Atrial fibrillation: the beat is faster than the answers.

The prevalence of atrial fibrillation is much greater among persons with end-stage renal disease (ESRD) than among the general population. While significant advances have been made recently in the treatment of atrial fibrillation in the general population, we know very little about the treatment of atrial fibrillation among those with ESRD. This Commentary explores gaps in our knowledge of how to treat this vulnerable and sick population.

Assessing the economic attractiveness of coronary artery revascularization in chronic kidney disease patients.

Chronic kidney disease (CKD) is associated with increased morbidity and mortality in coronary artery disease (CAD) patients. We compared the economic attractiveness of CAD revascularization procedures in patients with and without CKD. Our population included 6218 patients with significant CAD undergoing cardiac catheterization at Duke University between 1996 and 2001, with follow-up through 2002. We investigated the influence of CKD (creatinine clearance < 60 mL/min) upon 3-year survival and medical costs in our CAD population. Coronary artery bypass graft (CABG) surgery was an economically attractive alternative vs. percutaneous coronary intervention (PCI) or medical therapy for all patients with left main disease, three-vessel CAD patients without CKD, and two-vessel CAD patients with CKD. Medical therapy was an economically attractive strategy vs. CABG surgery or PCI for three-vessel CAD patients with CKD, two-vessel CAD patients without CKD, and all single-vessel CAD patients.

Do income level and race influence survival in patients receiving hemodialysis?

BACKGROUND: Residence in a lower-income area has been associated with higher mortality among patients receiving dialysis. We sought to determine whether these differences persist and whether the effect of income-area on mortality is different for African Americans versus patients of other races. METHODS: We evaluated relationships between lower- and higher-income versus middle-income area residence and mortality to 5 years after adjusting for differences in baseline clinical, dialysis facility, and socioeconomic characteristics in 186,424 adult patients with end-stage renal disease initiating hemodialysis at stand-alone facilities between 1996 and 1999. We also compared mortality differences between race and income level groups using non-African Americans residing in middle-income areas as the reference group. RESULTS: Patients with end-stage renal disease who reside in lower-income areas were younger and more frequently African American. After adjustment, there were no mortality differences among income level groups. However, African Americans in all income level groups had lower adjusted mortality compared with the reference group (lower-income hazard ratio [HR]=0.771, 95% confidence interval [CI], 0.736-0.808; middle-income HR=0.755, 95% CI, 0.730-0.781; higher-income HR=0.809, 95% CI, 0.764-0.857), whereas adjusted mortality was similar among non-African-American income level groups (lower-income HR=1.019, 95% CI, 0.976-1.064; higher-income HR=1.003, 95% CI, 0.968-1.039). CONCLUSION: Adjusted survival for patients receiving hemodialysis in all income areas was similar. However, this result masks the paradoxically higher survival for African American versus patients of other race and demonstrates the need to adjust for differences in demographic, clinical, provider, and socioeconomic status characteristics.

Sensitivity of International Classification of Diseases codes for hyponatremia among commercially insured outpatients in the United States.

BACKGROUND: Administrative claims are a rich source of information for epidemiological and health services research; however, the ability to accurately capture specific diseases or complications using claims data has been debated. In this study, the authors examined the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for the identification of hyponatremia in an outpatient managed care population. METHODS: We analyzed outpatient laboratory and professional claims for patients aged 18 years and older in the National Managed Care Benchmark Database from Integrated Healthcare Information Services. We obtained all claims for outpatient serum sodium laboratory tests performed in 2004 and 2005, and all outpatient professional claims with a primary or secondary ICD-9-CM diagnosis code of hyponatremia (276.1). RESULTS: A total of 40,668 outpatient serum sodium laboratory results were identified as hyponatremic (serum sodium < 136 mmol/L). The sensitivity of ICD-9-CM codes for hyponatremia in outpatient professional claims within 15 days before or after the laboratory date was 3.5%. Even for severe cases (serum sodium < or = 125 mmol/L), sensitivity was < 30%. Specificity was > 99% for all cutoff points. CONCLUSION: ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.

Medical costs of abnormal serum sodium levels.

An abnormal serum sodium level is the most common electrolyte disorder in the United States and can have a significant impact on morbidity and mortality. The direct medical costs of abnormal serum sodium levels are not well understood. The impact of hyponatremia and hypernatremia on 6-mo and 1-yr direct medical costs was examined by analyzing data from the Integrated HealthCare Information Services National Managed Care Benchmark Database. During the period analyzed, there were 1274 patients (0.8%) with hyponatremia (serum sodium <135 mmol/L), 162,829 (97.3%) with normal serum sodium levels, and 3196 (1.9%) with hypernatremia (>145 mmol/L). Controlling for age, sex, region, and comorbidities, hyponatremia was a significant independent predictor of costs at 6 mo (41.2% increase in costs; 95% confidence interval, 30.3% to 53.0%) and at 1 yr (45.7% increase; 95% confidence interval, 34.2% to 58.2%). Costs associated with hypernatremia were not significantly different from those incurred by patients with normal serum sodium. In conclusion, hyponatremia is a significant independent predictor of 6-mo and 1-yr direct medical costs.

