Association Between Quality Measures and Mortality in Individuals With Co-Occurring Mental Health and Substance Use Disorders

Abstract

Importance: Individuals with co-occurring mental and substance use disorders have increased rates of mortality relative to the general population. The relationship between measures of treatment quality and mortality for these individuals is unknown.

Objective: To examine the association between 5 quality measures and 12- and 24-month mortality.

Design, setting and participants: Retrospective cohort study of patients with co-occurring mental illness (schizophrenia, bipolar disorder, post-traumatic stress disorder and major depression) and substance use disorders who received care for these disorders paid for by the Veterans Administration between October 2006 and September 2007. Logistic regression models were used to examine the association between 12 and 24-month mortality and 5 patient-level quality measures, while risk-adjusting for patient characteristics. Quality measures included receipt of psychosocial treatment, receipt of psychotherapy, treatment initiation and engagement, and a measure of continuity of care. We also examined the relationship between number of diagnosis-related outpatient visits and mortality, and conducted sensitivity analyses to examine the robustness of our findings to an unobserved confounder.

Main outcomes measure: Mortality 12 and 24 months after the end of the observation period.

Results: All measures except for treatment engagement at 24 months were significantly associated with lower mortality at both 12 and 24 months. At 12 months, receiving any psychosocial treatment was associated with a 21% decrease in mortality; psychotherapy, a 22% decrease; treatment initiation, a 15% decrease, treatment engagement, a 31% decrease; and quarterly, diagnosis-related visits a 28% decrease. Increasing numbers of visits were associated with decreasing mortality. Sensitivity analyses indicated that the difference in the prevalence of an unobserved confounder would have to be unrealistically large given the observed data, or there would need to be a large effect of an unobserved confounder, to render these findings non-significant.

Conclusions and relevance: This is the first study to show an association between process-based quality measures and mortality in patients with co-occurring mental and substance use disorders, and provides initial support for the predictive validity of the measures. By devising strategies to improve performance on these measures, health care systems may be able to decrease the mortality of this vulnerable population.

Keywords: Co-occurring disorders; Mental health services; Mortality; Quality measures; Quality of care; Veterans.

Figure 1

Mortality associated with receiving the care assessed by each quality measure at 12 and 24 months

Figure 2

Association between number of diagnosis-related visits and 12-month mortality for veterans with co-occurring mental and substance use disorders, FY2007–FY2008

Figure 3. Sensitivity analysis of the potential impact of an unobserved confounder, U, on significant associations of the quality measure and mortality

Areas with no shading remained significant for selected OR(U) values. Shaded areas represent combinations of P1, P0, and OR(U) that would result in a loss of significance of the QM-mortality association. Dark gray: OR(U)=2.58, middle gray: OR(U)=1.43, light gray: OR(U)=1.27.