LAUSR

Recently, there are several studies reporting that pre-existing chronic kidney disease (CKD) was related to the adverse outcomes of patients with coronavirus disease 2019 (COVID19) [1, 2]. Moreover, a meta-analysis has indicated that CKD was associated with poor prognosis in patients with COVID-19 on the basis of unadjusted effect estimates [3]. To the best of our knowledge, several factors including age, gender and underlying diseases were reported to have effects on the clinical outcomes of COVID-19 patients [4]. Therefore, in this present meta-analysis, we aimed to investigate the relationship between CKD and the adverse outcomes in COVID-19 patients on the basis of adjusted effect estimates by performing a quantitative meta-analysis. The electronic databases including PubMed, Web of Science, EMBASE and Chinese National Knowledge Infrastructure (CNKI) were searched by two independent authors to screen out eligible articles, using the keywords of “coronavirus disease 2019” OR “SARS-CoV-2” OR “2019 novel coronavirus” OR “2019-nCoV” OR “COVID-19” AND “chronic kidney disease” OR “chronic renal disease” (up to July 15th, 2020). The adverse outcomes were defined as severe illness, critical illness or death. Studies reporting the adjusted effect estimates (odds ratio (OR) or hazard ratio (HR)) on the association between CKD and adverse outcomes of COVID-19 patients were eligibly included. All analyses were performed by STATA 11.2. A fixed-effects model was used if I2 was < 50%. Otherwise, a randomeffects model was applied. The stability of results was assessed by sensitivity analysis. Publication bias was evaluated by Begg’s test and Egger’s test. A total of 179 articles were identified. Finally, 13 articles with 12,999 patients were included in the study. The main characteristics of the included studies are shown in Table 1. Our results indicated that COVID-19 patients with a history of CKD had an increased risk for adverse outcomes (pooled effect = 1.64, 95% CI 1.28–2.09) (Fig. 1a). We also observed that CKD was significantly associated with an increased risk for COVID-19 death while adverse outcomes were only restricted to death (pooled effect = 1.67, 95% CI 1.28–2.17) (Fig. 1b). There was no publication bias (Begg’s test, P = 0.855 (Fig. 1c) and Egger’s test, P = 0.655). Sensitivity analysis exhibited that our results were stable (Fig. 1d). Previous meta-analyses have reported the association of CKD with poor outcomes including mortality among COVID-19 patients, but their findings were based on unadjusted effect estimates [5–10]. Our present study based on adjusted effect estimates indicated that pre-existing CKD was independently associated with an increased risk for adverse outcomes, especially for mortality. Thus, co-existing CKD patients should be taken care not to get COVID-19 infection. Of course, there are some limitations to this study. First, the patients in each article might be in different stages of the disease, which may have a certain impact on the overall effects. Second, supportive treatment and medications are not clear in the included studies, thus, the data could not be analyzed currently. Third, the included studies were mainly from China, USA and Italy. As a result, it should be cautious to extrapolate the inclusion to other regions. Fourth, the findings were based on the adjusted effect estimates, but the adjusted factors were not completely consistent. This issue should be addressed in the future studies. Taken together, our current study is needed to be verified by further welldesigned studies with a large sample size. * Haiyan Yang [email protected]