Roughly 40 percent of patients with schizophrenia are regularly noncompliant in taking their medication, and noncompliance is associated with significantly higher medical costs for both outpatient and hospital care, according to an article in the April issue of the American Journal of Psychiatry.

The current study was conducted in a large, ethnically and socioeconomically diverse US area and involved 1,619 adult patients receiving care through a single system. Analyses were based on prescriptions filled for oral antipsychotic medications. The researchers considered a person partially adherent or non-adherent when a prescription was not refilled on schedule. Insurance claims were used to determine hospitalization in a given year and the total amount paid by the government insurance agency for inpatient care.

Of the 41 percent of patients considered noncompliant, 24 percent were non-adherent and 17 percent were partially adherent to the prescribed drug schedule. Interestingly, researchers found that 19 percent refilled prescriptions more frequently than required for their drug schedule (the excessive filler group).

Psychiatric hospitalization was strongly related to the degree of drug adherence, with non-adherent patients 2.5-fold more likely to be hospitalized than adherent patients. Partially adherent and excess filler patients were 80 percent more likely to be hospitalized. Similar increases were found in hospitalization for medical (non-psychiatric) conditions.

The likelihood of adhering to an antipsychotic medication generally increased with age. For example, adherence in those younger than 30 years was approximately 36 percent compared with 48 percent in people 60 years old or more. Non-adherence had a high association with living situation. About 50 percent of patients in the study lived independently, with 25 percent in assisted living facilities, 19 percent living with family members, and 5 percent homeless. The highest compliance was among those living with family members or in an assisted living facility. Less adherent were individuals living independently, or those designated as homeless.

“Our findings argue for new approaches to improve the effectiveness of health services delivered to the mentally ill through the existing network of agencies and providers. They also suggest targeting subgroups for specific improvement strategies to protect high-risk patients with schizophrenia,” the investigators wrote.

The study’s senior author, Dilip Jeste, MD, also noted that a little more than half of the people who filled prescriptions more frequently than needed per schedule were individuals who used multiple antipsychotic medications.