Put Down the ACE: Low Clinical Utility for Angiotensin-Converting Enzyme Levels in Sarcoidosis: A Single-Center Retrospective Cohort Study

Background/Objectives: ACE (angiotensin-converting enzyme) is considered a serological marker of sarcoidosis as elevated levels have been reported in 30-80% of patients. However, elevated ACE levels are also encountered in other medical conditions, and the clinical correlation between ACE levels and disease activity in sarcoidosis is disputable as well. To determine the significance of elevated ACE levels in the diagnosis and follow-up of sarcoidosis patients. Methods: All electronic patient records in which an ACE level was recorded in a large tertiary hospital were identified using a computerized algorithm. Medical diagnoses, ACE numerical values, and clinical data were also automatically extracted. Furthermore, all records with a diagnosis of sarcoidosis were manually reviewed for ascertainment of the diagnosis and searched for additional clinical manifestations and treatment responses. Results: A total of 1416 records with a documented ACE level were found in the database, and 146 of the records had a diagnosis of sarcoidosis in the medical record. However, the diagnosis was excluded in 27 of these cases after a manual review of the records. Elevated ACE levels were most commonly encountered among patients with sarcoidosis, non-Hodgkin's lymphoma, cirrhosis, and interstitial lung disease. Elevated ACE levels had a positive predictive value of 12.76% and a negative predictive value of 94.6% for the diagnosis of sarcoidosis in our cohort, with a sensitivity of 63.5% and a specificity of 59.5%. Among patients with sarcoidosis, ACE levels around the time of diagnosis were higher than ACE levels in remission. However, a paired analysis did not find a statistically significant difference in ACE levels between the two timepoints. A positive correlation between lack of cardiac involvement and elevated ACE levels was found on multivariate analysis. Conclusions: ACE levels are a non-specific serological marker with low specificity and sensitivity for sarcoidosis and a poor positive predictive value, but with a negative predictive value of 94.6%. Furthermore, elevated ACE levels correlated poorly with disease activity in our cohort.