Gender, age, and concomitant diseases of melanosis coli in China: a multicenter study of 6,090 cases

Melanosis coli (MC) is a noninflammatory, benign, and reversible colonic disorder, but its detection rates in China are unclear. We therefore aimed to analyze the epidemiological characteristics of MC in China. We assessed the detection rates, associated factors and concomitant diseases of MC in the patients who underwent colonoscopy at eight medical centers across five regions of China between January 2006 and October 2016. All data were procured from the electronic database established at each participating institutions. Among the 342,922 included cases, MC was detected in 6,090 cases (detection rate = 1.78%, 95% confidence interval, 1.73%-1.82%) at a mean age of 60 years. The detection rate gradually increased yearly, and along with the increasing age regardless of gender, while a rapid increase presented in the patients ≥60 years of age (0.58% for ≤25 years, 1.22% for 25-59 years, and 3.19% for ≥60 years). The detection rate was higher in females than in males; however, the rate of per-year increase was higher in males than in females at age of ≥60 years, which was 1.85-fold of that in females. Among cancer, polyp, inflammation, and diverticula, polyp was the most common concomitant disease of MC and identified in 41.72% of MC patients. MC detection rates were increased annually and elevated in older patients, particularly in male patients. Males in the elderly population of ≥60 years were most likely to have MC. Colonic polyp is the most common concomitant disease of MC.