Pharmaceutical companies information and antibiotic prescription patterns: A follow-up study in Spanish primary care

OBJECTIVES: To assess the impact of sources of drug information on antibiotic prescribing patterns (quantity and quality) among primary care physicians. METHODS: We conducted a cohort study on primary care physicians who were actively engaged in medical practice in 2010 in a region in north-west Spain (Galicia), fulfilling inclusion criteria (n = 2100). As the independent variable, we took the perceived utility of 6 sources of information on antibiotics, as measured by the validated KAAR-11 questionnaire. As dependent variables, we used: (1) a quality indicator (appropriate quality, defined as any case where 6 of the 12 indicators proposed by the European Surveillance of Antimicrobial Consumption Network [ESAC-Net] were better than the mean values for Spain); and, (2) a quantity indicator (high prescribing), defined as any case where defined daily doses (DDD) per 1 000 inhabitants per day of antibacterials for systemic use were higher than the mean values for Spain. The adjusted odds ratio for a change in the interquartile range (IqOR) for each sources of information on antibiotics was calculated using Generalized Linear Mixed Models. RESULTS: The questionnaire response rate was 68%. Greater perceived utility of pharmaceutical sales representatives increases the risk of having high prescribing (1/IqOR = 2.50 [95%CI: 1.63–3.66]) and reduces the probability of having appropriate quality (1/IqOR = 2.28 [95%CI: 1.77–3.01]). Greater perceived utility of clinical guidelines increases the probability of having appropriate quality (1/IqOR = 1.25 [95%CI: 1.02–1.54]) and reduces the probability of high prescribing (1/IqOR = 1.25 [95%CI: 1.02–1.54]). CONCLUSIONS: Sources of information on antibiotics are an important determinant of the quantity and quality of antibiotic prescribing in primary care. Commercial sources of information influence prescribing negatively, and clinical guidelines are associated with better indicators.