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

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In the adjusted model for LOS of visits with Primary Acute SMI versus its baseline category (visits from persons with no mental illness history) the upper entry in the second column of Table 2 is 1.32 (1.21, 1.44). This means that if all other characteristics in Table 2 are the same (i.e., age at diagnosis, severity of HIV disease, and so on), then LOS for a visit with a Primary Acute SMI diagnosis tends to be ~132 percent as long as the LOS of a visit from a person with no history of mental illness, with a 95 percent confidence limit of 121-144 percent as long. The change from 1.05 (~105 percent as long) in the unadjusted model to 1.32 (132 percent as long) in the adjusted model reflects adjustment for the fact that visits with Primary Acute SMI tend to be from persons with less severe AIDS conditions, younger persons, and having other characteristics that are independently associated with shorter LOS (data not shown). For most variables, the unadjusted ratios for LOS and TR in Table 2 are similar to the patterns reflected by mean LOS and TR in Table 1, so we focus on adjusted ratios. Minor differences between the patterns of Table 1 and unadjusted ratios of Table 2 can occur since mathematically means of log-transformed variables do not necessarily correspond ordinally to means of untransformed variables.

After adjusting for other variables in Table 2 (including access to health care and severity of HIV disease measures), person-visits with Primary SMI diagnoses had stays that were 32 percent longer (95 percent CI: 1.21-1.44) and those with Secondary SMI diagnoses had stays that were 11 percent longer (95 percent CI: 1.00-1.21) than did similar visits from persons with no identified history of mental illness. But adjusted length of stay for visits with an acute OMI diagnosis or for visits with no mental illness diagnosed from persons with SMI history or OMI history did not significantly differ from LOS for visits of persons with no mental illness history. As noted in the Methods section, associations for Primary and Secondary OMI did not differ. While HIV Dementia diagnosis was associated with longer adjusted LOS, ratio = 1.31 (95 percent CI: 1.13-1.52), this adjusted increase was less than that for diagnoses of other AIDS illnesses 1.42 (95 percent CI: 1.38-1.46).

In adjusted models, Time to Readmission (TR) ranged from being 2 percent to 16 percent shorter for each of the mental illness categories considered (Primary SMI, Secondary SMI, SMI History, Acute OMI, and OMI History) compared to visits of persons with no mental illness history. These differences were significant at p<0.001 for SMI history and Acute OMI and at p<0.05 for OMI History.

Almost all of the non-mental-health variables considered here remained significantly (and often very strongly) associated with LOS and/or TR in the adjusted models of Table 2. Indicators of more severe HIV disease (i.e., death in hospital) or worse underlying health of patient (i.e., older age) were associated with longer LOS and shorter TR in adjusted models. Medicare enrollment was associated with a TR almost two times longer; and from 1993 to 1998 (versus 1992), LOS systematically reduced to a ratio of 0.75 while TR ratio increased to 3.39, all significant at (p<0.001) in adjusted models. Those diagnosed with Primary and Secondary Substance Abuse each (versus those not diagnosed with Substance Abuse) had shorter adjusted LOS (ratios 0.57, [95 percent CI: 0.54-0.60] and 0.87 [95 percent CI: 0.84-0.90], respectively) and longer times to readmission (ratios 1.49 [95 percent CI: 1.34-1.66) and 1.17 [95 percent CI: 1.11-1.24], respectively).