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. 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.