Objectives: To compare the population consenting for a study of the effectiveness of a pharmacist-run medication review clinic with the population not consenting for patients aged over 65 years old with respect to age, sex and number of repeat medicines. To explore the reasons why some patients declined to consent to the study.
Methods: Letters were sent to 2,403 patients aged 65 and over and taking at least one repeat medicine from 4 general practices. If no reply was received to a second letter they were followed up by telephone. If they declined to consent they were asked for their reasons. Data for consenting and non-consenting patients was collected on the stratification factors: age, sex and number of repeat medicines. Multiple logistic regression was used to assess the association of each factor with consent rates.
Results: Consenting patients were dissimilar to non-consenting patients. Patients were less likely to consent if they were older, OR (95% CI) = 0.54 (0.46, 0.64), or female, OR (95% CI) = 0.74 (0.63, 0.88). Patients were more likely to consent if on 5 or more repeat medicines: OR (95% CI) = 1.3 (1.1, 1.5). Ten broad categories of reasons why patients did not wish to participate were identified from the patient interviews.
Conclusions: Patients were less likely to give their consent if they were elderly, female and on fewer repeat medicines. A number of administrative and behavioural factors were identified which reduced the chances of informed consent being given. These factors need to be addressed to maximise numbers of consenting patients in medication review studies.