. 2013 Jun 25;8(6):e66227. doi: 10.1371/journal.pone.0066227

Table 6. Subgroup analyses of study design, type of PTSD assessed and quality characteristics in the Meta-Analysis of 5-HTTLPR polymorphisms and Post-traumatic Stress Disorder (PTSD) in the triallelic approach.

	K^‡	Number of participants			Frequency Model^#								Dominant Model								Recessive Model
					OR		95%CI		I² (%)		P-value ^&		OR		95%CI		I² (%)		P-value ^&		OR		95%CI		I² (%)	P-val ue ^&
Case representativeness
Yes	1	96			1.10		0.56, 2.17		NA				1.63		0.54, 4.95		NA				0.75		0.22, 2.50		NA
No	6	4055			1.13		0.80, 1.58		77		0.96		0.97		0.68, 1.40		50		0.39		1.41		0.73, 2.73		83	0.37
Control representativeness
Yes	7	4151			1.09		0.80, 1.49		73				1.02		0.73, 1.42		43				1.31		0.71, 2.41		80
No	0	0			NA		NA		NA		NA		NA		NA		NA		NA		NA		NA		NA	NA
Same diagnostic instrument
Yes	7	4151			1.12		0.83, 1.53		73				1.02		0.73, 1.42		43				1.31		0.71, 2.41		80
No	0	0			NA		NA		NA		NA		NA		NA		NA		NA		NA		NA		NA	NA
Trauma exposed control
Yes	7	4151			1.12		0.83, 1.53		73				1.02		0.73, 1.42		43				1.31		0.71, 2.41		80
No	0	0			NA		NA		NA		NA		NA		NA		NA		NA		NA		NA		NA	NA
Same principal trauma for PTSD and controls
Yes	3	1020		1.76			0.83, 2.31		0				0.99		0.65, 1.49		0				2.45		1.05, 5.72		59
No	4	3131		0.99			0.72, 1.35		62		0.006		1.09		0.64, 1.86		66		0.75		0.92		0.57, 1.49		48	0.05
Assessment of ethnicity
Yes	7	4151		1.12			0.83, 1.53		73				1.02		0.73, 1.42		43				1.31		0.71, 2.41		80
No	0	0		NA			NA		NA		NA		NA		NA		NA		NA		NA		NA		NA	NA
Presence of blind assessment
Yes	1	388		1.09			0.67, 1.77		82				1.13		0.70, 1.82		NA				4.04		2.49, 6.54		NA
No	6	3763		1.19			0.98, 1.45		0		0.75		0.98		0.63, 1.52		52		0.67		1.02		0.69, 1.51		34	<0.0001
Reporting of quality control procedures in genotyping methods
Yes	5	2857		1.09		0.67, 1.77			82				0.94		0.63, 1.39		34				1.20		0.48, 3.05		85
No	2	1294		1.19		0.98, 1.45			0		0.75		1.06		0.43, 2.62		44		0.81		1.29		0.74, 2.25		22	0.90
Reporting HWE^†
Yes	4	3345		1.13		0.71, 1.79		86				0.93		0.58, 1.50		67				1.49		0.59, 3.76		90
No	3	806		1.13		0.80, 1.59		0		0.99		1.19		0.67, 2.10		0		0.52		1.14		0.65, 2.01		0		0.63
Adjustment for potential confounders
Yes	6	4109		1.12		0.80, 1.56		78				1.05		0.74, 1.48		47				1.22		0.63, 2.35		83
No	1	42		1.18		0.50, 2.81		NA		0.91		0.47		0.10, 2.21		NA		0.32		2.50		0.67, 9.31		NA		0.34
Control for multiple comparisons
Yes	3	550		1.65		1.29, 2.09		0				1.11		0.74, 1.67		0				2.55		1.22, 5.32		61
No	4	3601		0.92		0.63, 1.35		69		0.01		0.97		0.56, 1.69		67		0.70		0.85		0.53, 1.38		40		0.01
Psychiatric comorbidity assessed
Yes	6	3561		1.15		0.82, 1.62		77				1.04		0.72, 1.51		50				1.35		0.69, 2.66		83
No	1	590		0.91		0.47, 1.73		NA		0.52		0.76		0.28, 2.03		NA		0.55		1.05		0.34, 3.21		NA		0.70
Study design
Case-Control	4		3601	0.92		0.63, 1.35		69				0.97		0.56, 1.69		67				0.85		0.53, 1.38		40
Cohort	3		550	1.65		1.29, 2.09		0		0.01		1.11		0.74, 1.67		0		0.70		2.55		1.22, 5.32		61		0.01
Type of PTSD assessed
Lifetime PTSD	4		3131	1.00		0.69, 1.45		71				1.09		0.64, 1.86		66				0.92		0.57, 1.49		48
Current PTSD	2		430	1.76		1.34, 2.31		0				1.00		0.56, 1.79		11				3.82		2.43, 6.00		0
Last 6 months	1		590	0.91		0.47, 1.73		NA		0.02		0.76		0.28, 2.03		NA		0.82		1.05		0.34, 3.21		80		<0.0001

^‡

K: Number of studies; ^#Number of alleles S or L duplicates the number of participants as each participant has two alleles (S, L or one of each one); OR: Odds Ratio; 95% CI: 95% Confident Interval; ^&Chi-squared test for subgroup differences; NA: Not applicable; ^†HWE: Hardy-Weinberg Equilibrium.