Fig 2.
Association between interleukin (IL)-6 plasma levels and obsessive-compulsive disorder (OCD) stratified by age and medication use. Meta-analysis failed to demonstrate a significant association between IL-6 plasma levels and OCD (standardized mean difference [SMD], 0.15 [95% CI, −0.12–0.41]; z=1.1; P=0.28). There was a large degree of heterogeneity between trials that failed to reach statistical significance (χ2=6.2; df=4; P=0.18; I2=36%). In stratified subgroup analysis, there was a significant moderating effect of subject age and inclusion of subjects with current medication use on the association between IL-6 levels and OCD (χ2 test for subgroup differences=5.2; df=1; P=0.02). We were not able to disentangle the possible influence of these two factors, as there were no adult studies that included subjects with current medication use and no children’s studies that excluded subjects with medication use