Abstracts

Rationale: In our previous research, tractable epilepsy (ICD-9-CM: 345.X0) differed from intractable epilepsy (345.X1) (X includes digits 0-9) in hospitalization rates and associated procedures. In this study, we further examined if tractable and intractable epilepsy also differ with respect to comorbid diagnoses during hospitalizations. Methods: We extracted hospitalizations from HCUP data for any-listed tractable and intractable epilepsy during four time periods: 1998-2000, 2001-2003, 2004-2006, and 2009-2011 and excluded those before 1998 and in 2007 and 2008 to avoid possible effects of diagnostic code revisions in 1997 and 2006. We examined time periods to assess the stability of estimates. We screened and compared how often 262 groups of diagnoses (composed of multiple diagnostic codes) occurred as comorbidities in hospitalizations for the two epilepsies. We calculated the age-adjusted relative risk (RR) of the proportion of grouped diagnoses in those with tractable epilepsy to that in those with intractable epilepsy. We also compared the average number of diagnoses and the percentage of hospital deaths. Results: Thirty-four grouped diagnoses occurred often, over many time periods, and differed statistically significantly between hospitalizations for tractable and intractable epilepsy. Five grouped diagnoses directly affecting the central nervous system (2 infection groups, 1 cancer group, 2 disorder groups) occurred more often in hospitalizations for intractable epilepsy than in those for tractable epilepsy (RR < 1). The remaining 29 grouped diagnoses occurred more often in hospitalizations for tractable epilepsy than in those for intractable epilepsy (RR>1) and usually involved other parts of the body (the heart, the lung, the gastrointestinal tract), mental illnesses (mood disorders, anxiety, substance abuse), or infections. The average number of recorded diagnoses in hospitalizations for tractable epilepsy statistically significantly exceeded that for intractable epilepsy.. The percentage of deaths during hospitalizations for tractable epilepsy (range: 1.57% to 2.19%) also statistically significantly exceeded that for intractable epilepsy (range: 0.75% to 1.24%) across all the time periods. Conclusions: Compared to intractable epilepsy, those with tractable epilepsy had much higher risks for the most comorbid diseases, more recorded diagnoses, and higher hospital death rates. The results highlight the need to treat common chronic diseases that co-occur in patients with epilepsy to reduce hospitalizations and mortality. Funding: None.