Background: Mortality rates in patients with chronic renal failure (CRF) are high both before and after start of renal replacement therapy (RRT). However, few studies of mortality and progression have been performed in an unselected CRF population.

Methods: We followed up a population-based inception cohort of 920 men and women aged 18 to 74 years who had CRF (serum creatinine level > 3.4 mg/dL [>300 μmol/L] for men and >2.8 mg/dL [>250 μmol/L] for women) for 55 to 79 months. Relationships between the outcomes (death and start of RRT) and independent variables under study (age, sex, primary renal disease, body mass index [BMI], and glomerular filtration rate [GFR] at entry) were explored by using Cox regression models.

Results: Seven hundred thirty-nine patients (80%) started RRT during the follow-up period. As expected, GFR at entry was clearly linked to the incidence of RRT (P < 0.0001). Age was related inversely to incidence of RRT (adjusted relative risk for patients ≥65 years relative to patients <45 years, 0.72; 95% confidence interval, 0.57 to 0.90). Men progressed to RRT more often than women (adjusted relative risk, 1.59; 95% confidence interval, 1.35 to 1.88). BMI was unrelated to RRT incidence. By the end of follow-up, 389 patients with CRF (42%) had died, 89 of them (10%) before the start of RRT. The most common primary cause of death was cardiovascular disease (37.5%). Characteristics significantly related to a greater mortality rate included older age, diagnoses of diabetic nephropathy and nephrosclerosis, and low BMI.

Conclusion: Preuremic characteristics (age, sex, primary renal diagnosis, BMI, and GFR) are predictive of prognosis in unselected patients with CRF.