Prior medication adherence of participants and non participants of a randomized controlled trial to improve patient adherence in cardiovascular risk management

• Published in: BMC medical research methodology Vol. 19; no. 1; pp. 95 - 9
• Main Authors: Sieben, A, Bredie, S J H, Luijten, J C H B M, van Laarhoven, C J H M, van Dulmen, S, van Onzenoort, H A W
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 09.05.2019; BioMed Central; BMC
• Subjects: Acute coronary syndromes; Adherence; Blood pressure; Cardiac patients; Cardiovascular disease; Cardiovascular diseases; Cardiovascular Diseases - mortality; Cardiovascular Diseases - prevention & control; Clinical trials; Drugs; Ethics; Evidence-based medicine; Female; Health Knowledge, Attitudes, Practice; Heart attacks; Humans; Hypertension; Informed Consent; Intervention; Lipids; Male; Medical research; Medication Adherence - psychology; Medication Adherence - statistics & numerical data; Middle Aged; MMS (Multimedia messaging service); Morbidity; Mortality; Participation; Patient compliance; Patients; Prevention; Questionnaires; Randomized controlled trials; Retrospective Studies; Risk Factors; Risk management; Risk Reduction Behavior; Secondary Prevention - methods; Selection bias; Surveys and Questionnaires; Netherlands; Adherence; Participation; Informed consent; Selection bias; Randomized controlled trials
• ISSN: 1471-2288; 1471-2288
• DOI: 10.1186/s12874-019-0743-7

Poor medication adherence is a major factor in the secondary prevention of cardiovascular diseases (CVD) and contributes to increased morbidity, mortality, and costs. Interventions for improving medication adherence may have limited effects as a consequence of self selection of already highly adherent participants into clinical trials. In this retrospective cohort study, existing levels of medication adherence were examined in self-decided participants and non-participants prior to inclusion in a randomized controlled study (RCT), evaluating the effect of an intervention to improve adherence. In addition, the non-participants were further divided into 'responders' and 'non responders'. All individuals had manifest cardiovascular disease and completed a questionnaire with baseline characteristics, the Beliefs about Medicines Questionnaire (BMQ) and the Modified Morisky Scale® (MMS®) as part of a regular screening program. A logistic regression was conducted to examine the relationship between study participation willingness, adherence level and the beliefs about medication. According to the MMS® the adherence level was comparable in all groups. In both (non)-participants groups, 36% was classified as high adherent; 46% participants versus 44% non-participants were classified as medium adherent and 19% of the participants versus 20% of the non-participants were low adherent (p = 0.91. The necessity concern differential (NCD) from the BMQ was 3.8 for participants and 3.4 for non-participants (p = 0.32). This study shows that adherence to medication and beliefs about medication do not differ between participants and non-participants before consenting to participate in an RCT. The study design seems not to have led to greater adherence in the study group.