An Observational Study of Sex Differences in Takayasu Arteritis in China: Implications for Worldwide Regional Differences

Background: This study analyzes the demographics of patients affected by Takayasu arteritis (TA). The study further explores the correlation and other contributory factors to the regional differences between the ratios of females to males (sex ratio). Methods: This was a retrospective study using 1,011 clinical cases diagnosed with TA (as per 1990 American College of Rheumatology criteria) between 1982 and 2015 collected from the Peking Union Medical College Hospital (PUMCH) database. Literature review of TA studies published from 1992 to 2016 via the PubMed search was also conducted with exclusion of the studies less than 50 cases. General characteristics, sex ratios and regional differences worldwide, sex ratio variation in different age group, relationship between sex ratio and gross domestic product (GDP) per capita, and main lesion involved in different sexual group were statistically analyzed. Results: The average age of these 1,011 patients was 32.5 +/- 15.1 years, with 763 women comprising 75.5% of the cohort, giving a female-to-male ratio (F:M ratio) of 3.1:1. The F:M ratio of TA patients at PUMCH was equal to that of a previous study from China, but significantly lower than that in Japan, Italy, Turkey, Mexico, Korea (all P < 0.05), but higher than that in India (P < 0.05), and Thailand (although not statistically significant at P = 0.08). The sex ratio of TA patients between PUMCH and Japanese databases significantly differed at all age groups (P < 0.05), with the exception of the youngest (<= 9 years; P = 0.57) and oldest (>= 70 years; P = 0.32) patients. A significant correlation between the TA F:M ratio and GDP per capita was observed, with a correlation coefficient of rho = 0.730 (P = 0.04). A sex difference in lesion distribution was also observed: women had significantly more aortic arch involvement (P = 0.02), whereas lower limb artery involvement was more frequent in men (P < 0.001). Conclusions: The sex ratio of patients with TA in China significantly differed from that in many other countries. Genetics, dietary habits, and environmental conditions may affect the incidences of TA in female versus male patients. Aortic arch branch vessels are involved more frequently in women; renal artery and iliac artery involvements are more common in men.