Association of the Kidney Failure Risk Equation With High Health Care Costs.

Introduction: The Kidney Failure Risk Equations (KFRE) are accurate and validated to predict the risk of kidney failure in individuals with chronic kidney disease (CKD), but their potential to predict health care costs in the US health care system is unknown. We assessed the association of kidney failure risk from the 4-variable and 8-variable 2-year KFRE models with monthly health care costs in US patients with CKD stages G3 and G4. Methods: This was an ancillary study to a larger observational, retrospective cohort study examining the association between serum bicarbonate and adverse kidney outcomes. Monthly medical costs were calculated from individual health care insurance claims. Generalized linear regression models were used to examine the association of KFRE score with health care costs. Results: A total of 1721 patients qualified for the study (1475 and 246 with CKD stages G3 and G4, respectively). For 8-variable KFRE, each 1% (absolute) increase in risk was associated with 13.5% (P < 0.001) and 4.1% (P < 0.001) higher monthly costs for patients with CKD stage G3 and G4, respectively. For 4-variable KFRE, a 1% increase in risk was associated with 6.7% (P = 0.016) and 2.9% (P= 0.014) increase in monthly costs for patients with CKD stage G3 and G4, respectively. Conclusion: Higher risks of kidney failure as predicted by the 4-variable or 8-variable KFRE were associated with higher 2-year medical costs for patients with CKD stages G3 and G4. The KFRE may be a useful tool to anticipate medical costs and target cost-reducing interventions for patients at risk of kidney failure.

Metabolic Acidosis and Adverse Outcomes and Costs in CKD: An Observational Cohort Study.

Rationale & Objective: Metabolic acidosis is a risk factor for progression of chronic kidney disease (CKD), but little is known about its effect on health care costs and resource utilization. We describe the associations between metabolic acidosis, adverse kidney outcomes, and health care costs in patients with CKD stages G3-G5 and not receiving dialysis. Study Design: Retrospective cohort study. Setting & Participants: An integrated claims-clinical data set of US patients with CKD stages G3-G5, with serum bicarbonate values of 12 to <22 mEq/L (metabolic acidosis group) or 22 to 29 mEq/L (normal serum bicarbonate level group). Predictor: The primary exposure variable was the baseline serum bicarbonate level. Outcomes: The primary clinical outcome was the composite of all-cause mortality, maintenance dialysis, kidney transplant, or a decline in the estimated glomerular filtration rate of ≥40% (DD40). The primary cost outcome was all-cause predicted per-patient per-year cost, assessed over a 2-year outcome period. Analytical Approach: Logistic and generalized linear regression models, adjusted for key covariates such as age, sex, race, kidney function, comorbidities, and pharmacy insurance coverage, were used to assess serum bicarbonate levels as a predictor of DD40 and health care costs, respectively. Results: 51,558 patients qualified. The metabolic acidosis group experienced higher rates of DD40 (48.3% vs. 16.7%, P < 0.001) and higher all-cause yearly costs ($65,172 vs. $24,681, P < 0.001). Two-year adjusted odds ratio of DD40 per 1-mEq/L increase in serum bicarbonate levels was 0.873 (95% CI, 0.866-0.879); the parameter estimate (±SE) for costs was -0.070 ± 0.0075 (P < 0.001). Limitations: Possible residual confounding. Conclusions: Patients with CKD and metabolic acidosis had higher costs and rates of adverse kidney outcomes compared with patients with normal serum bicarbonate levels. Each 1-mEq/L increase in serum bicarbonate levels was associated with a 13% decrease in 2-year DD40 events and a 7% decrease in per-patient per-year cost.

Assessment of the Potential for Veverimer Drug-Drug Interactions.

