Identification of volume overload hospitalizations among hemodialysis patients using administrative claims: a validation study

Abstract

BackgroundHigh rates of volume overload hospitalizations may indicate inadequate dialysis facility fluid management. Administrative claims databases are often used to study such outcomes, but these data are generated for billing purposes and may not capture clinical nuance. It is unknown if volume overload admissions can be correctly identified in administrative data and if a single claims-based definition for volume overload can be used across epidemiologic surveillance studies, observational studies of exposure-outcome associations and quality assessments. We conducted a validation study to assess the accuracy of claims-based definitions for volume overload hospitalizations among hemodialysis patients.MethodsData were taken from a random sample of 315 adult hemodialysis patients admitted to University of North Carolina Hospitals from January 2010 through June 2013. Standardized chart reviews were conducted to clinically adjudicate the presence or absence of volume overload at hospital admission. Claims-based definitions were constructed from varying combinations of fluid-related ICD-9 discharge diagnosis codes including fluid overload, pulmonary edema, pleural effusion, and heart failure. Using clinically adjudicated volume overload hospitalizations as the reference standard, validity metrics and their 95 % confidence intervals (CIs) were estimated for each definition.ResultsOf the 315 hospital admissions, 77 (24.4 %) were clinically adjudicated as volume overload hospitalizations. The prevalence of claims-identified volume overload admissions varied across definitions, ranging from 1.6 to 37.1 %. When definitions were constructed with discharge diagnosis codes present in any billing position, volume overload hospitalizations defined by fluid overload, pleural effusion or heart failure diagnosis codes had the highest sensitivity, 81.8 % (95 % CI: 71.4 %, 89.7 %). Volume overload hospitalizations defined by pulmonary edema diagnosis codes had the highest specificity, 98.3 % (95 % CI: 95.8 %, 99.5 %). Definitions constructed with discharge diagnosis codes present in any billing position (versus the primary position) captured more false positive events.ConclusionsPrevalence and validity estimates of volume overload hospitalizations vary across claims-based definitions. A universal claims-based definition for volume overload hospitalizations may not apply to all clinical and research scenarios. Investigators and regulators need to consider the implications of misclassifying events when evaluating and monitoring hemodialysis patient volume overload admissions with administrative data. Claims-based definitions should be selected accordingly.Electronic supplementary materialThe online version of this article (doi:10.1186/s12882-016-0384-6) contains supplementary material, which is available to authorized users.

Intradialytic Hypertension Frequency and Short-Term Clinical Outcomes Among Individuals Receiving Maintenance Hemodialysis

“…14 Volume-related hospitalizations were identified using a previously validated claims-based definition. 19 Supplementary Table 1 displays detailed outcome definitions.…”

Decreasing hospitalizations in patients on hemodialysis: Time for a paradigm shift

“…Fluid overload masked as heart failure is the most common reason for emergency department (ED) visits in the United States and Canada . Among US claims used for fluid‐related ESRD hospitalizations, heart failure was the primary diagnosis in 83% of episodes, fluid overload in 11%, and pulmonary edema in 6%; the average cost was $6372 per episode …”

“…EDW prescriptions often remain static despite changes in patients’ nutritional status, intake, and hospitalization status. Furthermore, because of coding constraints, symptoms related to fluid overload or chronic volume overload are categorized as cardiovascular disease . This leads to referral of patients to cardiology teams for long‐term management of patients, many of whom underappreciate the role of the dialysis prescription on cardiovascular outcomes …”

“…Fluid-related hospital admissions comprise the bulk of the high cardiovascular hospitalization rate in the hemodialysis population with annual costs totaling 250 million per year. 3,6,18,[37][38][39][40][41] Worldwide, the rate of hospitalization for fluid overload is 13.7 per 100 person-years in patients on hemodialysis and continues to increase, while in the United States the rate of cardiovascular hospitalizations, with a large portion related to fluid overload, is 40 per 100 person-year (accounting for close to 25% of hospitalizations) with a risk of 30-day rehospitalization of 37.7%. 3,28,39,42 Fluid overload masked as heart failure is the most common reason for emergency department (ED) visits in the United States and Canada.…”

“…3,28 Among US claims used for fluidrelated ESRD hospitalizations, heart failure was the primary diagnosis in 83% of episodes, fluid overload in 11%, and pulmonary edema in 6%; the average cost was $6372 per episode. 37 Patients on hemodialysis have a unique physiology because they are less able to regulate the body's fluid status with secondary effects on blood pressure. [43][44][45][46][47] Physiologists attribute the control of intravascular volume and resultant blood pressure to the kidneys, 48 This is particularly relevant in patients with ESRD since fluid status is a major determinant of their blood pressure and left ventricular load.…”