ABSTRACT
BACKGROUND: International classification of disease (ICD) codes used to study sarcoidosis has previously been validated in only 1 study. We aimed to determine the accuracy of ICD codes to identify true sarcoidosis diagnoses in Sweden. METHODS: We identified adults with at least 2 ICD codes for sarcoidosis (ICD-10 D86) at Karolinska University Hospital 2010-2013 from the National Patient Register. Of these, we randomly sampled 100 patients for validation. We collected clinical data and categorized the diagnosis of sarcoidosis as definite, probable, or unlikely. We estimated the positive predictive value for definite and probable sarcoidosis-identified with at least 2 ICD codes-with 95% confidence intervals. RESULTS: We deemed 77% of the cases to be definite and 17% to be probable. The positive predictive value was 0.94 (95% confidence intervals = 0.87 to 0.98). CONCLUSIONS: Using at least 2 visits listing an ICD-10 code for sarcoidosis accurately identified patients with sarcoidosis from administrative health data in Sweden.
