Long-term survival rates in haemodialysis patients treated with strict volume control

Abstract

Methods: We analysed the survival of 218 patients (132 male, 86 female, age 48 +/- 15 years) who were treated in our dialysis units since we adopted the strategy of strict volume control without antihypertensive drugs. The mean observation period was 47 +/- 34 (6-140) months. Follow-up was ended because of death (57 patients), transfer to another center (35 patients), continous ambulatory peritoneal dialysis (CAPD) (15 patients) or transplantation (23 patients), while 88 were still under our treatment at the time of writing.

Results: Blood pressure (BP) decreased from a mean of 150 +/- 31/89 +/- 16 at the start to 121 +/- 14/75 +/- 8 mmHg at the end of observation (P < 0.001). Only nine patients needed a drug (enalapril) to reach this goal. Cardiothoracic index (CTI) dropped from 0.50 +/- 0.06 to 0.46 +/- 0.05 (P < 0.001). Interdialytic weight gain decreased from 1440 +/- 360 to 930 +/- 240 g/day (P < 0.001). Mortality rate was 68, 2 per 1000 patient-years, better than in most published series. There was a striking influence of age, but also of CTI and systolic BP on survival rate. Patients with CTI > or = 0.48 showed mortality 3.8 times higher than CTI < 0.48 (log rank P < 0.001). Consequently, the mean CTI of the deceased patients was much higher (0.50) than the average of the group (0.46) while their mean BP (123 +/- 16/75 +/- 9 mmHg) was not significantly different from the other patients. We found no increased mortality at low-normal pressure levels (systolic BP between 100 and 130 mmHg), but mortality was increased in small groups of patients whose pressures were lower or higher than these values. Thus, the curve, relating mortality to blood pressure was shifted markedly to the left.

Conclusions: These results strongly suggest that the strategy of 'volume control', also when applied with conventional dialysis times, normalizes BP and increases survival of dialysis patients. Cardiomegaly, as evidenced on the chest X-ray despite normal BP, had a strong negative influence on survival. The large majority of the patients had low-normal BP after long periods of treatment and showed the lowest mortality, favouring the view that target BP should be lower than advised by most authors.