Gender-specific differences in dialysis quality (Kt/V):: 'big men' are at risk of inadequate haemodialysis treatment

Background. Inadequate dialysis dose is closely related to mortality and morbidity of maintenance haemodialysis (MHD) patients. According to the DOQI guidelines a minimum prescribed dialysis dose of single-pool Kt/V (Kt/V-sp) = 1.3, equivalent to equilibrated double pool Kt/V (e-Kt/V-dp) = 1.1, is recommended. Knowledge of patient-related risk factors for inadequate delivery of haemodialysis would be helpful to select patient subgroups for intensive control of dialysis adequacy. Methods. A retrospective survey was conducted to assess the prevalence of inadequate dialysis dose according to DOQI criteria during a 7-month period. A total of 320 e-Kt/V-dp measurements in 62 MHD patients were evaluated (mean effective dialysis time 222 +/- 32 min). Residual renal function (RRF) was expressed as renal weekly Kt/V (r-Kt/V-week) and included into assessment of total weekly renal and dialytic Kt/V (t-Kt/V-week). Results. Inadequacy (e-Kt/V-dp < 1.10) was prevalent in 37.2% of all measurements and in 22/62 patients (35.5%). In 54% of underdialysed patients r-Kt/V-week compensated for insufficient dialytic urea removal. Mean weekly Kt/V was inadequate (t-Kt/V-week < 3.30) in 12/62 patients (19.4%) of whom 91.7% (11/12) were male. Body-weight, urea distribution volume (UDV), and body-surface area (BSA) were significantly higher in inadequately vs adequately dialysed males. UDV > 42.0 litres or BSA > 2.0 m(2) and a lack of RRF (r-Kt/V-week < 0.3) put 'big men' at increased risk to receive an inadequate dose of dialysis. Conclusion. Our data identify patients at risk for inadequate haemodialysis treatment. Special attention should be focused on 'big men' with UDV > 42.0 litres or BSA > 2.0 m(2). In this subset of patients frequent measurements of t-Kt/V-week and assessment of RRF should be mandatory.