Mental illness and length of inpatient stay for Medicaid recipients with AIDS

Health Services Research, Oct, 2004 by Donald R. Hoover, Usha Sambamoorthi, James T. Walkup, Stephen Crystal

In order to understand more fully the associations (and potential causal patterns) between psychiatric illness and length of stay, we analyzed 24,675 hospital visits among 6,497 patients diagnosed with AIDS and hospitalized at least once from 1992 to 1998. To account for potential confounding conditions, we considered a large number of covariates. Because type of mental illness may be important, we separately considered schizophrenia, bipolar illness, and major depression (which are believed to be more severe mental illnesses [Schirmar, Rothbard, Kanter, andJung 1990]) from other mental illnesses. To better understand the relative impact of an acute mental illness diagnosis associated with the hospital stay as opposed to a history of mental illness, we separately compared visits for which mental illness was an acute (i.e., the primary or a secondary) diagnosis and those where there was no acute mental illness, but the patient had an identified history of mental illness (i.e., at other visits).

METHODS

Study Population

The patient population for this study was derived from file matching between New Jersey Medicaid eligibility files and the State's AIDS Registry through March 1996 under a cooperative agreement with the New Jersey Department of Health and Senior Services and Division of Medical Assistance and Health Services. This article includes 6,247 adult (18 years or older) Medicaid recipients identified through the match who were diagnosed with AIDS in New Jersey by March 1996 and hospitalized at least once after that diagnosis from 1992 to 1998.

Measures

Length of Stay and Time to Readmission Outcomes. Length of Stay (LOS) was the number of days from the date of admission to the date of discharge. Because "one day hospitalizations" are usually clinic visits, they were excluded from the analyses (but the findings are essentially unaltered with one day hospitalizations included). For patients readmitted to a hospital on the same day as discharged (or transferred to another hospital), the two visits were combined. Time to Readmission (TR) was calculated as number of days from the date of discharge from a visit to the date of admission for a subsequent visit.

Mental and Neurological Illness. The following International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9) codes were considered to indicate mental illness: 295--Schizophrenic Disorders, 296--Affective Psychoses, 297--Paranoid States, 298--Other Nonorganic Psychoses, 300--Neurotic Disorders, 301--Personality Disorders, 302--Sexual Disorders, 306--Psychophysiologic Disorders, 307--Special Mental Symptoms Not Elsewhere Classified, 308--Acute Reaction to Stress, 309--Adjustment Reaction, 310--Nonpsychotic Brain Syndrome, 311--Depressive Disorder Not Elsewhere Classified, 372--Conduct Disturbance Not Elsewhere Classified, 313--Emotional Disorders of Adolescence, 314--Hyperkinetic Syndrome, 316--Psychic Factors with Other Disorders, and 780--Alterations of Consciousness. We are limited to diagnoses available in the Medicaid dataset; patients diagnosed with mental illnesses elsewhere were not identified.