Quality Parameters of the Self-Report Scale of Patients' Beliefs about Drug Therapy

Abstract

Background and Aim: Pharmacists in community pharmacies are experts in drug therapy, being in direct and regular contact with patients. Their beliefs about drugs, the need for medication therapy and medication adherence can be influenced by pharmacists' advice. Thus, we aim to develop and validate a questionnaire about drug therapy to be applied to patients. Materials and Methods: The questionnaire was based on the “Beliefs about Medicines Questionnaire” and the “Medication Adherence Report Scale” of Horne et al. The response scale was a five-category Likert type. The quality parameters of the self-report scale were highlighted through sequential exploratory study of the mixed method. A cross-sectional study was conducted on 809 patients from Romania, aged between 18 and 87 years (mean age 35.81±13.52), 190 men and 619 women, between January and June 2023. The questionnaire with 14 items was completed on google form [https://docs.google.com/forms/d/e/1FAIpQLSdzU2tQQKphyqbHNbDWOTzWL-Hf5XBbUA6FeU9rZFf0MLlPLQ/viewform]. Statistical analysis was done in SPSS 27.0. Results: Good values show Inter-rater Agreement (72%), Item Content Validity for clarity (92%) and relevance (88%). Very good values indicate Scale Content Validity for clarity (96.2%), relevance (93.9%) and completeness (100%). Cronbach's alpha shows an acceptable internal consistency of the items (α=0.795). The factorial analysis highlights three factors (with Eigen values > 1.0), corresponding to the domains of the questionnaire. The mean score of beliefs about medicines is 3.49±0.57; the mean score of beliefs about drug treatment is 2.85±0.95; the average score of medication adherence is 2.67±0.73; significant statistical differences were found depending on the characteristics of the patients (p≤0.05). Conclusions: The self-report scale of patients' beliefs about drug therapy met the quality parameters for our results in order to be sustainable. Patients were partially convinced of the importance of drug therapy, they were not convinced of the need for treatment, but they were adherent to the prescribed drugs.