Mortality analysis of COVID-19 infection in chronic kidney disease, haemodialysis and renal transplant patients compared with patients without kidney disease: a nationwide analysis from Turkey

Abstract

Background: Chronic kidney disease (CKD) and immunosuppression, such as in renal transplantation (RT), stand as one of the established potential risk factors for severe coronavirus disease 2019 (COVID-19). Case morbidity and mortality rates for any type of infection have always been much higher in CKD, haemodialysis (HD) and RT patients than in the general population. A large study comparing COVID-19 outcome in moderate to advanced CKD (Stages 3-5), HD and RT patients with a control group of patients is still lacking.

Methods: We conducted a multicentre, retrospective, observational study, involving hospitalized adult patients with COVID-19 from 47 centres in Turkey. Patients with CKD Stages 3-5, chronic HD and RT were compared with patients who had COVID-19 but no kidney disease. Demographics, comorbidities, medications, laboratory tests, COVID-19 treatments and outcome [in-hospital mortality and combined in-hospital outcome mortality or admission to the intensive care unit (ICU)] were compared.

Results: A total of 1210 patients were included [median age, 61 (quartile 1-quartile 3 48-71) years, female 551 (45.5%)] composed of four groups: control (n = 450), HD (n = 390), RT (n = 81) and CKD (n = 289). The ICU admission rate was 266/1210 (22.0%). A total of 172/1210 (14.2%) patients died. The ICU admission and in-hospital mortality rates in the CKD group [114/289 (39.4%); 95% confidence interval (CI) 33.9-45.2; and 82/289 (28.4%); 95% CI 23.9-34.5)] were significantly higher than the other groups: HD = 99/390 (25.4%; 95% CI 21.3-29.9; P < 0.001) and 63/390 (16.2%; 95% CI 13.0-20.4; P < 0.001); RT = 17/81 (21.0%; 95% CI 13.2-30.8; P = 0.002) and 9/81 (11.1%; 95% CI 5.7-19.5; P = 0.001); and control = 36/450 (8.0%; 95% CI 5.8-10.8; P < 0.001) and 18/450 (4%; 95% CI 2.5-6.2; P < 0.001). Adjusted mortality and adjusted combined outcomes in CKD group and HD groups were significantly higher than the control group [hazard ratio (HR) (95% CI) CKD: 2.88 (1.52-5.44); P = 0.001; 2.44 (1.35-4.40); P = 0.003; HD: 2.32 (1.21-4.46); P = 0.011; 2.25 (1.23-4.12); P = 0.008), respectively], but these were not significantly different in the RT from in the control group [HR (95% CI) 1.89 (0.76-4.72); P = 0.169; 1.87 (0.81-4.28); P = 0.138, respectively].

Conclusions: Hospitalized COVID-19 patients with CKDs, including Stages 3-5 CKD, HD and RT, have significantly higher mortality than patients without kidney disease. Stages 3-5 CKD patients have an in-hospital mortality rate as much as HD patients, which may be in part because of similar age and comorbidity burden. We were unable to assess if RT patients were or were not at increased risk for in-hospital mortality because of the relatively small sample size of the RT patients in this study.

Keywords: COVID-19; haemodialysis; kidney disease; mortality; renal transplantation.

FIGURE 1

Consort of the study illustrating population selection. Control group: four patients with acute kidney injury (AKI), two patients without outcome data, one patient due to pregnancy. HD group: 12 peritoneal dialysis patients, 5 patients still at the hospital, 2 patients without outcome data, 1 patient reported congestive heart failure without confirmed COVID-19. CKD group: six patients with AKI, three patients without outcome data.

FIGURE 2

Kaplan–Meier plots of patient survival. (A) All patient groups were compared in terms of mortality. The median duration for the mortality was 30 days in the HD group, >20 days in the RT group, 22 days in the CKD group and >30 days in the control group. The mean duration for mortality of both HD and CKD groups was significantly shorter than that of the control group (log-rank P < 0.01 for both). There was no significant difference between RT and the control group (log-rank P = 0.053). (B) All groups were compared in terms of composite outcome (mortality or ICU admission). Median time to composite outcome was 24 days in the HD group, 21 days in the RT group, 20 days in the CKD group and 29 days in the control group. Mean survival durations of both the HD and CKD groups were statistically significantly shorter than that of the control group (log-rank P < 0.01 for both). There was no significant difference between RT and the control group (log-rank P = 0.052). (C) New matched groups created by PSM from the control and RT groups were compared. The median survival duration was >16 days in the matched RT group and >18 days in the matched control group. The mean survival duration of the matched RT group was similar to that of the matched control group (log-rank P = 0.37). (D) New matched groups created by PSM from HD and CKD groups were compared. Median survival duration was 25 days in the matched HD group and 22 days in the matched CKD group. Mean survival duration of the matched HD group was not significantly different from that of the matched CKD group (log-rank P = 0.21). (E) New matched groups created by PSM from CKD and RT groups were compared. Median survival duration was 23 days in the matched CKD group and >20 days in the matched RT group. Mean survival duration of the matched CKD group was not significantly different than that of the matched RT group (log-rank P = 0.077). (F) New matched groups created by PSM from CKD and control groups were compared. Median survival duration was 23 days in the matched CKD group and >24 days in the matched control group. Mean survival duration of the matched CKD group was significantly different from that of the matched control group (log-rank P < 0.001).