Behavioral and biochemical indices of compliance in hemodialysis patients

Noncompliance has been implicated in modifying morbidity and mortality in end stage renal disease patients; however, the data are conflicting, and measurement of compliance has been difficult. Traditional measurements of compliance include serum potassium (K) and phosphorus (P) concentrations, and interdialytic fluctuations in weight gain (IWG). This study correlated three indices: 1) Adequacy of dialysis (Kt/V); 2) protein ingestion (PCR); and 3) the percentage of time dialyzed compared with the total dialysis time prescribed (% Time) with the traditional measurements of compliance. Correlations were calculated among pre- and post-BUN (blood urea nitrogen), Kt/V, K and P, PCR, IWG, and % Time. As expected, BUN levels correlated with Kt/V, K, P, PCR, IWG, and % Time. Protein ingestion correlated with K and IWG, but not with % Time. Adequacy of dialysis correlated with P levels, but not with PCR, WG, or % Time. Phosphorus correlated with pre- and post-BUN, Kt/V, and % Time, but not with K. Potassium, P, and IWG did not correlate internally. The authors conclude that standard biochemical measures of compliance reflect different compliance behaviors (dietary selection and restriction, restriction of fluid and salt intake, and adherence to medication regimens). Percent time may be a powerful, independent measure of patient compliance with the dialysis regimen.