Systematic review and meta analysis A systematic review and meta-analysis of the incidence rate of Takayasu arteritis

Objectives: Takayasu arteritis (TAK), is a rare autoimmune rheumatic disease causing large vessel vasculitis. Onset is typically between the ages of 20-30. It is associated with substantial morbidity and mortality, notably due to its effects on the cardiovascular system. It has a poorly understood global epidemiology. Our objective was to systematically review the available evidence in order to calculate the incidence rate of TAK. Methods: Three databases (Medline, PubMed and Embase) were searched in November 2019 and the results were screened by two reviewers. A random effects meta-analysis was then conducted in R to calculate the overall incidence rate. Heterogeneity was assessed using I2. The quality of the studies was assessed using an adapted Newcastle-Ottawa scale. Further sub-group analyses were performed by quality, sex, research setting and geographical location. Publication bias was assessed using a Beggs funnel plot. Results: The incidence rate for TAK per million person-years with 95% confidence intervals was 1.11 per million person years (95% CI 0.75 - 1.65). The heterogeneity in the data was extremely high in all analyses, which suggests that there was considerable variation in incidence rates across the different populations studied. TAK was found to be more common in women (incidence rate 2.01 per million person-years, 95% CI 1.39 - 2.90). Conclusions: TAK is an extremely rare disease. It affects women more commonly than men. There is considerable variation in the incidence rate between populations. We suggest that future research should focus on discrete populations in order to better identify genetic and environmental risk factors.