Table 1. Methodological characteristics of 425 studies measuring ICU survivor outcomes (1970 - 2013).

	Cross-sectional studies*	Cohort studies with 1 follow-up assessment*	Cohort studies with >1 follow-up assessment*	Randomized Controlled Trials
	N=116 (27%)	N=168 (39%)	N=110 (26%)	N=31 (7%)
Months from discharge to last assessment: median (IQR)†	31 (18 - 52)	6 (6 - 12)	12 (12 - 12)	12 (5 - 12)
No. follow-up assessments: median (IQR)			2 (2 - 3)	1 (1 - 2)
No. participants assessed at last follow-up time: median (IQR)‡	65 (37 - 125)	107 (53 - 255)	80 (46 - 146)	87 (32 - 199)
Loss to follow-up reported§	80 (69%)	129 (77%)	40 (36%)	20 (65%)
Loss to follow-up: median (IQR)§	22% (11% - 38%)	22% (7% - 37%)	14% (2% - 25%)	13% (6% - 25%)

^*In cross-sectional studies, participants were defined as eligible at the time of assessment. In cohort studies, eligible patients were defined as patients eligible for a follow-up assessment at any point in the study.

^†Time from discharge to assessment was reported using available data (i.e. means, when mean not reported, we used medians or calculated a value based on range as follows: (maximum response time - minimum response time)/2), with 4 cross-sectional and 2 cohort studies with 1 follow-up assessment not reporting time to assessment.

^‡Number of participants assessed was not reported for 7 (6%) cross-sectional studies, 8 (5%) cohort studies with 1 follow-up assessment, 14 (13%) cohort studies with ≥1 follow-up assessments, and 3 (10%) randomized clinical trials.

^§Patients known to be deceased at the time of assessment were not considered lost to follow-up.