Ulcerative colitis is not a rare complication of Takayasu arteritis

To the Editor, I read with interest the case report by Horai et al. [1] describing a 22-year-old patient who developed Takayasu arteritis (TAK) while undergoing infliximab therapy for ulcerative colitis (UC). On the basis of the case reports and registration in Japan, they estimated the complication rate for UC in patients with TAK to be 0.783 % [1, 2]. However, we believe the complication rate is much higher than this estimation. From 1990 to 2012, we treated 82 patients who were registered as having TAK. Among these patients, five were complicated with UC (Table 1); thus, the complication rate was 6.1 % (5/82), which was much higher than that reported in previous studies [1, 2]. This difference may be due to the estimation method employed in previous reports. Among 4,980 patients with TAK who were registered in Japan since 1996, 39 cases were reported to be complicated with UC at the time of previous reports. Thus, they estimated the complication rate was 0.783 % (39/4,980). However, not all the patients that developed both diseases were reported like our cases. Therefore, we are convinced that UC is not that rare in patients with TAK.