Letter: chronic kidney disease risk in patients with chronic hepatitis B—authors’ reply

EDITORS,

We would like to express our gratitude to Dr Xin et  al for their insightful comments on our study.1, 2 We fully acknowledge that the use of other formulae, namely the Cockroft-Gault formula and Modification of Diet in Renal Disease Study (MDRD-4), to estimate glomerular filtration rate (eGFR) might have yielded different results.3 Application of the Cockroft-Gault formula often results in better estimated renal function.4 Nonetheless, the impact of entecavir and tenofovir disoproxil fumarate on serial renal function would be established with any of these formulae as they establish the relative change in eGFR. Including clinical renal events, namely renal replacement therapy and renal transplantation, may confirm the robustness of these formulae.5 Unfortunately the incidence rates of these renal events were small even with such a large sample size.

Serial hepatitis B virus (HBV) markers were collected throughout the study. Approximately 50% of the patients had serum HBV DNA results available at 12 months; 87.8% had undetectable HBV DNA (<20 IU/ml).6 In the subgroup of patients who had detectable serum HBV DNA at 12 months, there was no difference in the incidence rate of progression in chronic kidney disease (CKD) stage. In fact we expect complete viral suppression in most of the patients who received these potent nucleos(t)ide analogues.7, 8 Even with detectable serum HBV DNA, the level would be generally low.9 Hence, we may not expect to see an obvious difference in CKD progression even in patients who failed to achieve complete viral suppression.