Disclosure of information to potential subjects on research recruitment web sites.

Any incentivec 125 (73.1%) N/A N/A 138 (75.0%) N/A N/A NS Any financial incentive 93 (54.4%) N/A N/A 84 (45.7%) N/A N/A 0.062 Specific amount of incentive 21 (12.3%) 21 (22.6%) N/A 36 (19.6%) 36 (42.9%) N/A 0.042 Nonmonetary incentive (e.g., free medication, treatment, evaluation) 81 (47.4%) 49 (52.7%) 0.086 114 (62.0%) 55 (65.5%) NS 0.004 Number of visits 58 (33.9%) 35 (37.6%) NS 33 (17.9%) 22 (26.2%) 0.006 0.000 Study length 74 (43.3%) 46 (49.5%) 0.051 69 (37.5%) 30 (35.7%) NS NS Any procedure that appears more than minimal risk (includes administration of drug or device and/or assessment—e.g., LP) 115 (67.3%) 58 (62.4%) 0.093 142 (77.2%) 57 (67.9%) 0.005 0.024 Intervention that appears more than minimal risk (e.g., administration of active drug or device) 115 (67.3%) 58 (62.4%) 0.093 140 (76.1%) 55 (65.6%) 0.002 0.042 Additional procedures that appear more than minimal riskd, e 4 (2.3%) 1 (1.1%) 2 (1.1%) 2 (2.4%) Clinical trial 107 (62.6%) 55 (59.1%) NS 124 (67.4%) 54 (64.3%) NS NS Source of funding listedf 4 (2.3%) 2 (2.2%) N/A 25 (13.6%) 12 (14.3%) N/A N/A Type of funding, if listed For-profit 1 (0.6%) 0 (0.0%) N/A 0 (0.0%) 0 (0.0%) N/A N/A Not-for-profit 3 (1.8%) 2 (2.2%) N/A 25 (13.6%) 12 (14.3%) N/A N/A Unlisted 167 (97.7%) 91 (97.8%) N/A 159 (86.4%) 72 (85.7%) N/A N/A Type of institutional affiliation of contactf NS NS 0.008 For-profit 82 (48.0%) 45 (48.4%) N/A 70 (38.0%) 34 (40.5%) N/A N/A Not-for-profit 75 (43.9%) 44 (47.3%) N/A 111 (60.3%) 49 (58.3%) N/A N/A Unlisted 14 (8.2%) 4 (4.3%) N/A 3 (1.6%) 1 (1.2%) N/A N/A a. P-values represent results of a Fisher’s Exact Test comparing rates of mention of incentive with rates of mention of other study characteristics. b. P-values represent results of a Fisher’s Exact Test comparing rates of mention of various study characteristics between disease categories. c. Incentives include financial compensation, free medical treatment, free medicine, and other nonmonetary incentives. d. For example, lumbar puncture, but not administration of a medication or device. e. Chi square statistics were not computed, since sample sizes were too small. f. In statistical analyses, we excluded those sites whose type of institutional afiliation of contact was unlisted.