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

David F Blackburn,1 Shenzhen Yao,2 Jeff G Taylor,1 Qais Alefan,3 Lisa M Lix,4 Dean T Eurich,5 Niteesh K Choudhry6 1College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; 2Public Health Surveillance Unit, Vancouver Coastal Health Authority, Vancouver Coastal Health, Vancouver, British Columbia, Canada; 3Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, Jordan; 4Department of Community Health Sciences, Max Rady Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada; 5School of Public Health, University of Alberta, Edmonton, Alberta, Canada; 6Department of Medicine, Brigham and Women’s Hospital/Harvard Medical School, Boston, MA, USACorrespondence: David F Blackburn, Email [email protected]: 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

Keywords

• adherence
• persistence
• beliefs
• attitudes
• expectations