Antibiotic Adherence in Respiratory Infections Disappointingly Low

Far more patients claimed to have adhered to their antibiotic prescriptions than actually did, according to the results of a study that used an electronic system to record when pill bottles were opened.

Less than a third of patients who were prescribed antibiotics for respiratory infections demonstrated excellent adherence, and 4 in 10 of those who fell short of excellent adherence mistakenly reported that they never missed a dose, according to the results of a study published online on October 31, 2012, in the International Journal of Infectious Diseases.

The researchers performed a prospective study between 2003 and 2008 of patients with suspected bacterial pharyngitis and lower respiratory tract infections at 5 primary care clinics in Catalonia, Spain. Adherence to medication was measured using an electronic system that recorded every time a patient's pill bottle was opened. In addition, patients were asked whether they had missed any doses at the end of their scheduled course of antibiotics.

The study included analysis on 428 patients. Of these patients, 251 (58.6%) were diagnosed with lower respiratory tract infections, and 177 (41.4%) were diagnosed with bacterial pharyngitis. As treatment, 236 (55.1%) were prescribed antibiotics 3 times per day, 151 (35.3%) were prescribed antibiotics twice per day, and 41 (9.6%) were prescribed antibiotics once per day. The mean age of the patients was 47.1 years, and 231 (54.0%) were women.

The electronic monitoring system found that 265 (61.9%) of the patients opened their pill containers at least 80% of the number of times they were supposed to open it based on their prescription; 146 (34.1%) of the patients opened their pill container at least as many times as they were supposed to on at least 80% of the days in their medication course; and 165 (38.6%) of the patients opened their pill container close to the recommended dosing time for at least 80% of prescribed doses. In all, just 130 (30.4%) of the patients demonstrated excellent adherence by achieving at least 80% in each of these 3 adherence measures, and an additional 53 (12.4%) of the patients came close to achieving excellent adherence.

When asked whether they had ever missed a dose during their antibiotic therapy, however, 254 (59.3%) of the patients reported that they had missed no doses, suggesting a much higher adherence rate than was observed through electronic monitoring. Indeed, of the 298 patients who did not demonstrate excellent adherence, 124 (41.6%) reported never forgetting to take an antibiotic dose.

Based on electronic monitoring, medication adherence rates were significantly associated with the number of daily doses of antibiotics. Among those taking antibiotics once per day, 89.2% demonstrated excellent adherence, compared with 51.0% of those taking antibiotics twice per day and just 8.1% of those taking antibiotics 3 times per day.