Co-existence of Hypertension and Pre-existing Cardiovascular Disease and Mortality in Patients on Continuous Ambulatory Peritoneal Dialysis

Background Little is known about whether co-existence of hypertension (HTN) and pre-existing cardiovascular disease (CVD) has a more harmful effect on mortality compared with either comorbidity alone in patients on continuous ambulatory peritoneal dialysis (CAPD). Methods We conducted a retrospective study of 3073 incident Chinese patients on CAPD from five dialysis centers between January 1, 2005 and December 31, 2018 in a real-world setting. The primary and secondary outcomes were all-cause and CVD mortality. The association between interesting comorbidities and mortality was analyzed using Cox regression models and the Fine and Gray competing risk models. Results Over a median of 33.7 months of follow-up, 581 (18.6%) patients died, with 286 (9.3%) CVD mortality. The incidence of all-cause mortality was 32.2, 56.1, 74.4, and 131.0/1000 patient-years, and the incidence of CVD mortality was 15.0, 28.2, 34.7, and 69.6/1000 patient-years in the control group (those without either hypertension or CVD), HTN group, CVD group, and HTN plus CVD group respectively. After adjusting for the confounding factors, HTN plus CVD, CVD, and HTN groups had a higher risk of all-cause mortality (HR 3.98, 95% CI 3.07 to 5.17; HR 2.18, 95% CI 1.27 to 3.74; and HR 1.83, 95% CI 1.47 to 2.28) and CVD mortality (HR 4.68, 95% CI 3.27 to 6.69; HR 2.11, 95% CI 0.96 to 4.63; and HR 1.87, 95% CI 1.37 to 2.54), respectively, compared to the control group. Similar findings were observed using the Fine and Gray competing risk models. There was no significant interaction between HTN and CVD on all-cause and CVD mortality (β = 0.010, P = 0.973; β = 0.058, P = 0.892) in the study population. Conclusions Among CAPD patients, co-existence of HTN and pre-existing CVD at the start of CAPD had a more harmful effect on mortality compared to either HTN or pre-existing CVD alone, and pre-existing CVD may have also a more harmful effect on mortality than HTN.