Table 1

Demographic characteristics of the baseline and follow-up cohorts

Participant characteristics	Baseline cohort		Follow-up cohort		RRF (95% CI)*
Participant characteristics	n	Per cent	n	Per cent	RRF (95% CI)*
Total	2587		1526
Age (yrs)
16–35	579	22.4	268	17.6	0.78 (0.73 to 0.84)
36–50	1351	52.2	815	53.4	1.02 (0.99 to 1.05)
51+	657	25.4	443	29.0	1.14 (1.09 to 1.20)
Gender
Male	1871	72.3	1109	72.7	1.00 (0.98 to 1.02)
Female	716	27.7	417	27.3	0.99 (0.94 to 1.04)
Ethnicity
Ma¯ori	104	4.0	47	3.1	0.77 (0.61 to 0.92)
Non-Ma¯ori	2483	96.0	1479	96.9	1.01 (1.00 to 1.02)
Education
High school (secondary) or less	534	20.6	278	18.2	0.88 (0.82 to 0.95)
Polytechnic	654	25.3	368	24.1	0.95 (0.90 to 1.01)
University	1393	53.8	876	57.4	1.07 (1.04 to 1.10)
Missing	6	0.2	4	0.3
Body Mass Index
<25	1359	52.5	824	54.0	1.03 (1.00 to 1.06)
25–30	999	38.6	582	38.1	0.99 (0.95 to 1.03)
30+	214	8.3	111	7.3	0.88 (0.77 to 0.99)
Missing	15	0.6	9	0.6
Urbanicity of residence
Main urban area	2010	77.7	1218	79.8	1.03 (1.01 to 1.04)
Others	541	20.9	293	19.2	0.92 (0.86 to 0.98)
Missing	36	1.4	15	1.0
NZDep2006 scores†
1–3	1290	49.9	786	51.5	1.03 (1.00 to 1.07)
4–7	918	35.5	542	35.5	1.00 (0.96 to 1.04)
8–10	343	13.3	183	12.0	0.90 (0.82 to 0.99)
Missing	36	1.4	15	1.0
Region of residence
Auckland	918	35.5	557	36.5	1.03 (0.98 to 1.07)
Wellington	533	20.6	326	21.4	1.04 (0.97 to 1.10)
Others	1100	42.5	628	41.2	0.97 (0.93 to 1.01)
Missing	36	1.4	15	1.0

*95% bootstrap CI.
†2006 New Zealand Deprivation Index with decile 10 the most deprived neighbourhood and decile 1 the least.
RRF, ratios of relative frequencies.