Effects of a Rehabilitation Program on Physical Performance and Disease Self-management in Rheumatoid Arthritis.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of a Rehabilitation Program on Physical Performance and Disease Self-management in Rheumatoid Arthritis. (NCT01307787), a randomized na study. The primary outcome is Change in VO2 Max, Maximum Oxygen Uptake in ml/Min/kg is the Standard Index of Cardio-respiratory Fitness.

2. Clinical Question

The clinical question concerns a short-term change in a measure of cardiorespiratory fitness, not long-term health outcomes or the separate effects of exercise and education. The intervention bundled those components in a group rehabilitation program, so the comparison evaluates the program as a whole against waiting-list control during the study period.

The registry also lists secondary questions about self-efficacy, muscle strength, health status, and social interaction. Those outcomes address other aspects of physical performance and disease self-management, but they are distinct from the primary VO2 max question. Their results should therefore be read as additional, less definitive evidence rather than substitutes for the primary outcome.

3. Trial Design

The study was randomized, used a parallel-group design, and was described as single-masked. The registry record does not identify who was masked. It lists the University Medical Center Groningen as sponsor, an enrollment of 34, and a completed status. The study start is recorded as 2005-04 and primary completion as 2007-05. The phase is listed as NA.

Participants were assigned to the Fit program or a waiting-list control group. The Fit program consisted of eight weeks of multidisciplinary group rehabilitation, with physical exercise and an educational component. The waiting-list group could enter the program after the study period. Thus, the randomized comparison was between immediate program participation and waiting for access until after the study period; it was not a comparison with an alternative active rehabilitation program.

The primary outcome was change in VO2 max, assessed at baseline and postintervention at 9 weeks. The registry describes this as a mean continuous measure with standard deviation. The primary-outcome summaries include 15 participants in the Fit program group and 13 in the waiting-list group. The registry states that VO2 max data were unavailable for 4 intervention participants and 2 waiting-list participants because of participant-specific testing conditions. It also says that 4 participants did not reach the heart rate needed to estimate VO2 max.

The registry record does not report the original sample-size justification, details of sequence generation or allocation concealment, or the identity of the person masked. These omissions limit how fully the design and conduct can be appraised from the registry record alone.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: A total of thirty-nine individuals were referred for this study. Thirty-four individuals returned a signed Informed Consent form and five decided not to participate for a variety of reasons.(Impairment due to trauma n = 1 Not able to follow the program n = 1 Personal reasons n = 3)

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Some VO2 max data (n=4 in the intervention group and n=2 in the WLC group)could not be collected because of specific participant conditions at different testing time points. 4 subjects did not reach the necessary heart rate to estimate the VO2 max. One subject had hypertension and one subject had knee problems.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Change in VO2 Max, Maximum Oxygen Uptake in ml/Min/kg is the Standard Index of Cardio-respiratory Fitness, measured over baseline, postintervention at 9 weeks.

VO2 max is the maximum oxygen uptake expressed in ml/min/kg. It is used as an index of cardiorespiratory fitness: a higher value represents greater measured oxygen uptake relative to body weight. The registry describes an Åstrand-Rhyming cycle-ergometer test. Workload increased by 25 watts each minute until a steady-state heart rate was reached; participants cycled for about 6 minutes, with heart rate recorded each minute. The mean heart rate from the 5th and 6th minute, the workload, and participant weight were used with the Åstrand-Rhyming nomogram to estimate maximal oxygen uptake.

The outcome is a continuous measure, and the registry reports group means and standard deviations for change from baseline to postintervention at 9 weeks. Continuous measures can retain information about the size of observed changes rather than reducing them to categories such as improved or not improved. That general advantage does not remove the need to consider measurement limitations, missing observations, and uncertainty around the group comparison.

The registry describes VO2 max as a standard index of cardiorespiratory fitness. It also notes that individual testing conditions prevented some measurements and that some participants did not reach the required heart rate. The measure therefore reflects an estimate obtained through a specific exercise test, not every dimension of physical performance or disease self-management.

