Survival predictability of time-varying indicators of bone disease in maintenance hemodialysis patients.

Although renal osteodystrophy and vitamin D analogs may be related to survival in maintenance hemodialysis (MHD) patients, most studies have examined associations between baseline values and survival without accounting for variations in clinical and laboratory measures over time. We examined associations between survival and quarterly laboratory values and administered paricalcitol in a 2-year (July 2001-June 2003) cohort of 58,058 MHD patients from all DaVita dialysis clinics in USA using both time-dependent Cox models with repeated measures and fixed-covariate Cox models with only baseline values. Whereas hypercalcemia and hyperphosphatemia were robust predictors of higher death risk in all models, the association between serum calcium and mortality was different in time-varying models. Changes in baseline calcium and phosphorus values beyond the Kidney Disease Outcome Quality Initiative recommended targets were associated with increased mortality. Associations between high serum parathyroid hormone and increased death risk were masked by case-mix characteristics of MHD patients. Time-varying serum alkaline phosphatase had an incremental association with mortality. Administration of any dose of paricalcitol was associated with improved survival in time-varying models. Controlling for nutritional markers may introduce overadjustment bias owing to their strong collinearity with osteodystrophy surrogates. Whereas both time-dependent and fixed-covariate Cox models result in similar associations between osteodystrophy indicators and survival, subtle but potentially clinically relevant differences between the two models exist, probably because fixed models do not account for variations of osteodystrophy indices and changes in medication dose over time.

HEMO equilibrated Kt/V goals are difficult to achieve in large male patients.

The long-term outcome of chronic hemodialysis patients is influenced by the adequacy of dialysis treatment. A major objective of the ongoing US HEMO Study is to determine if a higher target value of treatment as measured by the equilibrated Kt/V (eKt/V), a calculation of dialysis adequacy developed for the study, of 1.45 results in a better outcome than the presently accepted target value for eKt/V of 1.05 (approximately equal to spKt/V of 1.2). eKt/V corrects for urea rebound and gives a better estimate of actual treatment received. To examine the feasibility of achieving the higher eKt/V in large hemodialysis patients, a retrospective analysis of 389 monthly eKt/V values from 65 men on chronic hemodialysis of larger than average size dialyzed at high blood and dialysate flows (QB 400, QD 800 ml/min) with large dialyzers (1.8-2.2 m2) for longer than 4 hours three times weekly was performed. A total of 278 treatments considered optimal by a blood water urea clearance estimate were included in the final analyses. The mean body weight and Chertow water volume were 84.3+/-16.5 kgm and 50.0+/-6.7 L, respectively. The mean sp Kt/V was 1.29+/-0.17. The mean eKt/V was 1.16+/-0.14 and was inversely correlated with weight and water volume (p < 0.0001). Despite the large dialyzers and high blood and dialysate flow rates, no patient weighing more than 80 kgm or with body water volume exceeding 46 liters achieved an eKt/V of 1.45. This study suggests that creative dialyses will be required to achieve the HEMO "high arm" target in large patients.

Young children who drown in hot tubs, spas, and whirlpools in California: a 26-year survey.

A survey of drownings in hot tubs, spas, and whirlpools in California 1960-85 suggests a person- and site-specific profile. The identified 74 deaths occurred mostly in White children, under two years of age, in Southern California, during the late afternoons, from May through August. From 1967 to 1985, the drowning rate increased tenfold. The deaths were associated with access to the water, lack of supervision, neuromotor handicaps, and entrapment by suction. Educational and environmental control efforts are required to reduce the incidence.