Table 1.

Reported reasons for attrition

Reported reason	Studies, n (%) (N = 19)a	Participants, n (%) (N = 329)b	References
Potentially modifiable reasons
Capability Pain during exercise Too tired Medical reasons (related to protocol)	4 (21.1) 1 (5.3) 1 (5.3) 2 (10.5)	6 (1.7) 2 (0.6) 1 (0.3) 3 (0.9)	32,40,43,44
Opportunity Family reasons (e.g. family member illness) Too busy Participation requires too much time Job commitments Schedule conflictb Engaged in other activities Enrolled in another study Noncompliance with study protocol	5 (26.3) 2 (10.5) 1 (5.3) 1 (5.3) 1 (5.3) 1 (5.3) 1 (5.3) 1 (5.3) 1 (5.3)	20 (5.8) 2 (0.6) 1 (0.3) 2 (0.6) 1 (0.3) – 11 (0.9) 1 (0.3) 2 (0.6)	29,31,32,38,42
Motivation Lacked interest Low motivation Too much trouble Wanted to lose weightc Physiotherapist perceives rehabilitation needs not met by program	5 (26.3) 2 (10.5) 1 (5.3) 1 (5.3) 1 (5.3) 1 (5.3)	55 (15.9) 9 (2.6) 9 (2.6) 32 (9.2) 1 (0.3) 4 (1.2)	32,33,35,38,43
Discontinued for unspecified reason	7 (36.8)	78 (22.5)	30,31,33,34,39,40,42
Lost to follow-up	3 (15.8)	19 (5.5)	33,38,48
Potentially non-modifiable reasons
Death Declining health (unrelated to protocol) Hospitalization Surgical intervention preventing participation Participant moved residence Personal reasons (unrelated to protocol)	12 (63.2) 7 (36.8) 3 (15.8) 1 (5.3) 3 (15.8) 2 (10.5)	59 (17.0) 70 (20.2) 20 (5.8) 2 (0.6) 14 (4.0) 4 (1.2)	29–31,33,34,36–41,43,44,50,51

^a One study did not report reasons for attrition

^b One study did not report reasons for attrition by participant (Langlois 2013)

^c Another intervention arm in this study was “weight loss” where participants received a diet intervention