Edmund G. Lowrie

Medical outcomes study short form-36: a consistent and powerful predictor of morbidity and mortality in dialysis patients

BACKGROUNDnOne of the guidelines released by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (K/DOQI) recommends that patients with glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 undergo regular assessment of functioning and well-being (FWB) to establish baselines, monitor changes in FWB over time, and assess the effect of interventions on FWB. Although this recommendation stresses the importance of assessing and monitoring physical and mental health functioning, the Medical Outcomes Study Short Form-36 (MOS SF-36) might also be useful for predicting crucial longer-term patient outcomes. This cross-sectional study tested the hypothesis that the Physical Component Summary (PCS) and Mental Component Summary (MCS) scales of the MOS SF-36 predict morbidity (measured as hospitalization) and mortality rates among dialysis patients.nnnMETHODSnData were collected from 13,952 prevalent dialysis patients served by Fresenius Medical Care North America including age, gender, race, diabetes, serum albumin, creatinine, bicarbonate, potassium, phosphorus, hemoglobin, iron, ferritin, white blood cell count, urea reduction ratio, serum glutamic oxaloacetic-transaminase, and systolic blood pressure. FWB was measured via the MOS SF-36 Summary scale scores, PCS, and MCS. Also collected was information about hospitalizations and patient mortality.nnnRESULTSnPCS and MCS were consistent predictors of hospitalizations and mortality rates even after adjustment for clinically relevant factors.nnnCONCLUSIONnBecause PCS and MCS are associated with hospitalization and mortality, administering this self-report measure may serve as a valuable supplement to clinical measures traditionally relied on to predict patient outcomes. Moreover, such information may be unavailable through any other single mechanism.

Quality-of-life evaluation using Short Form 36: Comparison in hemodialysis and peritoneal dialysis patients

Short Form 36 (SF-36) is a well-documented health-related quality-of-life (HRQOL) instrument consisting of 36 questions compressed into eight scales and two primary dimensions: the physical and mental component scores. This tool was used to evaluate QOL among peritoneal dialysis (PD) and hemodialysis (HD) patients. The results of 16,755 HD and 1,260 PD patients (728 continuous ambulatory PD [CAPD] and 532 continuous cycling PD [CCPD]) completing an SF-36 during 1996 were analyzed. Three analyses of variance were performed, consisting of (1) no adjustment, (2) case mix (age, sex, race, and diabetes), and (3) case mix plus laboratory parameters. PD patients were younger (P < 0.001), a larger fraction were white (P < 0.001), fewer had diabetes (P < 0.001), and had lower serum albumin concentrations (P < 0.001) and higher creatinine, hemoglobin, and white blood cell count values (P < 0.001) than HD patients. Diabetes was present in a larger fraction of CCPD than CAPD patients (P < 0.001). HD and PD patients scored similarly for scales reflecting physical processes. PD patients scored higher for mental processes, but only after statistical adjustment for the laboratory measures. Scores on scales reflecting physical processes were worse, and those reflecting mental processes were better among CCPD than CAPD patients. HD and CAPD scores were similar. CCPD patients perceived themselves as more physically impaired but better adjusted than HD or CAPD patients. These descriptive data show that perception of QOL among PD and HD patients is similar before adjustment, but PD patients score higher for mental processes with adjustment. CCPD patients score worse for physical function and better for mental function than either CAPD or HD patients. We cannot, however, exclude the influence of therapy selection.

Associates of mortality among peritoneal dialysis patients with special reference to peritoneal transport rates and solute clearance

The current report describes the distributions of selected demographic and biochemical parameters, clearance, and other transport values among patients undergoing peritoneal dialysis (PD) and evaluates the associates of mortality using those values, with and without clearance and peritoneal equilibration test (PET) data. All patients receiving PD on January 1, 1994 were selected (n = 2,686). Patients who switched to another form of dialysis during the study period were removed from the study at the time of therapy change. Working files were constructed from the clinical database to include demographic, laboratory, and outcome data. Laboratory data were available in only 1,603 patients and were used to evaluate the biochemical associates of mortality after merging the biochemical, demographic, and outcome data. Patients with clearance data or PET studies underwent a second analysis to assess the effects of peritoneal and renal clearance on survival. The analysis of demographic and laboratory data confirmed the importance of age and serum albumin concentration as predictors of death. Residual renal function (RRF) was strongly correlated with survival, but peritoneal clearance was not. Several possible explanations for the lack of correlation between peritoneal clearance and survival are discussed. The data suggest that RRF and peritoneal clearance may be separate and not equivalent quantities. Substantial work is required to confirm or refute these findings, because the information is essential to establish the adequate dose of PD in patients with various degrees of RRF.

Acute-phase inflammatory process contributes to malnutrition, anemia, and possibly other abnormalities in dialysis patients

The target organ failures associated with uremia are most often considered to be caused by processes other than uremia per se. Heart disease, for example, is considered the product of hypertension, lipid abnormalities, and so forth, rather then the uremic state. Erythropoietin deficiency, blood loss, and iron deficiency are believed to cause anemia, rather than the uremic state. Malnutrition is believed to be the product of poor nutrient intake and perhaps nutrient losses, rather than uremia per se. This article reviews evidence suggesting that anemia and malnutrition share a common cause; the acute-phase inflammatory process that is a normal host-defense mechanism. Given the high prevalence of heart disease among patients with end-stage renal disease (ESRD), data indicating activation of the acute-phase process in patients with kidney failure, and emerging evidence that the process has a significant role in the risk for cardiovascular disease among patients without kidney failure, there is a strong likelihood that heart disease will share with anemia and malnutrition the acute-phase state as a contributing cause. Thus, instead of disconnected target organ failures, each with different antecedent causes, we see emerging the likelihood of a unifying pathobiology for uremia. The antecedents of morbidity and mortality appear as a web of organ failures connected by a common pathobiology. Whereas each failure likely has contributing causes other than the acute-phase state, they probably share the state as a causative, contributing, or exacerbating factor.

Primary Associates of Mortality Among Dialysis Patients: Trends and Reassessment of Kt/V and Urea Reduction Ratio as Outcome-Based Measures of Dialysis Dose

Information from a large clinical database was used to construct time trends for the leading associates of mortality among dialysis patients. The changing strengths of association of those measures with mortal risk were also evaluated. Strength did not change in meaningful ways for serum albumin, creatinine, or anion gap concentrations. It declined for the urea reduction ratio (URR), however, as prevalent values of the URR increased. Irrational patterns of association between the URR and other measures suggested reevaluation of the urea kinetic method for prescribing and judging dialysis dose. Two premises on which the urea kinetic equations rest are not valid if the context for their use is clinical outcome instead of predicting blood urea nitrogen (BUN) concentration. Rigorous use of the Kt/V criterion for dialysis dose could lead to clinical judgment errors, particularly underdialysis for small or malnourished persons. Changes for prescribing dose and judging therapy are recommended.