Change in prevalence of post-traumatic stress disorder in the two years following trauma: a meta-analytic study

Figures & data

Figure 1. PRISMA flow diagram outlining the process of screening studies for inclusion in the review. PTSD, post-traumatic stress disorder.

Table 1. Results from the meta-analyses conducted at each time-point after trauma exposure, showing pooled prevalence of post-traumatic stress disorder (PTSD) up to 24 months.

Time since trauma	PTSD prevalence
	%	95% CI	k	n	I^2
1 month	27.0	21.7–32.56	43	6606	96
3 months	17.6	14.27–21.23	56	10,831	95
6 months	19.5	15.82–23.47	39	7323	94
9 months	21.4	8.41–28.09	7	1557	98
12 months	16.9	13.62–20.39	36	8812	94
24 months	20.7	12.33–30.61	6	2101	96

Note: CI, confidence interval; k, number of studies included in each meta-analysis; n, total number of participants included in each of the meta-analyses.

Table 2. Results from the meta-analyses of the changes in absolute post-traumatic stress disorder (PTSD) prevalence between time-points, as measured by risk difference.

	Change in PTSD prevalence
	%	95% CI	k	n	I^2	p
1–3 months	−9	−13.6 to −4.4	28	3288	87	0.0001
1–6 months	−5.8	−10.1 to −1.6	20	3953	81	0.007
1–12 months	−8.9	−15.1 to −2.8	12	2744	87	0.004
3–6 months	−0.6	−2.7 to 1.6	18	3292	29	0.615
3–12 months	−2.4	−4.1 to −0.1	26	7231	55	0.004
6–12 months	−2.1	−3.7 to −0.04	18	4245	0	0.016
12–24 months	0	−3.2 to 3.2	5	2212	47	0.989

Note: CI, confidence interval; k, number of studies included in each meta-analysis; n, total number of participants included in each of the meta-analyses; I², percentage of variation due to heterogeneity.

Table 3. Results from the meta-analyses conducted at each time-point after trauma exposure comparing post-traumatic stress disorder (PTSD) prevalence following either intentional or unintentional trauma exposure.

Time since trauma	Intentional trauma				Intentional trauma excluding police/military^a				Unintentional trauma				Contrasts
	PTSD prevalence				PTSD prevalence				PTSD prevalence				A vs C	B vs C
	% (95% CI)	k	n	I^2	% (95% CI)	k	n	I^2	% (95% CI)	k	n	I^2	p	p
1 month	32.1 (15.6–51.2)	10	1541	98	42.4 (29.4–55.6)	8	846	93	25.6 (20.6–30.8)	33	6606	94	.502	0.017
3 months	16.4 (7.6–11.1)	7	1068	94	23.5 (12.7–36.3)	5	592	90	17.8 (14.2–21.7)	48	9763	96	.852	0.338
6 months	21.2 (14.0–29.4)	5	773	83	24.0 (17.4–31.3)	4	472	61	19.3 (15.4–23.6)	35	6550	94	.674	0.235
12 months	13.3 (2.3–17.3)	4	443	93	–	–	–		17.3 (13.9–21.0)	32	8369	94	.638	–

Note: ^aIntentional trauma exposure excluding police (k = 1) and military (k = 1) samples. PTSD prevalence represents pooled prevalence across studies.

CI, confidence interval; k, number of samples included in each meta-analysis; n, total number of participants included in each meta-analysis.

Table 4. Results from the meta-analyses conducted at each time-point after trauma exposure comparing post-traumatic stress disorder (PTSD) prevalence following self-report measures and diagnostic interviews.

Time since trauma	Diagnostic interview					Self-report					Contrast
	PTSD prevalence					PTSD prevalence
	%	95% CI	k	n	I^2	%	95% CI	k	n	I^2	p
1 month	22.2	15.3–29.9	11	1341	90	28.5	22.0–35.4	32	5265	96	0.225
3 months	11.0	8.1–14.4	15	3952	89	20.1	15.7–25.0	41	6879	95	0.001
6 months	15.6	9.9–22.3	9	1343	88	20.6	16.4–25.2	30	5980	94	0.213
12 months	9.7	6.0–14.2	10	3125	93	20.0	16.0–24.4	26	5687	92	0.001

Note: CI, confidence interval; k, number of samples included in each meta-analysis; n, total number of participants included in each meta-analysis.

Table 5. Meta-regression of point prevalence.

Time-point	Moderator	k	Qm	b1	z	I^2	R^2
1 month	Male	41	3.7	−0.0023*	−1.92	95.6%	7.11%
	Age	36	6.1	−0.012*	−2.47	95.15%	12.6%
3 months	Male	54	8.9	−0.0024**	−2.97	94.69%	13.66%
	Age	45	3.2	−0.005	−1.79	94.57%	4.7%
6 months	Male	37	< 0.001	< 0.0001	0.008	92.73%	0.0%
	Age	32	1.21	−0.0025	−1.10	91.53%	0.5%
12 months	Male	35	2.58	−0.002	−1.61	94.82%	4.71%
	Age	25	0.57	0.0025	0.75	93.94%	0.00%

Note: k, number of studies; Qm, test statistic of moderator; B₁, unstandardized beta estimate; I², estimate of unaccounted heterogeneity; R², estimate of heterogeneity accounted for by moderator.

*p < .05, **p < .01.