A randomised controlled trial comparing opt-in and opt-out home visits for tracing lost participants in a prospective birth cohort study

Table 5 Mean resource use, cost and total cost per participant and overall total cost

	Mean resource use per participant			Mean cost per participant (£)
Resource	Opt-in N = 145	Opt-out N = 139	Unit cost (£)	Opt-in N = 145	Opt-out N = 139
Travel per visit (number of visits)	0.34	3.60	2.05	0.69	7.36
Attempted and actual home visits (number of visits))	0.34	3.60	15.18^b	5.13	54.60
Telephone calls-landline and mobile (number of calls)	0.28	1.29	6.00^a	1.70	7.77
Other contact (number of contacts))	0.10	0.37	6.00^a	0.62	2.20
Total mean cost per participant				8.14	71.93
Total cost				1180.07	9998.93
Number of participants who consented				4	46

^aThese unit costs were based on an assumption of each telephone call/other contact lasting 10 min, using the MORI cost per hour of a fieldworker of £36
^bIpsos MORI were only able to give a total cost of fieldwork (£8,600). In order to obtain the unit cost, the cost of the telephone calls and other contacts were subtracted from this cost, prior to being divided by the total number of events in the study

ISSN: 1471-2288