Summary of Intervention Intensity- and Duration-Stratified Analysis
| Intervention Intensity and Duration | Number of Trials | Relative Risk (95% CI) |
|---|---|---|
| Low intensity | ||
| ≤6 months39,44,53,56 | 5 | 1.121 (0.97–1.30) |
| >6 months40–42,57,62,70 | 7 | 0.949 (0.86–1.10) |
| Moderate intensity | ||
| ≤6 months45–47,54,59,64,66,71,72 | 10 | 0.981 (0.86–1.30) |
| >6 months58,60,63 | 4 | 0.788 (0.70–0.90) |
| High intensity | ||
| ≤6 months10,48–52,55,73 | 9 | 0.804 (0.69–0.93) |
| >6 months58,61,65,67–69 | 7 | 0.885 (0.79–0.99) |
Note: Test for differences across 6 strata: P = .003