Study type | Number of CRsa) | Number of studies | Number of PMIDsb) |
---|---|---|---|
Randomized controlled trial | 183 | 1471 | 1598 |
Nonrandomized controlled trial | 67 | 216 | 331 |
Controlled before-after study | 104 | 634 | 556 |
Interrupted time series (with comparison group) | 31 | 83 | 106 |
Prospective cohort study | 84 | 384 | 435 |
Retrospective cohort study | 72 | 436 | 451 |
Non-concurrent cohort study | 13 | 34 | 31 |
(Nested) case-control study | 36 | 207 | 200 |
Cross-sectional study | 17 | 152 | 136 |
Non-comparative study (case report or case series) | 22 | 249 | 226 |
Before-after study | 41 | 257 | 239 |
Interrupted time series (without comparison group) | 45 | 221 | 179 |
Study type unclear | 42 | 138 | 56 |
Total | 271 | 4482 | 4544 (2890 on NRS) |