage changes in key cytokines and several cross-sectional markers of disease activity may indicate that LH and FSH influence crucial points of the cytokine cascade in RA. This may help to explain, partially, why disease activity initiates or worsens during periods of increased LH and FSH, such as the postpartum period and the menopause.

Test-retest reliability of disease activity core set measures and indices in rheumatoid arthritis

AIM

To examine the test-retest reliability of the rheumatoid arthritis (RA) core disease activity measures and derived composite indices.

METHODS

A total of 28 stable patients with RA had 2 complete assessments within 1 week, which included the 7 RA core disease activity measures and derived disease activity indices (28-joint Disease Activity Score (DAS28), Simplified Disease Activity Index (SDAI), Clinical Disease Activity Index (CDAI), RA Disease Activity Index (RADAI) and Routine Assessment of Patient Index Data (RAPID3)). The intraclass correlations (ICC), the smallest detectable difference (SDD) and minimal detectable change as percentage of the maximum score (MDC%) were estimated as measures of test-retest reliability.

RESULTS

Correlations for the disease activity indices were high. SDDs (MDC%) to detect a true improvement or deterioration with 95% confidence were: DAS28 1.32 (14.4%), SDAI 8.26 (9.6%), CDAI 8.05 (10.6%), RAPID3 1.48 (14.8%) and RADAI 1.49 (14.9%). Thus, SDDs were rather high, and the MDC% values were of a similar magnitude of 10% to 15% for all seven core data set measures.

CONCLUSIONS

SDDs of the DAS28, SDAI and CDAI were close to limits to detect important improvement. Clinicians should be aware of measurement error. Nonetheless, RA core data set measures and indices obtained from a health professional, laboratory and patient self-report had similar reliability.