Background: Drug benefit providers can decrease prescribing of specific medications through prior authorization policies. In Saskatchewan, certain second generation antipsychotics (SGAs) are recognized as first-line agents to manage schizophrenia; but, require prior authorization because their coverage is restricted in other conditions. We aimed to determine if the need for prior-authorization substantially diminishes prescribing of first-line SGAs in comparison to unrestricted agents.
Objectives: To conduct an ecological comparison of SGA prescribing with changes in prior- authorization policies between 1997 and 2005 using health-administrative databases in Saskatchewan, Canada.
Method: Eligible subjects were discharged from hospital with a first-time primary diagnosis of schizophrenia between 1997 and 2005. SGAs dispensed within 7 days of discharge were used to estimate prescribing preferences for olanzapine and quetiapine relative to risperidone. Percentages of SGA use were age and sex standardized to the 2000 cohort.
Results: Out of 1,277 eligible patients, 521 (41%) received 564 SGA dispensations within 7-days of hospital discharge. Between 1997 and 1998, risperidone was the only SGA covered for first-line use and made up 72.6% (82/113) of SGA use while olanzapine made up 27.4% (31/113) for a crude preference ratio of 0.38 (27.4/72.6). Risperidone use decreased to 65.8% in 1999-2002 and to 47.4% in 2003-2005 as a percentage of SGA dispensations. Correspondingly, the preference ratios for olanzapine and quetiapine increased from 0.40 to 0.57 and from 0.12 to 0.54 in these respective periods.
Conclusions: The requirement for prior-authorization does not appear to substantially diminish prescribing of first-line SGAs for the treatment of schizophrenia in Saskatchewan, Canada.