Effects of exercise on depression in adults with arthritis: a systematic review with meta-analysis of randomized controlled trials

Abstract

Introduction: Previous randomized controlled trials have led to conflicting findings regarding the effects of exercise on depressive symptoms in adults with arthritis and other rheumatic conditions (AORC). The purpose of this study was to use the meta-analytic approach to resolve these discrepancies.

Methods: The inclusion criteria were: (1) randomized controlled trials, (2) exercise (aerobic, strength training, or both) ≥4 weeks, (3) comparative control group, (4) adults with osteoarthritis, rheumatoid arthritis, fibromyalgia or systemic lupus erythematosus, (5) published studies in any language since January 1, 1981 and (6) depressive symptoms assessed. Studies were located by searching 10 electronic databases, cross-referencing, hand searching and expert review. Dual-selection of studies and data abstraction was performed. Hedge's standardized mean difference effect size (g) was calculated for each result and pooled using random-effects models, an approach that accounts for heterogeneity. Non-overlapping 95% confidence intervals (CI) were considered statistically significant. Heterogeneity based on fixed-effect models was estimated using Q and I (2) with alpha values ≤0.10 for Q considered statistically significant.

Results: Of the 500 citations reviewed, 2,449 participants (1,470 exercise, 979 control) nested within 29 studies were included. Length of training, reported as mean ± standard deviation (±SD) was 19 ± 16 weeks, frequency 4 ± 2 times per week and duration 34 ± 17 minutes per session. Overall, statistically significant exercise minus control group reductions were found for depressive symptoms (g = -0.42, 95% CI, -0.58, -0.26, Q = 126.9, P <0.0001, I(2) = 73.2%). The number needed-to-treat was 7 (95% CI, 6 to 11) with an estimated 3.1 million (95% CI, 2.0 to 3.7) United States adults not currently meeting physical activity guidelines improving their depressive symptoms if they began and maintained a regular exercise program. Using Cohen's U3 Index, the percentile reduction was 16.4% (95% CI, 10.4% to 21.9%). All studies were considered to be at high risk of bias with respect to blinding of participants and personnel to group assignment.

Conclusions: Exercise is associated with reductions in depressive symptoms among selected adults with AORC. A need exists for additional, well-designed and reported studies on this topic.

Figure 1

Flow diagram for the selection of studies. *, number of reasons exceeds the number of studies because some studies were excluded for more than one reason.

Figure 2

Risk of bias. Pooled risk of bias results using the Cochrane Risk of Bias Assessment Instrument.

Figure 3

Forest plot for changes in depressive symptoms. Forest plot for point estimate changes in depressive symptoms. The black squares represent the mean difference while the left and right extremes of the squares represent the corresponding 95% confidence intervals. The middle of the black diamond represents the overall mean difference while the left and right extremes of the diamond represent the corresponding 95% confidence intervals. Combined measures represent those studies in which multiple assessment instruments for depression and/or per-protocol and intention-to-treat analyses were merged.

Figure 4

Funnel plot for changes in depressive symptoms. Small-study effects are apparently present given the lack of results in the lower right section of the funnel plot.

Figure 5

Influence analysis for changes in depressive symptoms. Influence analysis for point estimate changes in depressive symptoms with each corresponding study deleted from the model once. The black squares represent the mean difference while the left and right extremes of the squares represent the corresponding 95% confidence intervals. The middle of the black diamond represents the overall mean difference while the left and right extremes of the diamond represent the corresponding 95% confidence intervals. Results are ordered from smallest to largest reductions. Combined measures represent those studies in which multiple assessment instruments for depression and/or per-protocol and intention-to-treat analyses were merged.

Figure 6

Cumulative meta-analysis for changes in depressive symptoms. Cumulative meta-analysis, ordered by year, for point estimate changes in depressive symptoms. The black squares represent the mean difference while the left and right extremes of the squares represent the corresponding 95% confidence intervals. The results of each corresponding study are pooled with all studies preceding it. The middle of the black diamond represents the overall mean difference while the left and right extremes of the diamond represent the corresponding 95% confidence intervals. Combined measures represent those studies in which multiple assessment instruments for depression and/or per-protocol and intention-to-treat analyses were merged.