Receipt of outpatient follow-up care after hospitalization for a mental disorder is a recognized mental health service quality indicator (
1,
2). The National Committee on Quality Assurance (NCQA) has endorsed quality indicators for follow-up 30 and seven days after hospitalization for mental illness. Yet, rather than resting on empirical research, the rationale for these quality indicators rests primarily on the clinically intuitive concept that individuals whose mental disorders are sufficiently severe to warrant inpatient treatment benefit from timely follow-up with outpatient mental health care. Surprisingly few studies have examined the clinical benefits of continuing outpatient mental health care after hospital discharge (
3–
6).
Hospital readmission has been used as a measure of the effectiveness of mental health services. An analysis of administrative data of privately insured psychiatric inpatients showed that patients with follow-up outpatient visits within a year of hospital discharge were readmitted to the hospital approximately half as often as those without follow-up visits (
5). However, because this analysis did not control for potentially confounding patient characteristics, the difference in readmission risk may have reflected a tendency for higher-risk patients not to receive outpatient treatment after hospital discharge. A Department of Veterans Affairs analysis of psychiatric inpatients with co-occurring substance use disorders that adjusted for several potentially confounding patient characteristics found that continuing psychiatric treatment within 30 days of hospital discharge was not related to risk of hospital readmission in the 90 days postdischarge (
6). A controlled study of privately insured patients who were assigned to receive usual, enhanced, or intensive-case-management discharge planning after hospital discharge also reported no significant group differences in hospital readmission at 60 and 180 days following discharge (
7).
In light of the paucity of research supporting an association between follow-up outpatient care and subsequent hospital readmission, we examined this issue in large populations of privately insured and Medicaid-insured psychiatric inpatients. To reduce the clinical heterogeneity of the study cohorts, we limited the study to adult inpatients with first-listed diagnoses of either schizophrenia or bipolar disorder, and we performed separate analyses of each diagnostic group.
To better understand risk factors for not receiving outpatient care within 30 days of hospital discharge, we also examined proportions of patients who did and did not receive such follow-up care stratified by demographic and clinical characteristics. Prior research indicates that about half of Medicaid inpatients with psychiatric disorders receive outpatient mental health care during the 30 days after hospital discharge (
8). Although several patient characteristics have been associated with not receiving outpatient treatment after psychiatric hospitalization (
7,
9–
11), little is known about whether risk factors for not receiving follow-up care vary across major psychiatric diagnostic groups (
12).
Methods
Data Sources
The analyses used Truven MarketScan Commercial (2010–2014) and Medicaid (2010–2013) databases. The project was exempted from human subjects review by the New York State Psychiatric Institute’s Institutional Review Board.
Sample Selection
For the analysis of mental health outpatient visits within 30 days of hospital discharge, which was based on an NCQA HEDIS measure, patients were 18 to 64 years of age, had inpatient admissions of one to 30 days, had a primary discharge diagnosis of schizophrenia (ICD-9-CM code 295) or bipolar disorder (codes 296.0–296.1 and 296.4–296.8), were discharged home, and were enrolled in a health plan during the 120 days preceding admission and the 30 days following hospital discharge. For the analysis of hospital readmission in the 31–120 days following hospital discharge, patients were enrolled for 120 days after the index hospital discharge. Patients readmitted to the hospital within 30 days after the index hospital discharge were removed from the analysis. Patients entered the study cohort on the earliest date of meeting study eligibility criteria, and no patient contributed more than one episode. Separate analyses were performed for the schizophrenia and bipolar cohorts.
Independent Variables
Patient characteristics included age, sex, and payment source (commercial insurance or Medicaid). Information on race-ethnicity (black, white, Hispanic, and other) was available for Medicaid-insured patients. As in prior research (
9), length of inpatient stay was partitioned by days into short (one to eight days), medium (nine to 12 days), and long (13 to 30 days). During the 120-day period before the index hospital admission, patients were classified by presence or absence of claims for a substance use disorder (
ICD-9-CM codes 291–292 and 303–305). Also during this period, patients were classified by whether they had an inpatient or an emergency department visit with a first-listed mental disorder diagnosis and a visit to a mental health provider. On the basis of hospital discharge diagnoses, patients with schizophrenia were subclassified as having schizoaffective disorder (
ICD-9-CM code 295.7) or other schizophrenic disorders (codes 295.0–295.6 and 295.8–295.9), and those with bipolar disorder were subclassified as depressed (codes 296.5 and 296.50–296.56), manic (codes 296.01–296.06, 296.4, and 296.40–46), mixed (codes 296.6 and 296.61–296.66), or other (codes 296.7, 296.80, and 296.89).
