TABLE 3.

Weighted Lifetime and Current PTSD Prevalence and Mean PCL Scores According to Age Cohort in Theater Service—Discordant Twin Pairs

	PTSD
	Service in Theater				Interaction by Age
PTSD	Yes	No	Test Statistic	p	Test Statistic	p
Lifetime,a %					t(1,200) = 0.33	0.74
Age < 60	27.0 (18.1–38.3)	13.1 (7.1–22.9)	t(180) = 2.27	0.023
Age ≥ 60	13.8 (10.6–17.7)	6.9 (4.5–10.4)	t(1,022) = 2.69	0.007
Current,b %					t(1,194) = 0.55	0.58
Age < 60	18.1 (10.8–28.4)	7.2 (3.0–13.1)	t(176) = 2.23	0.026
Age ≥ 60	10.8 (7.9–14.5)	3.0 (1.6–5.3)	t(1,018) = 3.87	<0.001
PCL, mean					t(1,188) = 0.68	0.50
Age < 60	36.3 (31.9–40.6)	29.8 (26.7–32.9)	t(178) = 2.78	0.005
Age ≥ 60	27.7 (26.3–29.2)	23.1 (22.2–24.0)	t(1,010) = 7.45	<0.001

Notes: Values are percents or means, as indicated, with 95% CIs in parentheses. Prevalence and mean estimates, CIs, and p values provided for 91 theater service–discordant pairs < 60 years of age and 526 pairs ≥ 60 years. Weighted for nonresponse and to the characteristics of the living male U.S. population of Vietnam-era veterans; see also Supplemental Material.

^aDisorder classified according to DSM-IV criteria derived from the CIDI-IV.

^bCurrent refers to the last 12 months.