Authors' reply to Zhang et al

We would like to thank Zhang et al. [1] for their interest in our observational study, showing a significant positive association between circulating levels of serum uric acid (SUA) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients with coronary artery dis- ease and without overt heart failure [2]. Specifically, Zhang et al. asked if in our study the association between SUA levels and NT-proBNP concentrations was different between men and women [1]. Among the 171 patients included in our study [2], there were 120 men and 51 women. Levels of SUA did not differ significantly between men and women (mean ± SD: 0.41 ± 0.11 vs. 0.39 ± 0.13 mmol/L, p = 0.43). Similarly, the results were comparable when we examined the association between SUA and NT-proBNP levels in men and women, separately. In men, we found that patients in the 3rd SUA tertile had a significantly higher risk of having elevated NT-proBNP concentrations (standardized β coefficient 0.331, p = 0.002) compared to those in 1st SUA tertile. In women, we found that patients in the 3rd SUA tertile had a significantly higher risk of having increased NT-proBNP concentra- tions (standardized β coefficient 0.569, p < 0.001). Both of these results remained unchanged after adjustment for age (standardized β coeffi- cient 0.328, p = 0.001 for men, and standardized β coefficient 0.532, p < 0.001 for women). Overall, therefore, these additional statistical analyses clearly sug- gest that in our study the significant positive association we observed between SUA and NT-proBNP concentrations was consistent in both sexes.