Other Covariates
Other covariates in the logistic regressions included a prescription for an antipsychotic, antidepressant, anxiolytic, mood stabilizer, or stimulant medication during the 120 days prior to hospital admission. Patients were also assigned Elixhauser comorbidity scores based on the number of treated comorbid general medical conditions in the 120-day preadmission period (
13), excluding depression, psychosis, and substance use disorders. Patients were further classified as having a claim for depression (
ICD-9-CM codes 296.2, 296.3, 296.9, 300.4, and 311) or an anxiety disorder (codes 300.0, 300.2, 300.3, 304, and 308.3) during the 120 days prior to hospital admission.
Dependent Variables
In the analysis of postdischarge follow-up, visits were defined based on HEDIS specifications for follow-up mental health visits during the first 30 days after the index hospital discharge (
2). For the psychiatric hospital readmission analyses, readmissions were defined as inpatient episodes with first-listed diagnoses of mental disorders (
ICD-9-CM codes 290–319) during the 90 days (days 31–120 after hospital discharge) after the first 30 days following the index hospital discharge. In a post hoc analysis of follow-up visits after the first seven days following hospital discharge, mental health readmission was considered during the eight to 97 days following hospital discharge.
Statistical Analysis
Demographic and health care service use characteristics of patients with and without mental health follow-up outpatient visits within 30 days were compared by using Wald chi-square tests. Rates of mental health follow-up outpatient visits within 30 days were calculated overall and stratified by each independent variable. Wald chi-square tests were used to test for differences in the rates across strata. Logistic regression models were used to examine associations between patient characteristics and receipt of a mental health follow-up outpatient visit within 30 days, controlling for sex, age, payer type, length of index admission, diagnostic subtype, comorbid mental disorders, use of mental health services, psychotropic medications, and Elixhauser score.
The proportion of patients who had a readmission in the 31- to 120-day period postdischarge was compared between groups who did and did not have a mental health follow-up outpatient visit within 30 days of discharge. Wald chi-square tests were conducted for the overall sample and stratified by patient characteristics. A series of logistic regression models was used to calculate associations between receipt of a 30-day mental health follow-up outpatient visit and hospital readmission overall and within each stratum, controlling for demographic and service use factors. We also conducted the 30-day outpatient follow-up analysis and 31- to 120-day readmission analysis by race-ethnicity in the Medicaid subsample. To assess the generalizability of the results, we performed corresponding analyses of the association between follow-up visits within seven days of discharge and hospital readmission within eight to 97 days of discharge.
Discussion
After the analyses accounted for several potentially confounding patient characteristics, patients with schizophrenia or bipolar disorder who received outpatient mental health care in the first month after hospital discharge had slightly lower odds of psychiatric hospital readmission during the following three months. These associations support a focus on improving the transition from inpatient to outpatient care (
14).
A tendency for patients who received follow-up visits in the 30 days after hospital discharge to have a lower risk of subsequent readmission was prominent among patients with schizophrenia who had not received any mental health care in the 120 days prior to the admission, a group with an especially low rate of outpatient follow-up care. For these patients, follow-up mental health treatment appeared to be important in lowering the likelihood of readmission. Among patients with bipolar disorder, follow-up care was associated with a lower risk of readmission for patients who were older, who were admitted for a manic episode, and who had a mental health emergency department visit in the preadmission period. For these patients, the first postdischarge outpatient mental health visit may help consolidate a process of recovery that was initiated during the inpatient stay. In manic episodes, there is a high risk of treatment nonadherence (
15) and symptom exacerbation after treatment discontinuation (
16). Clinical instability may increase the importance of continuing care after hospital discharge.
