Table 3.
Details of forest plots and subgroup analysis and frequency of reporting of subgroup analysis in the different sections of the publication and according to impact factor
| Trials with subgroup analysis (n = 217) | Low IF | Intermediate IF | High IF | P value | |
|---|---|---|---|---|---|
| Forest plot for the primary endpoint | 195/217 (89.9%) | 28/40 (70.0%) | 102/111 (91.9%) | 65/66 (98.5%) | P < 0.001 |
| In the main article | 158/195 (81.0%) | 23/28 (82.1%) | 84/102 (82.4%) | 51/65 (78.5%) | |
| In the supplementary material only | 37/195 (19.0%) | 5/28 (17.9%) | 18/102 (17.6%) | 14/65 (21.5%) | |
| Forest plot for the secondary endpoint | 58/217 (26.7%) | 13/40 (32.5%) | 30/111 (27.0%) | 15/66 (22.7%) | P = 0.27 |
| In the main article | 36/58 (62.1%) | 10/13 (76.9%) | 18/30 (60.0%) | 8/15 (53.3%) | |
| In the supplementary material only | 22/58 (38.9%) | 3/13 (23.1%) | 12/30 (40.0%) | 7/15 (46.7%) | |
| Number of variables | |||||
| Primary endpoint: median (range) | 9 (3-19) | 7 (3-14) | 9 (3-19) | 9 (4-19) | P = 0.19 |
| Secondary endpoint: median (range) | 8.5 (1-19) | 8 (1-14) | 8.50 (3-19) | 9 (1-19) | P = 0.98 |
| Number of subgroups | |||||
| Primary endpoint: median (range) | 19 (6-78) | 15.5 (6-30) | 20 (6-78) | 19 (8-38) | P = 0.21 |
| Secondary endpoint: median (range) | 20 (2-43) | 20 (2-29) | 20 (6-43) | 21 (2-31) | P = 0.79 |
| Test for interaction | |||||
| Primary endpoint, all trials | 60/217 (27.6%) | 9/40 (22.5%) | 43/111 (38.7%) | 8/66 (12.1%) | P = 0.07 |
| Primary endpoint, only trials with forest plot | 52/195 (26.7%) | 6/28 (21.4%) | 39/102 (38.2%) | 7/65 (10.8%) | P = 0.03 |
| Secondary endpoint, all trials | 21/217 (9.7%) | 3/40 (7.5%) | 14/111 (12.6%) | 4/66 (6.1%) | P = 0.61 |
| Secondary endpoint, only trials with forest plot | 17/58 (29.3%) | 3/13 (23.1%) | 12/30 (40.0%) | 2/15 (13.3%) | P = 0.51 |
| Pvalue for each subgroup | |||||
| Primary endpoint, all trials | 36/217 (16.6%) | 12/40 (30.0%) | 20/111 (18.0%) | 4/66 (6.1%) | P = 0.001 |
| Primary endpoint, only trials with forest plot | 29/195 (14.9%) | 8/28 (28.6%) | 17/102 (16.7%) | 4/65 (6.2%) | P = 0.004 |
| Secondary endpoint, all trials | 14/217 (6.5%) | 4/40 (10.0%) | 7/111 (6.3%) | 3/66 (4.5%) | P = 0.28 |
| Secondary endpoint, only trials with forest plot | 6/58 (10.3%) | 1/13 (7.7%) | 3/30 (10.0%) | 2/15 (13.3%) | P = 0.62 |
| Reporting of subgroup analysis in the different sections of the publications | |||||
| Abstract | 41/217 (18.9%) | 11/40 (27.5%) | 17/111 (15.3%) | 13/66 (19.7%) | P = 0.46 |
| Results | 205/217 (94.5%) | 39/40 (97.5%) | 106/111 (95.5%) | 60/66 (90.9%) | P = 0.13 |
| Discussion/conclusions | 174/217 (80.2%) | 34/40 (85.0%) | 88/111 (79.3%) | 52/66 (78.8%) | P = 0.48 |
Bold values correspond to a P value with statistically significant results.
IF, impact factor.