7. Results Posted in the Registry

• Intervention Fit Program: mean 3.82 versus -0.44 on control; difference 4.26 (95% CI 1.97 to 6.55), standardized effect d = 1.33; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Self-efficacy Pain and Other Symptoms

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Fit Program: mean 0.42 versus 0.28 on control; difference 0.14 (95% CI -0.41 to 0.69), standardized effect d = 0.18; z-test p = 0.616.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Fit Program and the control. The interval gives the range of effects that remain compatible with the data.

Change in Self-efficacy Function

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Fitprogram Group: mean 0.29 versus 0.10 on control; difference 0.19 (95% CI -0.14 to 0.52), standardized effect d = 0.39; z-test p = 0.262.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Fitprogram Group and the control. The interval gives the range of effects that remain compatible with the data.

Change in Muscle Strength of the Upper Extremity

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intervention Fitprogram Group: mean 36.06 versus -5.49 on control; difference 41.55 (95% CI -32.91 to 116.01), standardized effect d = 0.37; z-test p = 0.274.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intervention Fitprogram Group and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary outcomes spanning self-efficacy for pain and other symptoms, self-efficacy for function, upper- and lower-extremity muscle strength, physical and psychological health status, and social interaction. The numerical comparisons included for some of these outcomes show a mixed pattern rather than a consistent, clearly separated signal across domains. The other listed domains should not be assigned a result based on the findings for outcomes with numerical comparisons.

For the numerical secondary comparisons, the mean-based estimates are positive, but their confidence intervals include zero and their unadjusted p-values do not show strong evidence of a group difference. The registry's reported Wilcoxon p-values for those comparisons also vary. These secondary results are less definitive than the primary comparison, both because they address additional questions and because multiple outcomes create more opportunities for chance findings.

The primary outcome concerns VO2 max, while the secondary outcomes capture different measures of function and self-management. A result for cardiorespiratory fitness does not imply a corresponding change in self-efficacy, strength, health status, or social interaction. Likewise, uncertain secondary findings do not negate the primary comparison; they indicate that conclusions should remain outcome-specific.

The registry record does not report a multiplicity adjustment or a prespecified hierarchy for secondary outcomes. In the absence of such information, unadjusted secondary p-values should be treated as exploratory rather than as a set of independent confirmatory tests. Repetition of a pattern across well-planned studies would be more informative than selecting isolated nominal findings from many outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Self-efficacy Pain and Other Symptoms
• Change in Self-efficacy Function
• Change in Muscle Strength of the Upper Extremity
• Change in Muscle Strength of the Lower Extremity
• Change in Health Status: Physical Health
• Change in Health Status: Psychological Health
• Change in Health Status: Social Interaction

9. Statistical Interpretation

10. Statistical Methods Explained

The registry characterizes the primary outcome as a continuous measure summarized by means and standard deviations. A mean describes the average observed change within a group. A standard deviation describes variation among individual observations around that group mean; it is not the same as the uncertainty in the mean or in a comparison between groups.

What does the mean difference describe?

The unadjusted mean difference is the intervention-group mean change minus the control-group mean change. For the primary outcome, the recalculated estimate is 4.26 ml/min/kg. It describes the difference between the two reported average changes; it is not the change experienced by every participant. Individual responses can vary around the group averages.

A simple comparison based on summary means is useful for expressing the size of the contrast in the outcome's original units. It does not adjust for baseline values, other participant characteristics, or missing observations. The registry record does not report an adjusted model for the primary outcome, so no adjustment should be presumed.

Why are there two p-values?

The registry reports a Wilcoxon (Mann-Whitney) test for the primary comparison. This rank-based method compares the ordering of observations between groups and does not rely on the same calculation as a test of the difference between means. The recalculated p-value is based on the posted summary statistics and is an unadjusted mean-based calculation. Different methods can yield different p-values because they use the data in different ways and may address different aspects of the group distributions.

A p-value describes how compatible observed data are with a specified null model, assuming the analysis assumptions hold. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The registry record does not report the full statistical analysis plan, so the intended role of each analysis, any prespecified hierarchy, and any adjustment strategy cannot be established from the record.

What does a confidence interval add?

A confidence interval expresses uncertainty around an estimated contrast. In repeated use of a method under its assumptions, intervals constructed in that way would cover the underlying parameter at the stated rate. For an individual result, the interval gives a range of values compatible with the data and method; it does not guarantee that the true value lies in the interval. The recalculated primary interval, from 1.967 to 6.553 ml/min/kg, is above zero. Its width also conveys that the estimate is not exact.

