Summary

Patients with kidney failure who are on dialysis often need treatment for anemia. In a new study, altitude was found to be a factor in how much hemoglobin they needed. Those living high up - beyond 6,000 feet - survived longer and needed less hemoglobin. This may be because there is less oxygen at high altitude and the body compensates by making more hemoglobin.

Introduction

Patients with end stage renal disease (ESRD) or kidney failure require dialysis to support the kidneys and with this comes a need for erythropoietin (EPO) to boost hemoglobin levels. Recent work has suggested that those with ESRD living at high altitude could achieve higher hemoglobin levels at lower doses than expected of EPO. High altitude means lowered oxygen levels - hypoxia - and the body adapts by producing more of the hemoglobin that carries oxygen through the circulation. In ESRD patients this could affect their anemia status and maybe even their survival prospects.

What was done

Researchers at Brigham and Women's Hospital and Harvard Medical School, Boston, studied a group of 804,812 patients who had initiated dialysis for ESRD and grouped them according to the altitude at which they lived. Most were at or around sea level (40.5 percent) or between 250 and 1,999 feet (54.4 percent). But 1.9 percent lived above 4,000 and 5,999 feet and 0.4 percent lived above 6,000 feet. The team collected mortality data for the group.

What was found

Compared to those living at sea level, the death rate was reduced by three percent for those living up to 1,999 feet and by seven per cent for those living from 2,000 to 3,999 feet. For the high altitude groups, death rate went down by 12 percent for those living between 4,000 and 5,999 feet and by 15 percent for those above 6,000 feet. Five year survival was 35 percent for those at sea level and 43 percent for those at high altitude.

What this study means

We already know that living at high altitude has a small benefit in terms of reduced mortality among the general population. The survival benefit seen here in the ESRD patients goes far beyond this. It looks at if hypoxia-inducible factors in terms of increased hemoglobin levels are particularly beneficial in this patient group.

Source

Altitude and all-cause mortality in incident dialysis patients
WC. Winkelmayer,  et al, Journal of the American Medical Association, February 4 2009, vol. 301, pp. 508--512