Purpose: Sarcoidosis is a disease with heterogenous clinical presentations. Diagnosis of sarcoidosis is often challenging with the lack of gold standard tests. In this study, we investigated the diagnostic utility of angiotensin-converting enzyme (ACE) for diagnosis of sarcoidosis.
Methods: A cohort of Olmsted County, Minnesota residents who were diagnosed with sarcoidosis between January 1, 1984 and December 31, 2013 was identified based on individual medical record review. ACE levels recorded in the medical records of all subjects at the time of diagnosis were extracted. Comparator subjects were residents of Olmsted County, Minnesota who had ACE levels tested the same time period but did not have a diagnosis of sarcoidosis. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the c-statistic of high versus low/normal ACE to diagnose sarcoidosis were calculated.
Results: A total of 3277 Olmsted County residents age ≥18 years had at least one ACE test in 1984-2013. The sarcoidosis incidence cohort contained 295 Olmsted County residents diagnosed with sarcoidosis in 1984-2013. Of these, ACE tests were obtained in 251. The sensitivity and specificity of high ACE for diagnosis of sarcoidosis were 41.4 % (95 % CI 35.3-47.8 %) and 89.9 % (95 % CI 88.8-91.0 %), respectively. The PPV and NPV in this population were 25.4 % (95 % CI 21.3-29.9 %) and 94.9 % (95 % CI 85.0-87.4 %).
Conclusions: This study demonstrated a poor sensitivity and insufficient specificity of high ACE for diagnosis of sarcoidosis suggesting a limited role of ACE in clinical practice.
Keywords: Autoimmune disease; Clinical epidemiology; Diagnostic testing; Sarcoidosis.