Clinical Research: Effect of altitude on mortality of end-stage kidney disease patients ongoing hemodialysis in Peru

Name: Katia Marisa Bravo-Jaimes, M.D.

Hospital / Affiliation: Universidad Peruana Cayetano Heredia / Research Associate University of Rochester Medical Center / Internal Medicine Resident

Home Country: Peru

Host Country: Peru

Year: 2011

Status of your program: IN PROGRESS

Title of the project: 

Effect of altitude on mortality of end-stage kidney disease patients ongoing hemodialysis in Peru

Topic: 

Chonic Kidney Disease, Hemodialysis 

Short description of the project or abstract:

BACKGROUND: Chronic kidney disease is a public health problem around the world. In Latin America, the prevalence of end-stage kidney disease (ESKD) patients has tremendously risen during the last decade. Previous studies have suggested that receiving dialysis at high altitude confers mortality benefits; however this effect has not been proved above 2000 meters or in developing countries.

METHODS: This historical cohort study analized medical records from six hemodialysis centers of the Peruvian Social Security System. The selected centers were located at 44, 150, 1894, 2335, 3400 and 3827 meters above the sea level (masl). Adult ESKD patients who started hemodialysis between January 1, 2000 and December 31, 2010 were included. Patients were classifed into two strata based on the elevation above the sea level of their city of residence: < 2000 masl and > 2000 masl. Demographic characteristics and cause of ESKD were recorded at first hemodialysis. The outcome variable was death from any cause, which was collected from national registries. Cox proportional hazards models were built for the time from first dialysis to death from any cause, stratifying by year and censoring patients by December 31, 2013; at 5 years after first dialysis; loss to follow-up; transference to another hemodialysis center out of the city; renal transplantation or migration to peritoneal dialysis during follow-up. Those who lived at 44 and 150 masl served as the reference category for all statistical analysis. A p-value <0.05 was considered statistically significant. RESULTS: 723 patients were enrolled. Women represented 38.2% of the sample (n=248). The mean age was 52.8 ±16.9 years. The group of > 2000 masl was composed of 166 patients (22%). The 5-year all-cause mortality rate was 81 per 1000 person-years. There was a dual but not significant effect in survival according to altitude. In first years after follow-up, survival rates were lower in the group > 2000 masl, however after 8 years of follow-up this trend reversed (p=0.091). Age at first hemodialysis and gender were not significantly associated to mortality at altitude levels > 2000 masl. Only patients with diabetes as cause of ESKD had higher mortality rates at > 2000 masl [HR 2.7 (CI 95% 1.4-5.3), p=0.003]. This association was independent of age at first hemodialysis.

CONCLUSIONS: In Peru, patients receiving hemodialysis at high altitude do not experience mortality benefits. In fact, diabetics experience higher mortality rates at > 2000 masl.

Learning or Research objectives:

To determine the effect of altitude on mortality of end-stage renal disease patients receiving hemodialysis in Peru.