Prevalence of the aberrant right subclavian artery reported in a published systematic review of cadaveric studies: The impact of an outlier.

The aberrant or anomalous right subclavian artery (ARSA), which arises directly from the aortic arch and crosses to the right side usually behind the esophagus, is a rare but clinically important anatomical variant. A published systematic review (SR) of 15 cadaveric studies on ARSA reported that prevalence ranged from 0.2% to 13.3% of the general population; the total unweighted prevalence of ARSA was 325 cases in 13,208 bodies or 2.46%. The present review, however, found that the 13.3% figure was for 133 cases from a larger case series without a denominator. Three other studies either had an imprecise denominator or were limited to congenital conditions associated with ARSA. After exclusions and modifications, ARSA prevalence for the remaining 11 studies in the SR ranged from 0.19%, with a 95% confidence interval (CI) of 0.00-1.08%, to 2.52% (CI= 0.69-6.32%). The unweighted prevalence for all 11 studies combined was 1.23%, and the pooled prevalence estimate from a meta-analysis was 1.30% (CI = 0.86-1.82%). In conclusion, overall findings from SRs on the prevalence of rare anatomical variants such as ARSA may be affected by outliers. Clin. Anat. 30:1024-1028, 2017.