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Table 3 Eligibility criteria and searches (the HTA data were collected for this study; all other data are from Page et al. [1], i.e. the data collected for 300 systematic reviews for a single month in 2004 and 2014)

From: Nature and reporting characteristics of UK health technology assessment systematic reviews

Characteristic 2004 n = 300 [1] HTA 2004 n = 23 HTA 2014 n = 30 Cochrane 2014 n = 45 [1] 2014 n = 300 [1]
Type of included literature
Published and unpublisheda - (41%) 9/23 (39%) 19 (65%) 41 (91%) 116 (39%)
Published only - (23%) 0 1 (5%) 2 (4%) 80 (27%)
Not reported - (36%) 14/23 (61%) 10 (33%) 2 (4%) 103 (34%)
All languages - (37%) 11 (48%) 18 (60%) 37 (82%) 129 (43%)
English only - (16%) 9 (39%) 11 (37%) 1 (2%) 92 (31%)
Not reported - (45%) 3 (13%) 1 (3%) 6 (13%) 48 (16%)
Study design criteria specifiedb - (72%) 21/23 (93%) 30/30 (100%) 45 (100%) 237 (79%)
RCTs NR 15 (65%) 25 (83%) 44 (98%) 158 (53%)
Quasi-RCTs NR 3 (13%) 11 (37%) 14 (31%) 33 (11%)
Controlled NR 3 (13%) 12 (40%) 4 (9%) 30 (10%)
Cohort NR 1 (4%) 12 (40%) 0 (0%) 76 (25%)
Case-control NR 0 (0%) 4 (13%) 0 (0%) 49 (16%)
Other NR 5 (22%) 4 (13%) 1 (2%) 56 (19%)
Unclear NR 2 (9%) 2 (6%) 0 (0%) 36 (12%)
Only RCTs / Quasi-RCTs NR 9 (39%) 8 (27%) 40 (89%) 107 (36%)
Number of databases median (range) 3 10 (4–15) 9 (2–13) 5 (4–6) 4 (3–5)
Start / end dates of all databases given - (69%) 20/23 (87%) 28 (93%) 41 (91%) 196 (65%)
Only some start / end dates given - (16%) 1/23 (4%) 2 (7%) 4 (9%) 88 (29%)
Full search given of ≥ 1 database - (42%) 21/23 (91%) 30 (100%) 44 (98%) 134 (45%)
Other sources searched
One or more trial registriesa NR 12 (52%) 21 (70%) 28 (62%) 58 (19%)
Number of other source types searched NR 3 (1–6) 3 (1–6) 2 (1–3) 1 (1–2)
Grey literature NR 8 (35%) 15 (50%) 9 (20%) 21 (7%)
Reference lists NR 21 (91%) 26 (87%) 38 (84%) 243 (81%)
Conference abstracts NR 7 (30%) 10 (33%) 11 (24%) 47 (16%)
Experts NR 7 (30%) 16 (53%) 23 (51%) 54 (18%)
Handsearching particular journals NR 5 (22%) 3 (10%) 6 (13%) 25 (8%)
Manufacturers NR 14 (61%) 4 (13%) 8 (18%) 11 (4%)
Regulators NR 3 (13%) 0 (0%) 0 (0%) 2 (1%)
Citation tracking NR 2 (9%) 2 (7%) 8 (18%) 35 (12%)
  1. HTA Health Technology Assessment; aNote: there are some inconsistencies in the data because a search for ‘unpublished’ data might not be noted explicitly in the Methods of a Health Technology Assessment systematic review, but trial registers and grey literature are searched and often included and have much higher percentages bSome of the figures do not add-up to 100% because, for example in study designs, a systematic review might include more than one design; NR Not reported