A study of refill non-compliance and predictors of refill non-compliance to tricyclic and SSRI antidepressants in a population setting

Powell, Tammy Lynette (1997) A study of refill non-compliance and predictors of refill non-compliance to tricyclic and SSRI antidepressants in a population setting. Masters thesis, Memorial University of Newfoundland.

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Abstract

The current study utilized the Atlantic Blue Cross Prescription Drug Database to examine patient: refill compliance to antidepressants from the tricyclic and selective-serotonin re-uptake inhibitors (SSRII classes. The primary goals of the study were to describe and compare compliance between the tricyclic and SSRI users, to ascertain whether patient age and gender, treatment cost, and regimen complexity were predictors of non-compliance, and to evaluate the problems involved with utilizing the Atlantic Blue Cross Database for compliance research. -- Non-compliance was measured by using three outcome measures. First the percentage of non-compliant days (defined as the percentage of days during treatment without medication) was found. Second, the early medication 'stoppers' were compared to the medication 'continuers'. Finally, the time course of non-compliance was studied by finding the time till the first non-compliant gap for users. -- Results showed that the mean percentage of noncompliant days was 8.4% (95% CI; 7.9-8.9) for the tricyclic and SSRI users who filled more than one prescription. In addition, between 8.1-11.4% of users stopped the antidepressant medication early. Survival analysis suggested that the greatest drop in the cumulative probability of having a non-compliant gap occurred early in treatment for both classes. No differences were found in the comparisons of the tricyclics and the SSRI's in terms of non-compliance. The predictor variable age was weakly associated with noncompliance; as age increased, non-compliance decreased. In addition, regimen complexity as measured by the number of concurrent medications and the number at doses per day was also weakly associated with non-compliance. More specifically, as the number of concurrent medications increased, compliance increased and as the number of doses per day increased, compliance decreased. -- A number of problems were identified with the Blue Cross Database. In a number of cases, data was missing. Data contamination problems were identified that were probably the result of data entry errors. Cleaning protocols were developed to deal with some of these problems. A number of other problems were also identified which were inherent to the database. For example, there was a lack of documentation concerning dates of entry and exit to the Blue Cross Program.

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