Abstract
INTRODUCTION: Administrative health data could contribute to generalizable microscopic colitis insights, but International Classification of Diseases (ICD) codes for microscopic colitis have not been validated. METHODS: We identified individuals who received care for diarrhea in the Veterans Health Administration and classified them by receipt of microscopic colitis ICD codes. We reviewed random samples of charts to calculate the positive predictive value (PPV) and negative predictive value (NPV). We then calculated the sensitivity and specificity in clinically relevant cohorts. RESULTS: The PPV was 0.790 and the NPV was 0.995. In a cohort of individuals with diarrhea who underwent colonoscopy, the sensitivity and specificity were 0.734 and 0.996, respectively. CONCLUSION: Alternative ascertainment methods for microscopic colitis are needed because ICD codes have suboptimal performance.