Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Epidemiology and Biostatistics

Supervisor

Lizotte, Daniel J.

2nd Supervisor

Anderson,Kelly K.

Co-Supervisor

Abstract

Over the past two decades, the use of antipsychotics has increased tremendously worldwide, and second-generation antipsychotics (SGAs) have been the main driver of this trend. The extensive use of SGAs for off-label purposes has raised concerns over their role in clinical practice. In particular, studies have revealed serious metabolic and cardiovascular effects, and evidence is lacking on SGAs’ effectiveness. Despite the concerns, the extent and pattern of SGAs’ off-label use is largely unknown within the context of the Canadian primary health care system. Using electronic medical record (EMR) data from 14 practices in southwestern Ontario, we investigated the number of patients who were prescribed SGAs in primary care for off-label uses between 2005 and 2015. Furthermore, we compared the history of diagnosis of the off-label population to this history of a reference population (non-SGA users) in the same setting.

The majority of patients who were prescribed SGAs lacked records of approved indications (72%), and the medications appeared to be prescribed much more frequently for off- than on-label uses in any given year in the study period. SGAs are reported to be prescribed off-label for a variety of conditions; in our data, SGA users in the off-label group were more likely to have a history of dementia, anxiety and depressive disorders, personality disorders, and substance abuse, which may have been the off-label indications for which the patients were prescribed SGAs in primary care.

Our findings indicate a need to promote evidence-based prescription of SGAs as well as the provision of further evidence on their use in off-label indications. Although off-label use has often preceded and outstripped supporting evidence, we encourage the regulatory agency, pharmaceutical industry, and science community to implement innovative policies and solutions to address the off-label prescribing practice

Summary for Lay Audience

Second-generation antipsychotics (SGAs) are a group of medications that initially were tested for certain mental diseases (schizophrenia, bipolar disorders, etc.) and were officially assessed and received approval for market entry. Later, studies reported that these medications were used for conditions for which there is no standard treatment or for patients who did not respond well to standard medications. Such uses are called off-label as they are not officially assessed and approved in contrast to on-label uses (uses for approved conditions). Off-label use of existing medications may be a helpful option for certain patients but there are concerns that without enough experiments, there would not be enough information on how effective and safe these agents might be in off-label uses.

We studied patients who were prescribed SGAs in primary care between 2005 and 2015 in southwestern Ontario and compared the history of their diagnosis with the non-SGA users. The majority of patients in our data (72%) lacked records of approved indications and seemed to be off-label users. Health conditions like dementia, anxiety and depressive disorders, personality disorders, and substance abuse seemed to be the off-label uses of SGAs in our data.

Our findings show a need for further research in this area as well as further safe and effective medications for a variety of less-known psychiatric conditions.

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