Serum uric acid levels and uric acid/creatinine ratios: affordable biomarkers for predicting chronic obstructive pulmonary disease severity and exacerbations

Background Chronic obstructive pulmonary disease (COPD) is an essential initiate the conditions of mortality and morbidity. Objective This study evaluated the clinical importance of measuring the level of serum uric acid (sUA) level and uric acid/creatinine (UA/Cr) ratio in stable COPD patients as objective biomarkers of disease severity and exacerbations Participants and methods The research involved 283 stable COPD patients and 123 healthy controls. The sUA levels and sUA/Cr ratios in both groups were assessed and compared; their correlations with the clinical, class of severity, number of exacerbations per year, spirometry parameters, oxygen saturation, and C-reactive protein were investigated. Linear regression analysis was done to examine the most predictors for severity and exacerbations, receiver operating characteristic curve for risk of exacerbation, and severity of COPD were reported to study the cut-off values, sensitivity, and specificity of both sUA and UA/Cr ratio. Results There were significant correlations between both sUA, and UA/Cr ratio with the number of exacerbations and hospitalizations per year, all spirometry data, and C-reactive protein. A linear regression shows significance (F=374, P< 0.001) and accounts for 88% of exacerbation frequency. The most powerful predictors were UA/Cr ratio [95% confidence interval (95% CI): 0.003-0.047] followed by UA (95% CI: 0.021-0.195) and then smoking (95% CI: 0.029-0.045). Receiver operating characteristic curves for the evaluation of the performance of both UA levels and calculated UA/Cr ratio in predicting the frequency of exacerbations revealed that UA has a lower predicting power for an exacerbation cut-off value of 4.050 (sensitivity: 0.98, specificity: 0.93), whereas the UA/Cr ratio had a good power of prediction for exacerbation; the cut-off value was 8.49 (sensitivity: 0.99, specificity: 0.57). Conclusion The measurement of sUA levels and the calculated sUA/Cr ratio estimation have a supplementary role in anticipating the severity of COPD and in predicting future exacerbations.