Serum Albumin as a Biomarker of Pulmonary Sarcoidosis Chronicity

OBJECTIVES: The duration of sarcoidosis is associated with a higher risk of irreversible pulmonary fibrosis. Sarcoidosis shows diverse clinical presentations, which may lead to a delayed diagnosis due to lack of a specific diagnostic test. Biomarkers of sarcoidosis duration have not been previously explored. MATERIALS AND METHODS: A retrospective study was conducted to investigate independent biomarkers of pulmonary sarcoidosis duration. RESULTS: A total of 108 cases with pulmonary sarcoidosis (mean age 53.4 years; 76.9% females; average duration of sarcoidosis 12 years) were included in the study. We found significant correlation between the duration of sarcoidosis and serum albumin levels (r=−0.414, p=0.0001), sedimentation rate (r=0.375, p=0.001), pulmonary artery systolic pressure (r= 0.468, p=0.003), diffusion capacity (r=−0.334, p=0.002), and age (r=0.492, p=0.0001). A multivariate linear regression analysis revealed that serum albumin levels (β=−5.242, 95% confidence interval [CI] −8.372 to −2.112, p=0.001) and age (β=0.367, 95% CI 0.164 to 0.570, p=0.001) were independent correlates of sarcoidosis duration. A receiver operating characteristics curve analysis for prediction of sarcoidosis of a >10 years duration gave an area under curve (AUC) of 0.722 (95% CI 0.620–0.824, p10 years duration. In comparison, the patient age of 51.5 years yielded a 70.2% sensitivity and 50% specificity for predicting patients with sarcoidosis for >10 years. CONCLUSION: The serum albumin level may be a biomarker of pulmonary sarcoidosis duration and chronicity of disease. Further investigations are required to confirm its predictive ability.