The MRC National Survey of Health and Development reaches age 70: maintaining participation at older ages in a birth cohort study

Table 2 Odds ratios (95% confidence intervals) of overall participation and home visit participation at 68–69 years by lifetime and recent contact

	Odds ratio (95% confidence intervals)
	Overall participation (n = 2499)		Home visit participation (n = 2404)
	Model 1	Model 2	Model 1	Model 2
Number of lifetime contacts (per category)	1.2 (1.0, 1.4)	1.2 (1.0, 1.4)	1.1 (1.0, 1.3)	1.1 (1.0, 1.3)
p value	0.02	0.02	0.01	0.01
Contact at age 60–64
PQ + CV	1.0	1.0	1.0	1.0
PQ + HV	0.61 (0.32, 1.2)	0.83 (0.43, 1.6)	0.30 (0.21, 0.41)	0.37 (0.26, 0.52)
CV only	0.20 (0.10, 0.40)	0.22 (0.11, 0.44)	0.38 (0.22, 0.66)	0.41 (0.24, 0.72)
HV only	0.11 (0.05, 0.28)	0.16 (0.06, 0.40)	0.09 (0.05, 0.18)	0.12 (0.06, 0.23)
PQ only	0.13 (0.08, 0.21)	0.16 (0.10, 0.27)	0.05 (0.04, 0.07)	0.06 (0.04, 0.08)
Temporary refusal	0.03 (0.01, 0.05)	0.03 (0.02, 0.05)	0.04 (0.03, 0.06)	0.05 (0.03, 0.07)
Newly traced or returned to GB	0.09 (0.05, 0.16)	0.11 (0.06, 0.19)	0.14 (0.09, 0.22)	0.15 (0.10, 0.24)
p value	<0.001	<0.001	<0.001	<0.001

Model 1: Adjusted for sex, lifetime contact and recent contact (i.e. mutually adjusted)
Model 2: Model 1 + education qualifications, adult occupational class, childhood cognitive ability