About two-thirds of patients with type II diabetes do not take their oral hypoglycaemic treatment properly. Lack of adherence increases "significantly" when patients have to take more than one drug, say Dr Peter Donnan and colleagues (University of Dundee).
The findings arose from a study presented at the spring meeting of the British Diabetic Association in Brighton on March 15. The study involved 2,920 subjects with type II diabetes who had received a prescription for an oral hypoglycaemic drug for over 12 months. Of these, 1,329 were prescribed a sulphonylurea alone, 531 received metformin alone and 1,060 were taking both metformin and a sulphonylurea.
Adherence (measured in terms of the number of prescriptions dispensed as a percentage of those issued) was considered to be adequate if it was greater than 90 per cent. This was similar for monotherapy, with 31 per cent of the sulphonylurea-only group and 34 per cent of those taking metformin only adhering to therapy. However, the patients that were taking both drugs only achieved 13 per cent adherence. The median number of days of drug coverage per year for the mono- and multitherapy groups was about 300 and 266, respectively. There was an observed decrease in adherence of 22 per cent for each increase in frequency of daily dose, the authors reported. They concluded that the data illustrate that adherence was "uniformly very poor". The research was carried out, using anonymised data, by the DARTS/MEMO collaboration (Diabetes Audit and Research in Tayside, Scotland/Medicines Monitoring Unit) and the statistical analysis was funded by Aventis Pharma Ltd.
Commenting on the findings, Dr David McNaughton (research pharmacist, University of Dundee) told The Journal on March 14 that the study presented an opportunity for community and primary care pharmacists, in particular, as they saw patients more often than other members of the health care team. Pharmacists could improve concordance in patients with diabetes in two ways, he said. First, they could increase the likelihood of adherence by reviewing all drugs being taken, in order to reduce polypharmacy. Secondly, by helping patients to understand the long-term importance of taking their drugs regularly, pharmacists would increase the likelihood that tablets would be taken. Dr McNaughton said that both advice to patients and drug treatment must be tailored to the individual.