The interval is tied to the mean-based recalculation, rather than the reported Wilcoxon analysis. The registry does not provide a confidence interval for its rank-based result. This distinction matters: an interval for a mean difference should not be presented as if it were an interval produced by the registry's reported test.

Why can small samples be difficult to interpret?

With relatively few observations, a small number of participants can have a substantial influence on group summaries. Estimates can also be imprecise, and the ability of a study to distinguish a real effect from random variation may be limited, especially for modest differences. A non-significant result does not establish that groups are equivalent or that no difference exists. Conversely, a small p-value does not by itself establish that an estimated difference is important to patients.

For continuous outcomes, marked variation or outliers can affect means and standard deviations. Rank-based analyses can be useful when the assumptions of a mean-based approach are questionable, but a rank test does not automatically answer the same question as a difference in means. The registry record does not report distributional checks, diagnostic plots, or the rationale for selecting the Wilcoxon method.

Why does over-dispersion matter in general?

General statistical explanation: over-dispersion means that observed variability is greater than a model assumes. When a method underestimates variation, uncertainty intervals can be too narrow and tests can appear more decisive than warranted. This concept is especially relevant to count or binary outcomes modeled with assumptions about variability. The primary endpoint in this study is continuous, and the registry does not report an over-dispersion model; it should not be assumed that over-dispersion was assessed or was present.

More broadly, the analysis should be read in light of randomization, the number with outcome measurements, the testing-related missing data, and the difference between the registry's rank-based result and the unadjusted mean-based recalculation. The registry record does not report interim analyses, a detailed analysis plan, or a sample-size justification. Their presence or absence in the conduct of the study cannot be inferred from that lack of reporting.

11. Confidence Intervals and Precision

The primary mean difference recalculated from the posted summaries is 4.26 ml/min/kg, with a 95% confidence interval from 1.967 to 6.553. The interval lies above zero, so the recalculated mean-based comparison is compatible with a positive average difference. Its endpoints also show that the data do not identify the mean difference with pinpoint precision. The estimate should be understood as a range of plausible values under the calculation's assumptions, rather than as an exact quantity.

Confidence intervals are general tools for communicating estimation uncertainty. A narrower interval indicates greater precision for the parameter and method used; a wider interval indicates less precision. Precision depends on factors such as the amount of information, variability, and the analysis method. Here, the primary comparison is based on 15 intervention participants and 13 waiting-list participants with reported VO2 max changes. The registry also reports missing VO2 max data for 4 and 2 participants, respectively, because of testing conditions.

The confidence interval is from a simple unadjusted recalculation of the mean difference. It is not reported as the interval from the registry's Wilcoxon analysis, for which the registry gives p = 0.002 but no interval estimate. The registry's analysis and the mean-based interval therefore answer related but not identical statistical questions.

For the secondary endpoints with numerical comparisons, intervals that include zero indicate that the posted summaries do not rule out no mean difference under the corresponding recalculation. Such intervals may also be compatible with differences in either direction. They should not be read as proof of equivalence. The sample sizes, variability, and number of outcomes considered all affect how much can be concluded from these estimates.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size estimates are planning illustrations based on observed effects, not the trial's original design calculations. For this continuous-outcome setting, the figures are participants per arm, not total events. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect equal to the listed fraction of the observed effect. The original trial's sample-size assumptions and justification are not reported in the registry record.

The 80% power column means the illustrative number of participants per arm that would give an 80% chance of detecting the assumed effect under those planning assumptions, if that effect and the model assumptions were correct. The 90% power column uses a higher target chance of detection. These are design-planning targets, not probabilities that the observed result is correct and not measures of the study's observed power.

The rows consider planning for 100%, 75%, and 50% of the observed effect. The smaller the effect targeted for detection, the more participants are generally needed to distinguish it from random variation while maintaining the same significance and power targets. This pattern is a general feature of planning calculations, not evidence that the smaller effect is the true one.

