TABLE 2

Characteristics of Completed and Discontinued RCTs

All Trials (n = 559), n (%)Completed Trials (n = 455), n (%)Discontinued Trials (n = 104), n (%)P
Intervention.81
 Behavioral55 (9.8)47 (10)8 (7.7)
 Drug/Biologic379 (67.8)304 (66.8)75 (72.1)
 Device/Procedure37 (6.6)32 (7.0)5 (4.8)
 Dietary supplement45 (8.1)37 (8.1)8 (7.7)
 Other43 (7.7)35 (7.7)8 (7.7)
Age of study participants.60
 Preterm, newborn, and infant145 (25.9)119 (26.2)26 (25.0)
 Toddler and preschool119 (21.3)101 (22.2)18 (17.3)
 School age68 (12.2)57 (12.5)11 (10.6)
 Adolescent60 (10.7)46 (10.1)14 (13.5)
 Mixed ages167 (29.9)132 (29.0)35 (33.7)
Primary funding source.044
 Academic institution245 (43.8)188 (41.3)57 (54.8)
 Industry272 (48.7)231 (50.8)41 (39.4)
 Other42 (7.5)36 (7.9)6 (5.8)
Year registered.84
 2008199 (35.6)161 (35.4)38 (36.5)
 2009202 (36.1)163 (35.8)39 (37.5)
 2010158 (28.3)131 (28.8)27 (26.0)
Trial phasea.16
 Phase 129 (5.2)26 (5.7)3 (2.9)
 Phase 2115 (20.6)89 (19.6)26 (25.0)
 Phase 3186 (33.3)159 (35.0)27 (26.0)
 Phase 481 (14.5)61 (13.4)20 (19.2)
 Unknown148 (26.5)120 (26.4)28 (26.9)
Masking.22
 Open label187 (33.5)155 (34.1)32 (30.8)
 Single blind77 (13.8)67 (14.7)10 (9.6)
 Double bind295 (52.8)233 (51.2)62 (59.6)
Planned sample size<.001
 <100 participants212 (37.9)161 (35.4)51 (49.0)
 100–499 participants227 (40.6)182 (40.0)45 (43.3)
 >500 participants120 (21.5)112 (24.6)8 (7.7)
  • a Phase 0 trials (n = 5) included as phase 1. Trials described as phase 1/2 (n = 17) were categorized as phase 2, and trials described as phase 2/3 (n = 18) were categorized as phase 3.