On the connection between autoimmunity, tic disorders and obsessive-compulsive disorders: a meta-analysis on anti-streptolysin O titres.

Anti-streptolysin O (ASO) titration is useful in the context of autoimmune pathologies, including specific cases of tic and obsessive-compulsive disorders occurring after streptococcal infections. There is currently a lack of consensus on the use of ASO titres; therefore we performed a meta-analysis to systematise available data and clarify the role of ASO titres in the context of neuropsychiatric disorders. A meta-analysis was performed on ASO titration in neuropsychiatric patients, including tic disorders and obsessive-compulsive disorders. Included studies reported numbers of positive subjects, depending on a chosen threshold, or detailed ASO titrations. Three hundred and twenty nine studies were identified, of which 13 were eligible for meta-analysis. Due to limited available data, only tic disorders were evaluated. The odds ratio of finding an abnormal ASO titre in patients was 3.22 (95% C.I. 1.51-6.88) as compared to healthy controls and 16.14 (95% C.I. 8.11-32.11) as compared to non-psychiatric patients. Studies using different thresholds were generally concordant. ASO titres were also compared quantitatively, finding an overall difference of the means of 70.50 U/ml (95% C.I. 25.21-115.80) in favour of patients with tic disorders. Based on current evidence, tic disorders are associated with a significant increase in ASO titres, evident both in a threshold-level perspective and on a quantitative level. These results encourage the systematisation of ASO titration in the context of tic disorders.