Background: In the general population, hypertension is the leading cause of cardiovascular mortality. In dialysis patients, however, the relationship between blood pressure (BP) and mortality is controversial. We analyzed this relationship in hemodialysis (HD) patients.
Methods: The study population included 405 patients who had survived at least two years on HD. The observation period was initiated at the beginning of the third year. Predialysis BP measurements of all the dialysis treatments performed during the second year of HD was collected as the baseline data. Mean systolic BP (SBP) and mean diastolic BP (DBP) were calculated. Demographic and comorbidity data were collected at the start of the observation period (beginning of third year of HD). Mortality was analyzed at the end of the follow-up (death or December 31, 1998; total mortality), during the first two years of follow-up (years 3 and 4 of HD; early mortality) and after the second year of follow-up (> or = 5 years of HD; late mortality).
Results: In the multivariate analysis, SBP and DBP were significantly associated with death. The adjusted total mortalities were U shaped. When early mortality was analyzed, only low BP (DBP <74.5 mm Hg) was significantly associated with mortality. When late mortality was analyzed, only high BP (SBP> 160 mm Hg) was significantly associated with mortality. In the early deaths, a cardiac cause was significantly less frequent, while withdrawal and malignancy were more frequent than in late deaths.
Conclusions: This study confirms that hypertension is a risk factor for mortality in HD patients, and shows the importance of the length of the follow-up time to demonstrate this relationship. The low frequency of a cardiac cause in the early death group suggests that the association between hypotension and mortality in HD patients is not related to cardiovascular causes, and only reflects the association between hypotension and other severe medical conditions.