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, 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.

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.