Beyond thrice-weekly hemodialysis

The frequency, length, and dose of hemodialysis (HD) have empirically evolved during the past four decades. The relationships among these variables and their influence on clinical outcomes are complex. Despite the lack of controlled studies and the selection bias inherent to cohorts studied with enhanced or intensified HD prescriptions, this review explores the impact of frequency, length, and dose of HD on clinical outcomes. The experiences with frequent HD make a formidable case for frequent therapies. The data show that quotidian regimens are associated with the best biochemical profiles, volume and hypertension control, and nutritional status, but do not provide the evidence for superior survival when compared to long nocturnal thrice-weekly or every-other-day conventional HD. The correlation between frequency and clinical outcomes seems evident, but not likely to be linear. Perhaps the greatest benefits are achieved from the simple avoidance of 48 hr without dialysis. Considering the additional cost and patient involvement with daily dialysis compared to every-other-day dialysis, it is logical to include the latter in future controlled studies on the benefits of frequent HD.