Simulated Effects of Policies to Reduce Diabetes Risk Among Adults With Schizophrenia Receiving Antipsychotics

Published in: Psychiatric Services [Epub Sep 2017]. doi:10.1176/appi.ps.201500485

Posted on RAND.org on September 28, 2017

by Andrew W. Mulcahy, Sharon-Lise T. Normand, John W. Newcomer, Benjamin Colaiaco, Julie M Donohue, Judith Lave, Emmett B. Keeler, Mark J. Sorbero, Marcela Horvitz-Lennon

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Research Questions

  1. Would policies designed to increase metabolic testing rates among Medicaid patients who are taking antipsychotic medication have the intended effect of reducing diabetes in this population?
  2. How would these policies affect health care costs?

Objective

Second-generation antipsychotics increase the risk of diabetes and other metabolic conditions among individuals with schizophrenia. Although metabolic testing is recommended to reduce this risk, low testing rates have prompted concerns about negative health consequences and downstream medical costs. This study simulated the effect of increasing metabolic testing rates on ten-year prevalence rates of prediabetes and diabetes (diabetes conditions) and their associated health care costs.

Methods

A microsimulation model (N=21,491 beneficiaries) with a ten-year time horizon was used to quantify the impacts of policies that increased annual testing rates in a Medicaid population with schizophrenia. Data sources included California Medicaid data, National Health and Nutrition Examination Survey data, and the literature. In the model, metabolic testing increased diagnosis of diabetes conditions and diagnosis prompted prescribers to switch patients to lower-risk antipsychotics. Key inputs included observed diagnoses, prescribing rates, annual testing rates, imputed rates of undiagnosed diabetes conditions, and literature-based estimates of policy effectiveness.

Results

Compared with 2009 annual testing rates, ten-year outcomes for policies that achieved universal testing reduced exposure to higher-risk antipsychotics by 14%, time to diabetes diagnosis by 57%, and diabetes prevalence by .6%. These policies were associated with higher spending because of testing and earlier treatment.

Conclusions

The model showed that policies promoting metabolic testing provided an effective approach to improve the safety of second-generation antipsychotic prescribing in a Medicaid population with schizophrenia; however, the policies led to additional costs at ten years. Simulation studies are a useful source of information on the potential impacts of these policies.

Key Findings

  • Policies to encourage metabolic testing could speed the diagnosis and reduce the rate of diabetes over ten years.
  • Diabetes prevalence, in this microsimulation model, would be reduced by less than 1 percent, but this reduction could have important implications clinically and economically.
  • Cost savings from preventing diabetes progression would need to be weighed against increased short-term costs related to treatment and policy implementation.

Recommendation

When issuing medication to treat schizophrenia, prescribers should consider the medium- and long-term costs of treatment in addition to safety concerns.

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