Veverimer is a polymer being developed as a potential treatment of metabolic acidosis in patients with chronic kidney disease. Veverimer selectively binds and removes hydrochloric acid from the gastrointestinal tract, resulting in an increase in serum bicarbonate. Veverimer is not systemically absorbed, so potential drug-drug interactions (DDIs) are limited to effects on the absorption of other oral drugs through binding to veverimer in the gastrointestinal tract or increases in gastric pH caused by veverimer binding to hydrochloric acid. In in vitro binding experiments using a panel of 16 test drugs, no positively charged, neutral, or zwitterionic drugs bound to veverimer. Three negatively charged drugs (furosemide, aspirin, ethacrynic acid) bound to veverimer; however, this binding was reduced or eliminated in the presence of normal physiologic concentrations (100-170 mM) of chloride. Veverimer increased gastric pH in vivo by 1.5-3 pH units. This pH elevation peaked within 1 hour and had returned to baseline after 1.5-3 hours. Omeprazole did not alter the effect of veverimer on gastric pH. The clinical relevance of in vitro binding and the transient increase in gastric pH was evaluated in human DDI studies using two drugs with the most binding to veverimer (furosemide, aspirin) and two additional drugs with pH-dependent solubility effecting absorption (dabigatran, warfarin). None of the four drugs showed clinically meaningful DDI with veverimer in human studies. Based on the physicochemical characteristics of veverimer and results from in vitro and human studies, veverimer is unlikely to have significant DDIs. SIGNIFICANCE STATEMENT: Patients with chronic kidney disease, who are usually on many drugs, are vulnerable to drug-drug interactions (DDIs). The potential for DDIs with veverimer was evaluated based on the known site of action and physicochemical structure of the polymer, which restricts the compound to the gastrointestinal tract. Based on the findings from in vitro and human studies, we conclude that veverimer is unlikely to have clinically significant DDIs.

A longitudinal study of uremic pruritus in hemodialysis patients.

BACKGROUND AND OBJECTIVES: Although uremic pruritus (UP) is a highly prevalent complication of chronic kidney disease, it remains poorly characterized. There have been no longitudinal studies of natural history, and no health-related quality of life (HR-QOL) instruments have been developed for UP. The objectives of this study were to describe the natural history of UP, to compare rating scales of itching intensity, and to assess usefulness and validity of HR-QOL instruments for UP. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The intensity, severity, and effects of pathologic itching on HR-QOL were assessed prospectively in 103 patients with UP on chronic hemodialysis. Outcome measures were obtained at scheduled intervals over 3.5 months. RESULTS: Itching daily or nearly daily was reported by 84% of patients and had been ongoing for >1 year in 59%. In 83%, pruritus involved large, nondermatomal areas with striking bilateral symmetry. Two thirds of the patients were using medications such as antihistamines, steroids, and various emollients without satisfactory relief of itching. Statistically significant associations were found among itching intensity, severity, and HR-QOL measures in domains such as mood, social relations, and sleep. Among patients with moderate-to-severe UP, changes in itching intensity of 20% or greater were associated with significant reductions in HR-QOL measures. CONCLUSIONS: This first longitudinal study of UP describes key features of UP and its effect on HR-QOL. The assessment instruments we have developed are easily used, are responsive to changes in UP intensity, and should facilitate clinical evaluation and research to meet the needs of afflicted patients.

Participation in the decision to become vaccinated against human papillomavirus by California high school girls and the predictors of vaccine status.

BACKGROUND: State and national policymakers are actively debating the merits of legally mandating the human papillomavirus (HPV) vaccine. METHODS: This was a cross-sectional pilot study designed to identify factors associated with HPV vaccination in 170 high school girls and the decision making by girls about vaccination. RESULTS: Overall, 48.4% participated in the vaccination decision making and 37.8% were vaccinated, but there were significant vaccine-related knowledge gaps. Girls often lacked basic knowledge necessary to make vaccine decisions. Vaccination was significantly associated with older age, vaccine information sources, and higher vaccine-related knowledge, but not with estimates of risk of HPV-related diseases, religion, or frequency of health care visits. CONCLUSIONS: This paper describes the first study to have identified factors associated with HPV vaccination among California high school girls and to have documented that a high percentage are participating in the vaccination decision making. These findings have implications for adolescent health education and nursing practice and provide new information relevant to the current public policy debates about mandatory vaccination.