Measuring the Influence of Side Effect Expectations, Beliefs, and Incident Side Effects on the Risk for Drug Discontinuation Among Individuals Starting New Medications, a Cross-sectional Study

Abstract

Purpose

To measure the impact of beliefs, expectations, side effects, and their combined effects on the risk for medication nonpersistence.

Patients and methods

Using a cross-sectional design, individuals from Saskatchewan, Canada who started a new antihypertensive, cholesterol-lowering, or antihyperglycemic medication were surveyed about risk factors for nonpersistence including: (a) beliefs measured by a composite score of three questions asking about the threat of the condition, importance of the drug, and harm of the drug; (b) incident side effects attributed to treatment; and (c) expectations for side effects before starting treatment. Descriptive statistics and logistic regression models were used to quantify the influence of these risk factors on the outcome of nonpersistence. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated.

Results

Among 3,029 respondents, 5.8% (n=177) reported nonpersistence within four months after starting the new drug. After adjustment for numerous covariates representing sociodemographics, health-care providers, medication experiences and beliefs, both negative beliefs (OR: 7.26, 95%CI: 4.98–10.59) and incident side effects (OR: 8.00, 95%CI: 5.49–11.68) were associated with the highest odds of nonpersistence with no evidence of interaction. In contrast, expectations for side effects before starting treatment exhibited an important interaction with incident side effects following treatment initiation. Among respondents with incident side effects (n=741, 24.5%), the risk for early nonpersistence was 11.5% if they indicated an expectation for side effects before starting the medication compared to 23.6% if they did not (adjusted OR: 0.38, 95%CI: 0.25–0.60).

Conclusion

Expectations for side effects may be a previously unrecognized but important marker of the probability to persist with treatment. A high percentage of new medication users appeared unprepared for the possibility of side effects from their new medication making them less resilient if side effects occur.

Keywords:

• adherence
• persistence
• beliefs
• attitudes
• expectations

Acknowledgment

This paper has been uploaded to medRxiv as a preprint: https://www.medrxiv.org/content/10.1101/2023.09.18.23295758v1.

Disclosure

Dr Niteesh Choudhry reports grants from National Institutes of Health, personal fees from RxAnte, outside the submitted work. The authors report no other conflicts of interest in this work.

Additional information

Funding

This study was funded from a peer reviewed research grant from the Canadian Institutes of Health Research (CIHR grant number 130343). CIHR had no role in the study design, collection, analysis, interpretation of data, writing of the report, or in the decision to submit the article for publication. In addition, all authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. This study is based in part on de-identified data provided by the Saskatchewan Ministry of Health. The interpretation and conclusions contained herein do not necessarily represent those of the Government of Saskatchewan or the Saskatchewan Ministry of Health.