Relationship between clinical outcomes and vascular access type among hemodialysis patients with Staphylococcus aureus bacteremia.

The association between hemodialysis vascular access type, costs, and outcome of Staphylococcus aureus bacteremia (SAB) among patients with ESRD remains incompletely characterized. This study was undertaken to compare resource utilization, costs, and clinical outcomes among SAB-infected patients with ESRD by hemodialysis access type. Adjusted comparisons of costs and outcomes were based on multivariable linear regression and multivariable logistic regression models, respectively. A total of 143 hospitalized hemodialysis-dependent patients had SAB at Duke University Medical Center between July 1996 and August 2001. A total of 111 (77.6%) patients were hospitalized as a result of suspected bacteremia; 32 (22.4%) were hospitalized for other reasons. Of the 111 patients, 59.5% (n = 66) had catheters as their primary access type, 36% (n = 40) had arteriovenous (AV) grafts, and 4.5% (n = 5) had AV fistulas. Patients with fistulas were excluded from analyses because of small numbers. Patients with catheters were more likely to be white, had shorter dialysis vintage, and had higher Acute Physiology and Chronic Health Evaluation II scores compared with patients with grafts. Unadjusted 12-wk mortality did not significantly differ between patients with catheters compared with patients with grafts (22.7 versus 10.0%; P = 0.098); neither did 12-wk costs differ by access type ($22,944 +/- 18,278 versus $23,969 +/- 13,731, catheter versus graft; P > 0.05). In adjusted analyses, there was no difference in 12-wk mortality (odds ratio 1.63; 95% confidence interval 0.29 to 9.02; catheter versus graft) or 12-wk costs (means ratio 0.84; 95% confidence interval 0.60 to 1.17; catheter versus graft) among SAB-infected patients with ESRD on the basis of hemodialysis access type. Twelve-week mortality and costs that are associated with an episode of SAB are high in hemodialysis patients, regardless of vascular access type. Efforts should focus on the prevention of SAB in this high-risk group.

Clinical outcomes and costs due to Staphylococcus aureus bacteremia among patients receiving long-term hemodialysis.

OBJECTIVE: To examine the clinical outcomes and costs associated with Staphylococcus aureus bacteremia among hemodialysis-dependent patients. DESIGN: Prospectively identified cohort study. SETTING: A tertiary-care university medical center in North Carolina. PATIENTS: Two hundred ten hemodialysis-dependent adults with end-stage renal disease hospitalized with S. aureus bacteremia. RESULTS: The majority of the patients (117; 55.7%) underwent dialysis via tunneled catheters, and 29.5% (62) underwent dialysis via synthetic arteriovenous fistulas. Vascular access was the suspected source of bacteremia in 185 patients (88.1%). Complications occurred in 31.0% (65), and the overall 12-week mortality rate was 19.0% (40). The mean cost of treating S. aureus bacteremia, including readmissions and outpatient costs, was $24,034 per episode. The mean initial hospitalization cost was significantly greater for patients with complicated versus uncomplicated S. aureus bacteremia ($32,462 vs $17,011; P = .002). CONCLUSION: Interventions to decrease the rate of S. aureus bacteremia are needed in this high-risk, hemodialysis-dependent population.

Costs and outcomes among hemodialysis-dependent patients with methicillin-resistant or methicillin-susceptible Staphylococcus aureus bacteremia.

OBJECTIVE: Comorbid conditions have complicated previous analyses of the consequences of methicillin resistance for costs and outcomes of Staphylococcus aureus bacteremia. We compared costs and outcomes of methicillin resistance in patients with S. aureus bacteremia and a single chronic condition. DESIGN, SETTING, AND PATIENTS: We conducted a prospective cohort study of hemodialysis-dependent patients with end-stage renal disease and S. aureus bacteremia hospitalized between July 1996 and August 2001. We used propensity scores to reduce bias when comparing patients with methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus bacteremia. Outcome measures were resource use, direct medical costs, and clinical outcomes at 12 weeks after initial hospitalization. RESULTS: Fifty-four patients (37.8%) had MRSA and 89 patients (62.2%) had MSSA. Compared with patients with MSSA bacteremia, patients with MRSA bacteremia were more likely to have acquired the infection while hospitalized for another condition (27.8% vs 12.4%; P = .02). To attribute all inpatient costs to S. aureus bacteremia, we limited the analysis to 105 patients admitted for suspected S. aureus bacteremia from a community setting. Adjusted costs were higher for MRSA bacteremia for the initial hospitalization (21,251 dollars vs 13,978 dollars; P = .012) and after 12 weeks (25,518 dollars vs 17,354 dollars; P = .015). At 12 weeks, patients with MRSA bacteremia were more likely to die (adjusted odds ratio, 5.4; 95% confidence interval, 1.5 to 18.7) than were patients with MSSA bacteremia. CONCLUSIONS: Community-dwelling, hemodialysis-dependent patients hospitalized with MRSA bacteremia face a higher mortality risk, longer hospital stays, and higher inpatient costs than do patients with MSSA bacteremia.