Abstract
BackgroundReducing hospitalizations and emergency room visits is important to improve patient outcomes. This observational study examined the association between adherence to antipsychotics and risk of hospitalizations and emergency room (ER) visits among patients with bipolar disorder.MethodsClaims data from commercial healthcare plans (Pharmetrics; January 2000 to December 2006) for patients with bipolar disorder receiving an antipsychotic prescription were examined. Adherence was analyzed over a 12-month follow-up period after the receipt of first prescription of an antipsychotic. Adherence to antipsychotics was measured by the medication possession ratio (MPR). The MPR was calculated as the number of days that an antipsychotic medication was filled as compared with the total number of days during the follow-up period. Logistic stepwise regressions examined the association between achievement of various adherence goals and patient outcomes (hospitalization or ER visit for mental health or any reason).ResultsIn total, 7,769 patients with bipolar disorder were included. The mean MPR was 0.417, with 61.7% of individuals having an MPR < 0.50, and 78.7% an MPR < 0.75. As adherence improved, the risk of hospitalization or ER visit declined. A significant reduction in the risk of hospitalization (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.75 to 0.98) or an ER visit (OR 0.84, 95% CI 0.74 to 0.96) for any cause was associated with an MPR ≥ 0.75. An MPR ≥ 0.80 was associated with a significant reduction in the risk of a mental health-related hospitalization (OR 0.82, 95% CI 0.70 to 0.95), while an MPR ≥ 0.90 was associated with a significant reduction in risk of a mental health-related ER visit (OR 0.71, 95% CI 0.54 to 0.91).ConclusionPatients with lower antipsychotic adherence were at greater risk of hospitalizations and ER visits. Thus, any efforts to increase adherence, even in small increments, can be helpful in decreasing these risks.
Highlights
As the sixth leading cause of disability worldwide [1], bipolar disorder affects approximately 5.7 million American adults, or about 2.6% of the US population aged 18 and older, annually [2]
We examined the impact of different degrees of antipsychotic medication adherence on the risk of hospitalization or emergency room (ER) visits among individuals diagnosed with bipolar disorder
The analysis controlled for patient demographic characteristics; type of bipolar disorder; patient general health status; psychiatric prescriptions and specific comorbidities diagnosed in the preindex period
Summary
As the sixth leading cause of disability worldwide [1], bipolar disorder affects approximately 5.7 million American adults, or about 2.6% of the US population aged 18 and older, annually [2]. Two US cost-of-illness studies, one prevalence-based and the other incidence-based, have been conducted on bipolar disorder [5,6]. The prevalence-based study estimated the direct, annual costs of the disease to be $7.6 billion (in 1991 US dollars) [5], while the incidence-based study reported the lifetime, direct costs for cases of bipolar disorder diagnosed in 1998 to be $13 billion [6]. When considering the costs of medical care, a study that assessed health care claims from a database of 1.66 million people insured through more than 900 employers determined bipolar disorder to be the most expensive behavioral health diagnosis [7]. Other research has shown that inpatient care is a key driver of medical costs for patients with mental illness and, in particular, bipolar disorder [5,10]. This observational study examined the association between adherence to antipsychotics and risk of hospitalizations and emergency room (ER) visits among patients with bipolar disorder
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