Diagnostic aspects of angiotensin converting enzyme in pulmonary sarcoidosis

Angiotensin converting enzyme (ACE) has been measured in 102 biopsy-proven sarcoid patients, 70 patients diagnosed by clinical and radiological methods and 74 nonsarcoid patients as controls. The distributions of the various groups have been examined, and the effects of stage of disease, disease activity and prednisone treatment have been evaluated. Receiver operating characteristic (ROC) curves have been established for ACE, and the appropriateness of various statistical procedures is discussed. We have not discerned any effect of stage of sarcoidosis or of extent of disease activity on ACE values. The ROC curves suggest an upper limit of normal of about 50 U/L for our assay, and a sensitivity of 63% and specificity of 93%, yielding predictive values of 93% for a positive result and 74% for a negative result, with a likelihood ratio of 3.6. The results are discussed in the context of other work on ACE and in relation to the more invasive procedures of bronchoalveolar lavage and Gallium scan.