July 4, 2018

Increased Risk of Hospital Admission for ICD-9-CM Psychotic Episodes Following Admission for Epilepsy

SIGNIFICANCE: An epilepsy admission was independently associated with subsequent hospital readmission for psychotic episodes, even after adjustment for confounding variables.

OBJECTIVE: To determine whether epilepsy admissions are associated with a higher readmission risk for psychotic episodes compared to admissions for other medical causes.

METHODS: The Nationwide Readmissions Database is a nationally representative dataset from 2013. We used International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes to identify medical conditions. There were 58 278 index admissions for epilepsy, and this group was compared against admissions for stroke (n = 215 821) and common medical causes (pneumonia, urinary tract infection [UTI], congestive heart failure [CHF], and chronic obstructive pulmonary disease [COPD], n = 973 078). Readmission rates for psychotic episodes within 90 days from discharge for index hospitalizations were calculated. Cox regression was used to test for associations between admission type and re-admission for psychotic episodes up to 1 year after index admission, in univariate models and adjusted for multiple medical, social, and psychiatric variables.

RESULTS: Up to 90 days from index admission, there were 683/100 000 readmissions for psychotic episodes in the epilepsy group, 92/100 000 in the stroke group, and 58-206/100 000 in the medical group. The relative rate of readmission in the epilepsy group was highest in the first 30 days following index admission (311/100 000). Unadjusted hazard ratio (HR) for readmission for psychotic episodes within 1 year in the epilepsy group compared to the stroke group was 6.58 (95% confidence interval [CI] 5.69-7.61, P < 2 × 10-16 ), and 4.41 compared to the medical group (95% CI 4.00-4.85, P < 2 × 10-16 ). The fully adjusted HR for readmission in the epilepsy group remained elevated at 3.63 compared to the stroke group (95% CI 3.08-4.28, P < 2 × 10-16 ), and 1.95 compared to the medical group (95% CI 1.76-2.15, P < 2 × 10-16). Confounding factors most strongly associated with psychosis readmission were documented psychosis history at the time of index admission, younger age, and lower income quartile.

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