Measuring Patients' Knowledge About Adverse Effects of Angiotensin-Converting Enzyme Inhibitors.

BACKGROUND: Knowledge about adverse effects of medications is an important part of proper medication use and prerequisite for good treatment adherence.

OBJECTIVE: The aim of our study was to construct, develop, and test a new questionnaire for the measurement of patients' knowledge about adverse drug reactions of angiotensin-converting enzyme (ACE) inhibitors.

METHODS: The 8-item questionnaire was constructed to measure adverse reactions to ACE inhibitors. The questions were closed, with 7 offered answers, in the form of a Likert scale. It was tested for psychometric properties on patients who visited their general practitioners at state-owned health facilities in 5 Serbian cities: Belgrade, Kragujevac, Banja Luka, Gracanica, and Despotovac.

RESULTS: The questionnaire was tested on 259 patients from general practice, taking an ACE inhibitor for more than 3 months. Experience with at least 1 adverse effect of ACE inhibitor was reported in 64 patients (24.7%), only 94 patients (36.3%) previously received any form of information about at least 1 adverse effect of ACE inhibitors from health workers, and only 42% expressed knowledge of any adverse events. The patients who were informed knew about the following adverse events as phrased in the official patient information leaflets: severe dizziness or light-headedness (44%); cough (37%); swelling of the hands, face, lips, or tongue (32%); indigestion (22%); headache (51%); and difficulty in breathing (15%). The questionnaire showed satisfactory internal consistency, with Cronbach α of 0.767, and individual scores correlated with general education of the patients. Factorial analysis revealed 2 domains (subscales): the first one with 5 questions is directed to adverse effects the patients may physically experience directly, whereas the second with 3 questions measures knowledge about adverse effects that could be experienced only indirectly, through conditions caused by the adverse effects.

CONCLUSIONS: The questionnaire about knowledge of ACE inhibitors' adverse effects is a reliable and probably valid instrument for measuring patients' knowledge about adverse effects of ACE inhibitors.