Table 1.

Numbers of participants involved in large-scale clinical trials to which questionnaires were sent, and number of participants involved in trials that responded

Number of participants in clinical trial	Responded trial* n (%)	Not-responded trial* n (%)	Total † n (%)
< 999	24 (38.1%)	28 (50.0%)	52 (43.7%)
1,000 - 2,999	19 (30.2%)	14 (25.0%)	33 (27.7%)
3,000 - 9,999	15 (23.8%)	7 (12.5%)	22 (18.5%)
≥ 10,000 -	3 (4.8%)	6 (10.7%)	9 (7.6%)
Unknown or no target number	2 (3.2%)	1 (1.8%)	3 (2.5%)
Total	63 (100%)	56 (100%)	119 (100%)

* Proportions (%) in all responding trials (63 trials) or all not-responded trials (56 trials) are shown.

† Proportions (%) in all trials (119 trials) are shown.