Review and analysis of hospitalization costs associated with antipsychotic nonadherence in the treatment of schizophrenia in the United States

OBJECTIVE: To review the literature addressing the economic outcomes of nonadherence in the treatment of schizophrenia, and to utilize the review results to provide an update on the economic impact of hospitalizations among schizophrenia patients related to antipsychotic nonadherence. METHODS: A structured search of EMBASE, Ovid MEDLINE, PubMed and PsycINFO for years 1995-2007 was conducted to identify published English-language articles addressing the economic impact of antipsychotic nonadherence in schizophrenia. The following key words were used in the search: compliance, noncompliance, adherence, nonadherence, relapse, economic, cost, and schizophrenia. A bibliographic search of retrieved articles was performed to identify additional studies. For a study to be included, the date of publication had to be from 1/1/1995 to 6/1/2007, and the impact of nonadherence had to be measured in terms of direct healthcare costs or inpatient days. Subsequently, an estimate of incremental hospitalization costs related to antipsychotic non adherence was extrapolated at the US national level based on the reviewed studies (nonadherence rate and hospitalization rate) and the National Inpatient Sample of Healthcare Cost and Utilization Project (average daily hospitalization costs). RESULTS: Seven studies were identified and reviewed based on the study design, measurement of medication nonadherence, study setting, and cost outcome results. Despite the varied adherence measures across studies, all articles reviewed showed that antipsychotic nonadherence was related to an increase in hospitalization rate, hospital days or hospital costs. We also estimated that the national rehospitalization costs related to antipsychotic nonadherence was 1479 million, ranging from 1392 million to 1826 million in the US in 2005. LIMITATIONS: The estimate of rehospitalization costs was restricted to schizophrenia patients from the Medicaid program. Additionally, the studies we reviewed did not capture the newer antipsychotic drugs (ziprasidone, aripiprazole and paliperidone). Thus, the nonadherence rates or rehospitalization rates might have changed after these new drugs came to the market, which could limit our cost estimation. CONCLUSIONS: Poor adherence to antipsychotic medications was consistently associated with higher risk of relapse and rehospitalization and higher hospitalization costs. To reduce the cost of hospitalizations among schizophrenia patients, it seems clear that efforts to increase medication adherence should be undertaken.