Incentive n = 1070 (%) | No incentive n = 1074 (%) | Risk ratio | |
---|---|---|---|
Questionnaire returned | 810 (75.7) | 738 (68.7) | 1.10 (1.05, 1.16) |
Questionnaire returned without chasing | 560 (52.3) | 493 (45.9) | 1.14 (1.05, 1.24) |
Non-responder (after all follow-up efforts including outcome data collection by telephone) | 96 (9.0) | 142 (13.2) | 0.68 (0.53, 0.87) |