The effectiveness of medicines : the relationship between patient and prescriber expectations of effectiveness of medicines and compliance

Abstract

Effectiveness of medicines as reported in the literature can be difficult to interpret and explain to patients in clinical practice. A patient-orientated measure of effectiveness, the Category of Effectiveness (COE) was developed in 1988 by Dr Holford, Department of Pharmacology and Clinical Pharmacology, University of Auckland, School of Medicine. This was designed to examine the effectiveness of medicines in terms of easily understood patient-orientated outcomes which may influence the patient's daily living or quality of life. As part of their pharmacology training, third-year medical students were assigned two medicines to evaluate in terms of COE and asked to calculate a rate/1000 treatments or rate/1000 treatment years i.e. a Rate of Effectiveness (ROE). Interviews with three health professionals to obtain their opinions of the assigned medicines in terms of COE and ROE were recorded. An ordered scale of effectiveness, the Likelihood of Effectiveness (LOE), was developed by Dr Holford and the author in order to review these student projects. A review by the author of 201 of these projects over a five year period, suggests that health professionals expectations of some commonly prescribed medicines are over-optimistic. A literature search to obtain effectiveness information in terms of COE and LOE of twelve commonly prescribed medicines, Augmentin, cefaclor, beclomethasone, salbutamol, atenolol, captopril, enalapril, ranitidine, paracetamol, diclofenac, aspirin, and triazolam was undertaken. Such information was found to be limited in the literature as clinical trial results are seldom expressed in such terms. Opinions of patients and prescribers about The Category of Effectiveness (COE) and Likelihood of Effectiveness (LOE) of commonly prescribed medicines have not been examined in clinical practice. The influence these may have on medicine use was therefore surveyed for the twelve medicines listed above. One hundred and fifty-three patients received 247 prescriptions for one or more of these medicines. Expectations of patient and corresponding prescriber were similar in terms of COE, but LOEs differed significantly for 8 of the 12 medicines. Neither COE nor LOE were significantly related to patient compliance which was measured after 5-10 days. Most compliance-failure was seen in patients whose medicine was newly prescribed for short-term treatment. Information other than basic instructions was received by <25% of patients from either the prescriber or the pharmacist. At the surgery/hospital only 19% of patients remembered receiving written information about their medicine, which increased to 22% at the home visit. Of the patients who completed the medicines information questionnaire, only 59/152 (38.6%) would like more general information about their medicines. Despite this, 139/152 (91.4%) patients would like more specific information on how their medicine works, and 130/152 (85.5%) want to know how well it can be expected to work. This information has not been given to patients in the past. It was hypothesised that providing effectiveness information to patients may have some effect on compliance. The influence on compliance that providing written medicine effectiveness information as pamphlets from community pharmacists may have, was examined for 211 patients in a double-blind controlled trial. Patients who presented a prescription for beclomethasone for asthma or enalapril for hypertension were invited to participate. Each patient received one of three pamphlets, 1. specific medicine information pamphlet, 2. specific medicine information plus effectiveness information, 3. a control pamphlet containing general medicine information. Medicine knowledge was significantly increased by both the medicine information pamphlet (p=0.028) and the medicine and effectiveness information pamphlet (p=0.016) compared to control. Significantly more beclomethasone than enalapril patients showed compliance-failure (p=0.001) although this was independent of the pamphlet given. Expectations of LOE were related to patient compliance for beclomethasone patients, but not for enalapril patients. Significantly more beclomethasone patients with higher expectations of LOE were compliant (p=0.017). Satisfaction with the information contained in the pamphlet had a positive effect on patient compliance with beclomethasone individually. Patient-orientated measures of effectiveness such as COE (Category of effectiveness) and LOE (Likelihood of effectiveness) can identify patient expectations, increase patient knowledge and may provide some insight into patient compliance failure.