Table 1a.

Age-period-cohort analysis of prescription opioid (PO) initiation.

Birth year	Subsample size	POs ever*	% of birth cohort initiating PO use in each time period
			Premilitary (n.s.)	In military (n.s.)	Postmilitary (n.s.)
<1970	53	82.7	22.6	32.1	26.4
1970–1979	53	96.2	28.3	32.1	35.8
1980–1984	45	95.6	24.4	40.0	28.9
1985+	63	93.7	31.7	42.9	19.0
Overall	214	92.0	27.1	36.9	27.1

^*Difference across birth cohorts significant at the α = .05 level.

n.s.: Differences across birth cohorts not significant at even the α = .10 level.