There may be cumulative 'metabolic scars' after a decade or more of long-term hemodialysis. We studied 39 patients who have been on maintenance hemodialysis for 10-24 years to determine their functional status and pathobiology. The 39 long-term (> or = 10 years) patients were compared with a control cohort of 37 age-, gender-, race-, and renal-diagnosis-matched patients on hemodialysis for < or = 3 years. The functional status was measured using a modified Karnofsky scale, and the employment status was noted as well. Details of hospitalizations and intercurrent infections requiring outpatient oral or intravenous antibiotic therapy during the preceding year were obtained. Comorbid medical conditions were documented, and basic laboratory tests were performed. The mean age of the long-term patients was 51.8 +/- (SE) 1.9 years, and the mean age of the control group was 51.5 +/- 2.4 years (p = 0.92). Three times weekly hemodialysis prescriptions were similar in both groups (long-term: 3.5 +/- 0.02 h, control: 3.4 +/- 0.02 h; p = 0.27). The mean modified Karnofsky scores were equivalent in both groups. The rate of hospitalization during the preceding year was higher among the long-term patients (0.92 +/- 0.19/patient year) than in the control patients (0.51 +/- 0.15/patient year; p = 0.09). The long-term patients had more intercurrent infections (1.23 +/- 0.21) than the controls (0.68 +/- 0.16; p = 0.04). (ABSTRACT TRUNCATED AT 250 WORDS)