Background: Although conventional hemodialysis (CHD) is currently provided primarily on an intermittent basis for patients with end-stage renal diseases (ESRD), the value of daily dialysis is well documented. Daily hemofiltration (DHF) is a convective therapy that has received little attention as an alternative to CHD. The aim of this feasibility study was to validate and assess the efficacy of DHF (6 times/week) as an alternative to CHD (3 times/week) in patients with ESRD.
Methods: In this prospective single-arm open-labeled study, DHF was administered over 4 weeks after a 1-week run-in phase period of CHD. Blood samples were drawn at baseline and on a weekly basis during the trial, and ultrafiltrate samples were collected weekly during the DHF period. The primary endpoint was to achieve a daily spKt/V of 0.40 (equivalent to a weekly stdKt/V of approximately 2.0). To achieve this goal, the DHF prescription consisted of an exchange volume of 40% of total body water. Secondary endpoints were the evaluation of blood pressure and anemia parameters, nutritional and mineral metabolism markers and health-related quality of life measures.
Results: Twelve patients completed the study. Mean age was 54 years, two-thirds were men, and 83% had arteriovenous fistulae. DHF delivered a mean (+/-SD) spKt/V of 0.44 +/- 0.06. This goal was reached by delivering an exchange volume of 13-14 liters, consisting of a replacement fluid volume of 11.7 +/- 1.9 l/session and net fluid loss of 1.4 +/- 0.1 l/session. Conversion from CHD to DHF resulted in marked reduction in treatment time (3.8 vs. 2 h/session, p < 0.001) and net fluid loss (2.6 vs. 1.4 l/session, p < 0.001). Calculated weekly standard Kt/V during the last week of DHF was 1.9 +/- 0.2. DHF achieved a median beta2-microglobulin (beta2-M) removal of 170 mg/session, resulting in a decrease of mid-week pre-therapy beta2-M levels (48 +/- 34 vs. 36 +/- 25 mg/l, p = 0.07). Compared with CHD, DHF resulted in lower systolic (143 +/- 19 vs. 133 +/- 16 mm Hg, p = 0.002) and diastolic (79 +/- 11 vs. 72 +/- 12 mm Hg, p = 0.002) blood pressure, reduction in antihypertensive medications (2.1 +/- 0.7 vs. 1.1 +/- 0.8, p = 0.002), higher caloric intake (1,778 +/- 441 vs. 2,044 +/- 564 kcal/day, p = 0.01), higher normalized protein catabolic rate (0.88 +/- 0.17 vs. 1.00 +/- 0.35 g/kg/day, p = 0.05), higher pre-albumin levels (330 +/- 50 vs. 378 +/- 84 g/dl, p = 0.06), higher vitality (p = 0.02), improved cognitive function (p = 0.04) and less symptoms/problems (p = 0.03). Serum albumin and potassium levels remained unchanged but the serum bicarbonate level dropped during the 1-month period of DHF.
Conclusions: DHF (6 times/week) over a 1-month period achieved a weekly stdKt/V of approximately 2.0, which is similar to that recommended for 3 times weekly CHD, reduced beta2-M levels, lowered blood pressure, and had some beneficial effect on nutritional parameters, and health-related quality of life measures.