Table 1 Characteristics of six studies reviewing subgroup analyses in randomized trials
Study ID | Trial area | Source of study | Number of trials | Trial feature for eligibility criteria |
|---|---|---|---|---|
Wang (2007) | Multiple | NEJM (July 2005 to June 2006) | 97 (59 reporting subgroup analyses) | No restrictions |
Bhandari (2006) | Surgical | Two surgical journals plus NEJM, JAMA, BMJ, and Lancet (Jan 2000 to Apr 2003) | 72 (27 reporting subgroup analyses) | No restriction on size and other trial characteristics |
Hernandez (2006) | Cardiovascular | Four cardiovascular journals plus "Top Five" (2002 and 2004) | 63 (39 reporting subgroup analyses) | Phase 3 parallel trials, n ≥ 100, superiority trials; restricted to main reports |
Hernandez (2005) | Traumatic brain | MEDLINE (1966 to Apr 2004), EMBASE (1978 to Apr 2004), CENTRAL (Apr 2004) | 18 (11 reporting subgroup analyses) | Phase 3, parallel trials, n ≥ 50 per arm Glasgow Outcome Scale (GOS) at 3 months as outcome |
Moreira Jr (2001) | Multiple | NEJM, JAMA, Lancet, American Journal of Public Health (July 1998) | 32 (17 reporting subgroup analyses) | No restrictions mentioned. |
Assmann (2000) | Multiple | NEJM, JAMA, BMJ, and Lancet (July to Sep 1997) | 50 (35 reporting subgroup analyses) | No crossover and cluster trials, n ≥ 50 |