%0 Journal Article %J BMC Health Serv Res %D 2010 %T Defining emergency department episodes by severity and intensity: A 15-year study of Medicare beneficiaries. %A Kaskie, Brian %A Maksym Obrizan %A Elizabeth A Cook %A Michael P Jones %A Li Liu %A Suzanne E Bentler %A Robert B Wallace %A John F Geweke %A Kara B Wright %A Elizabeth A Chrischilles %A Claire E Pavlik %A Robert L. Ohsfeldt %A Gary E Rosenthal %A Frederic D Wolinsky %K Aged %K Aged, 80 and over %K Cohort Studies %K Emergency Service, Hospital %K Humans %K Insurance Claim Review %K Medicare %K Prospective Studies %K Severity of Illness Index %K United States %X

BACKGROUND: Episodes of Emergency Department (ED) service use among older adults previously have not been constructed, or evaluated as multi-dimensional phenomena. In this study, we constructed episodes of ED service use among a cohort of older adults over a 15-year observation period, measured the episodes by severity and intensity, and compared these measures in predicting subsequent hospitalization.

METHODS: We conducted a secondary analysis of the prospective cohort study entitled the Survey on Assets and Health Dynamics among the Oldest Old (AHEAD). Baseline (1993) data on 5,511 self-respondents >or=70 years old were linked to their Medicare claims for 1991-2005. Claims then were organized into episodes of ED care according to Medicare guidelines. The severity of ED episodes was measured with a modified-NYU algorithm using ICD9-CM diagnoses, and the intensity of the episodes was measured using CPT codes. Measures were evaluated against subsequent hospitalization to estimate comparative predictive validity.

RESULTS: Over 15 years, three-fourths (4,171) of the 5,511 AHEAD participants had at least 1 ED episode, with a mean of 4.5 episodes. Cross-classification indicated the modified-NYU severity measure and the CPT-based intensity measure captured different aspects of ED episodes (kappa = 0.18). While both measures were significant independent predictors of hospital admission from ED episodes, the CPT measure had substantially higher predictive validity than the modified-NYU measure (AORs 5.70 vs. 3.31; p < .001).

CONCLUSIONS: We demonstrated an innovative approach for how claims data can be used to construct episodes of ED care among a sample of older adults. We also determined that the modified-NYU measure of severity and the CPT measure of intensity tap different aspects of ED episodes, and that both measures were predictive of subsequent hospitalization.

%B BMC Health Serv Res %I 8 %V 10 %P 173 %8 2010 Jun 21 %G eng %1 http://www.ncbi.nlm.nih.gov/pubmed/20565949?dopt=Abstract %2 PMC2903585 %4 HOSPITALIZATION/emergency department service use/emergency department service use/medicare/predictive validity/predictive validity %$ 25020 %R 10.1186/1472-6963-10-173