In accord with prior research (
6,
17), longer inpatient stays were correlated with receipt of mental health follow-up outpatient visits within 30 days of hospital discharge for both diagnostic groups. Longer inpatient stays may permit more time for stabilization of clinical symptoms and may improve discharge planning. These patients may also have more severe conditions that increase the likelihood that they will be seen within 30 days of hospital discharge. Because the length of psychiatric hospital admissions has declined over the past several years (
18), clinical staff involved in transition management may have less time to assist patients and their families with discharge planning.
In both diagnostic groups, a significant association between outpatient follow-up visits and short-term risk of hospital readmission occurred among commercially insured patients but not among Medicaid-insured patients. Variations in clinical presentation, patient resources, discharge readiness, or the effectiveness of available outpatient services may contribute to this difference. In other clinical contexts, Medicaid-insured psychiatric patients have been found to receive less intensive care than their commercially insured counterparts (
19).
A corresponding significant inverse association was not observed between outpatient follow-up visits within seven days of discharge and subsequent hospital readmission. The reasons for the differences between the seven-day and 30-day analyses are unclear but may be related to differences in factors that govern readmissions during the two following time periods. By design, the analysis of outpatient visits within the first 30 days excluded patients who were readmitted within the first 30 days, whereas the seven-day analysis excluded a narrower group who were readmitted within the first seven days. Readmissions that follow quickly after hospital discharge may be more closely related to clinical readiness for discharge or the quality of discharge planning. In the general medical literature, factors such as living alone (
20), low patient satisfaction with the inpatient physician (
21), and not having a regular physician (
22) have been associated with hospital readmission within 30 days of discharge.
Consistent with previous research (
3,
11,
12), receiving mental health care in the months before hospital admission was the strongest predictor of outpatient mental health treatment continuity following hospital discharge. For patients with schizophrenia or bipolar disorder, established treatment routines may influence future treatment-seeking behavior. Among patients without existing outpatient treatment relationships, difficulties building new treatment relationships (
23), long wait times for first appointments (
24), stigma, and negative symptoms may complicate completion of outpatient mental health referrals. For high-risk patients, assertive discharge planning, engagement of family members, and shared decision making may facilitate new treatment contacts and coordinate the care transition (
25).
Roughly a quarter of the inpatients with schizophrenia and bipolar disorder had received treatment for a substance use disorder during the 120-day period prior to their inpatient admission. After the analyses controlled for several patient characteristics, these patients were about one-third less likely than their counterparts without a comorbid substance use disorder to receive outpatient follow-up care within 30 days. Co-occurring substance use disorders among inpatients with other mental illnesses have previously been linked to lower odds of follow-up after psychiatric hospital discharge (
12). In community practice, treatment for comorbid substance use disorders is not always offered, and when offered it is not always accepted. Among patients with schizophrenia or bipolar disorder, the strength of the associations between follow-up visits and risk of hospital readmission did not markedly vary by the presence of a comorbid substance use disorder.
In the Medicaid sample of patients with schizophrenia or bipolar disorder, white patients were more likely than black patients to receive follow-up outpatient care. This pattern is consistent with prior work with diagnostically mixed samples (
8) and with a broad tendency for African Americans with severe mental illnesses to receive lower-quality care (
26). There is a critical need to develop interventions that not only improve continuity of care but that narrow racial-ethnic disparities (
14).
This study had several potential limitations. First, data were not available concerning many factors that may influence continuing care or the benefits of this care. For example, we were not able to measure inpatient staff preparation of patients for their first outpatient visit or availability of outpatient services (
27) nor were we able to assess associations of outpatient visits with symptoms. Second, diagnoses were based on clinician judgment. Third, analyses were limited to nonelderly adult Medicaid and commercially insured patients with schizophrenia or bipolar disorder and may not generalize to uninsured populations (
28), elderly patients, or those with other diagnoses. Fourth, because this exploratory study was based on a large number of observations, even modest associations of uncertain clinical and policy significance may be statistically significant. Fifth, our primary focus on outpatient follow-up within 30 days of discharge and hospital readmission over the subsequent 90 days excluded the substantial number of patients with hospital readmissions within the first 30 days of hospital discharge. Finally, residual confounding may have accounted for the tendency for patients who received continuing care to have lower odds of psychiatric hospital readmission.