Because the observed effect comes from a small study, it may be an unstable basis for future planning. These calculations also rely on the listed approximation and assumptions, which may not capture all design features or missing-data issues. The registry record does not report the trial's original sample-size justification, and these illustrative estimates should not be mistaken for that original rationale.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 4.260; pooled standard deviation σ = 3.206.
2. n = 2 × (1.96 + 0.842)² × 3.206² / 4.260² = 8.9, rounded up to 9 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 4.26                      # observed difference in means
sigma <- 3.20578563513868                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1307787)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 9 (80% power), 12 (90% power)
 75% of observed effect: n per arm = 16 (80% power), 22 (90% power)
 50% of observed effect: n per arm = 36 (80% power), 48 (90% power)
power.t.test: 9.9 
Simulated power at n = 9 per arm: 0.749 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The registry's own primary analysis is a Wilcoxon (Mann-Whitney) comparison, with p = 0.002. It does not report a parameter estimate or confidence interval for that analysis. The separate recalculation uses the posted means, standard deviations, and sample sizes to estimate an unadjusted mean difference of 4.26 ml/min/kg, with a 95% confidence interval from 1.967 to 6.553 and p < 0.001.

These results are related but not interchangeable. A rank-based test evaluates group differences using the ordering of observations, while the recalculation summarizes the contrast in group means. The resulting p-values need not match, and the mean-based interval does not supply an interval for the Wilcoxon analysis. The registry's test is the reported trial analysis; the recalculation is a supplementary summary-based analysis, not a replacement for it.

The registry record does not give the Wilcoxon test's detailed assumptions, the analysis population, or an adjusted effect estimate. It also does not identify whether the rank-based analysis was prespecified. Those details are not reported in the registry record, so the relationship between the reported analysis and any original analysis plan cannot be determined.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and several secondary outcomes, but a statistical plan describing how these outcomes were prioritized or analyzed is not reported in the registry record. It does not report whether the primary outcome was selected before examining the results, whether secondary hypotheses were prespecified, or whether multiplicity was addressed. Without that information, the reported p-values cannot be placed in a fully documented testing hierarchy.

Multiplicity matters because evaluating many outcomes can increase the chance that at least one result appears noteworthy by chance. Adjustments can control that risk, but they may also affect the interpretation and precision of individual tests. The registry record does not say that an adjustment was used, so the secondary p-values should be read as unadjusted reported comparisons rather than as multiplicity-controlled evidence.

Missing primary-outcome data are explicitly noted: VO2 max could not be collected for 4 participants in the intervention group and 2 in the waiting-list group. The record describes participant-specific testing conditions and says that some participants did not reach the necessary heart rate. It does not report whether missingness differed in a way related to potential outcome values, whether any imputation was done, or how missing observations were handled in the primary analysis.

The record also does not report the analysis population definition, such as whether all randomized participants were included in the primary analysis, or whether any per-protocol analysis was conducted. It does not provide participant flow details sufficient to reconstruct all exclusions and outcome availability across the study. Therefore, the group summaries should be interpreted as summaries of the participants for whom outcomes are reported, without assuming an unreported missing-data method or analysis population.

Interim analyses, stopping rules, and a full statistical analysis plan are also not reported in the registry record. No conclusion about whether these procedures were used can be drawn from their non-reporting.

16. What the Result Does, and Does Not, Mean

The posted primary outcome data show a larger average increase in VO2 max in the Fit program group than in the waiting-list control group during the assessed period. The recalculated unadjusted difference is 4.26 ml/min/kg, and its 95% confidence interval is above zero. The registry's reported Wilcoxon analysis gives p = 0.002. These findings describe the comparison in the reported outcome data; they do not settle every question about the program or the people who participated.

The result does not establish that each participant experienced an increase, that the observed difference persisted beyond the postintervention assessment, or that the intervention changed outcomes not measured by VO2 max. The study compared a combined exercise and education program with waiting-list control, so it cannot separate the effect of each component. It also does not compare the program with another active treatment or rehabilitation approach.

The primary-outcome measurements were unavailable for some participants because of testing conditions. The registry record does not report the analysis population or how missing outcomes were handled, which limits interpretation of how representative the group summaries are of all randomized participants. The study's enrollment was 34, while the primary summaries report measurements for 15 participants in the intervention group and 13 in the waiting-list group.

A statistically notable comparison is not, by itself, a measure of clinical importance. The registry does not report a threshold for a clinically important change in VO2 max, and no such threshold should be inferred from the p-value or confidence interval. The findings also do not establish effects on disease activity, safety beyond the information recorded, or long-term outcomes.

