Table 1.

Participation rates.

	Study 1	Study 2
Total eligible index cases (n)	247	67
Lost to follow-up	78 (31.6%)	11 (16.4%)
Declined to participate	44 (17.8%)	17 (25.3%)
No response	35 (14.2%)	22 (32.8%)
Index cases (n)	90	17
Participating parents completed	126	28
Participation rate (by index case)a	90/169 = 53.3%	17/56 = 30.4%

^a“Participation rate” = “index cases”/(“total eligible” − “lost to follow-up”).