Predictors of Hospital Length and Cost of Stay in a National Sample of Adult Patients with Psychotic Disorders

In this analysis of national data, we found that the rate of admissions for patients with primary diagnoses of psychotic disorders was 175 per 100,000 U.S. population ages 18–64, with a range of 160–199 per 100,000 over the nine years (2003–2011) of the study. Substantial variability in rates of admissions, LOS, and COS was related to region of the country. Furthermore, race and ethnicity appeared to play a critical role in predicting both LOS and COS, as did other nonclinical characteristics.

The highest rate of admission for each study year was in the Northeast (overall mean rate of 242 per 100,000), and the lowest rate was generally in the West (overall mean rate of 140 per 100,000). Patients hospitalized in the Midwest, South, and West experienced shorter hospital stays than those hospitalized in the Northeast. The longer LOS and the higher COS in the Northeast were striking, particularly with the higher admission rate. These differences in use of inpatient care across the United States beg questions about the appropriateness of care and the use of scarce mental health resources (21).

Because many states in the Northeast, particularly New York and Massachusetts, have high rates of spending on both inpatient and outpatient care, our findings suggest that utilization rates are evidence not of a trade-off between use of outpatient and inpatient services but of relatively well-funded mental health systems. However, understanding how these geographic differences affect outcomes and determining whether use of inpatient or outpatient care leads to improved outcomes for identifiable subgroups of adults are important avenues for future research.

Racial-ethnic differences were noted in rates of admission as well as in LOS and COS. On average, African-American patients had 381 admissions per 100,000 race-adjusted population compared with 102 per 100,000 for white patients and 59 per 100,000 for Asian/Pacific Islander patients. Compared with LOS among white patients, LOS among African-American patients was a half-day shorter and COS was 4% lower. Conversely, LOS was one day longer among Asian/Pacific Islander patients compared with white patients, and COS was 10% higher than among white patients. These differences in LOS and COS have been well documented in other samples (22) and speak to an interplay of increased reliance on acute care for African Americans, accompanied by a lower per capita hospital resource allocation. It is possible that these findings are related to population differences in symptom expression between African Americans and other groups or bias in the interpretation of behavior (23). Results suggest that African Americans are admitted to inpatient facilities when admission is not clinically necessary or when their symptoms are less severe than whites, lending further support to findings that acute psychiatric services are overutilized for some African Americans who could potentially be better served in outpatient treatment (23–25). After the analysis adjusted for severity, our finding of differences in hospital care by race-ethnicity also reflects disparities in care, which is consistent with other findings (23,26). A better understanding of this dynamic could improve services by improving the cultural responsiveness of health care providers or by increasing the availability and acceptability of needed outpatient treatment (27,28).

Of note, we found that clinical severity was a driving force for both LOS and COS. The largest difference in LOS, almost two weeks, was found for those with extreme loss of functioning. The results also support a dose-response effect for loss of functioning, with each increase in functioning impairment associated with a longer hospital stay.

In addition, household income, as indicated by patients’ zip code, and primary payment source were significantly associated with LOS and COS. Individuals who lived in areas with lower incomes had shorter LOS and lower COS than those living in higher-income areas. It is difficult to believe that unmeasured severity of illness increases with household income; however, the mechanisms of this income-based disparity are unclear. A possible explanation for the disparity in LOS by household income and for the other findings is the well-documented shortage of psychiatric beds (4,29,30). These shortages may be differentially distributed across communities by income, and hospitals that serve lower-income areas may be forced to reduce LOS to increase access for those in need.

Not surprisingly, payer source was related to LOS and COS, which likely reflects differences in reimbursement rates, managed care efforts, and other payer characteristics. Patients who used Medicare or Medicaid had longer LOS and higher COS than patients who used private insurance. Unlike race-ethnicity or income, these mechanisms are better understood. Unmeasured severity is a likely explanation, because patients with the most severe schizophrenia are covered by public insurance rather than private insurance (31). Furthermore, even though legislation has increased parity in recent years, some evidence suggests that private insurers continue to restrict mental health services relative to general medical services (31). Also, patients hospitalized in private, nonprofit hospitals or in private, investor-owned hospitals experienced shorter LOS and higher COS than patients in government-owned hospitals, which is likely indicative of more patient turnover in private facilities.

Although the use of longitudinal NIS data over nine years was a strength of this study in assessing hospitalization rates and predictors of LOS and COS, the data were limited in that only a few patient and hospital characteristics were included in the NIS, which in turn limited the conclusions that can be drawn. The reliance on ICD-9-CM codes for both the sampling and the severity measures, without a clinical assessment for research purposes, has limitations related to the accuracy of the coding process. Evidence suggests that these codes are reliable for psychiatric diagnoses, but the evidence is limited (32). The NIS also captures events that occur only during hospitalization and does not provide information on readmissions. However, the differences found among patient-level characteristics suggest that use of inpatient clinical care plays a role in mental health disparities and warrants further investigation of the mechanisms by which patients’ demographic backgrounds have differential effects on care.

The authors thank Dan Ciccarone, M.D., M.P.H. (primary investigator, RO1DA037820), for support in funding data acquisition and for general encouragement.