Overall, the result supports a short-term between-group difference in the reported fitness measure, with uncertainty and missing-data limitations that should remain part of its interpretation. It is not a basis for medical advice or a general conclusion about all people with rheumatoid arthritis.

17. Why This Trial Matters Statistically

Statistically, this trial illustrates why an estimated effect, its uncertainty, and the method used to test a comparison should be considered together. The mean-based recalculation expresses the primary contrast in the original VO2 max units, while the registry reports a rank-based test. Both concern the same randomized groups, but they do not produce identical statistical summaries or answer precisely the same question.

The study also highlights the importance of outcome availability. VO2 max requires a participant to complete a test that reaches the conditions needed for estimation. The registry reports that testing conditions prevented collection for some participants and that some did not reach the necessary heart rate. Missingness tied to a measurement process is relevant to interpretation even when the observed group results appear clear.

Multiple outcomes can broaden the clinical picture, but they also raise statistical questions about prespecification and multiplicity. The registry lists outcomes across several domains, while the original hierarchy and any adjustment strategy are not reported. This makes it especially important to distinguish the primary result from secondary findings and to avoid treating every unadjusted comparison as confirmatory.

Finally, planning calculations based on the observed effect can help readers understand how sample size relates to a target effect, power, and uncertainty. They do not reconstruct the trial's original design rationale. The registry record's lack of a reported original sample-size justification underscores the value of transparent reporting of design assumptions and analysis plans.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary-outcome sample is limited: the reported summaries include 15 participants in the Fit program group and 13 in the waiting-list control group, while the registry records an enrollment of 34. VO2 max data were unavailable for 4 intervention participants and 2 waiting-list participants. The reason is described in terms of participant-specific testing conditions, including not reaching the required heart rate. The registry record does not explain how these missing values were handled in the analysis.

The outcome was measured at baseline and postintervention at 9 weeks, so the posted primary result addresses short-term change only. Longer-term follow-up is not reported in the outcome description. The intervention combined exercise and education; the design as described does not disentangle their separate contributions.

The waiting-list group was allowed to enter the FIT program after the study period. This is relevant to the design and the timing of the comparison, but the record does not provide later outcome results for that access. The registry describes the study as single-masked without specifying who was masked. Details of random sequence generation, allocation concealment, protocol deviations, and analysis populations are not reported in the registry record.

The numerical information includes mean changes and standard deviations, but does not provide participant-level data or a confidence interval from the reported Wilcoxon test. The primary mean-based interval is a recalculation rather than the registry's own interval estimate. The original sample-size justification, full statistical analysis plan, and any multiplicity strategy are not reported.

The adverse-event record lists zero participants at risk and zero affected for serious and other adverse events in each group; deaths are not specified with a numeric count. These fields do not provide enough context to characterize safety outcomes or infer that no events occurred. The registry information should therefore be read as limited outcome reporting, not as a comprehensive safety assessment.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Effects of a Rehabilitation Program on Physical Performance and Disease Self-management in Rheumatoid Arthritis. — NCT01307787.
• Registry record last updated 2022-01-28; status last verified 2022-01.
• Results first posted 2011-05-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

NCT01307787 is a completed, randomized, parallel-group study of a multidisciplinary group rehabilitation program for people with rheumatoid arthritis. The program combined physical exercise and education over eight weeks; the comparator was a waiting-list control group that could enter the program after the study period. The registry lists an enrollment of 34 and describes the study as single-masked, without identifying who was masked.

The primary outcome was change in VO2 max from baseline to postintervention at 9 weeks. Reported mean changes were 3.82 ml/min/kg for the intervention group and -0.44 ml/min/kg for the control group. The registry reports a Wilcoxon (Mann-Whitney) p-value of 0.002. A separate unadjusted recalculation gives a mean difference of 4.26 ml/min/kg, with a 95% confidence interval from 1.967 to 6.553.

Some VO2 max data were unavailable because of testing conditions. The registry lists secondary outcomes in self-efficacy, strength, health status, and social interaction domains. The original sample-size justification, analysis population, missing-data method, and multiplicity strategy are not reported in the registry record.