Serum Albumin as a Biomarker of Pulmonary Sarcoidosis Chronicity.

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.A retrospective study was conducted to investigate independent biomarkers of pulmonary sarcoidosis duration.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, p<0.0001) for serum albumin and an AUC of 0.665 (95% CI 0.561-0.768, p<0.004) for age. An albumin level <2.4 gm/dL yielded a 90.5% sensitivity and 98.2% specificity for predicting sarcoidosis of >10 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.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.