Decreasing trends, and geographical variation in outpatient antibiotic use: a population-based study in Central...

Antimicrobial overuse and misuse of broad-spectrum antibiotics increases the risk for antimicrobial resistance. Investigating unwarranted variation in antibiotic prescription has therefore gained global priority.

We examined recent time trends in the utilization of narrow- and broad-spectrum antibiotics as well as the variation in antibiotic use by sex, age, and municipality of residence. Complete individual-level data on all redeemed out-of hospital prescriptions for antibiotics in the entire adult population of Central Denmark (1.3 million inhabitants) was obtained for the period 2006-2015.

Following an initial increase of 2% between 2006 and 2011, the overall rate of redeemed prescriptions for antibiotics per 1000 person years declined by 17% between 2011 and 2015. Among persons aged over 65 years, the decline in use began later (from 2013) and was less pronounced. Antibiotic use in 2015 remained substantially higher among females (289/1000 person-years) vs. males (182/1000 person-years) and among the very old (520/1000 person-years in >85y old) vs. middle-aged (204/1000 person-years in 45-65y old). A decreasing trend in antibiotic use over time was observed in all municipalities, mainly due to a decrease in narrow-spectrum antibiotics. However, a striking and unexplained 1.6-fold geographical variation in antibiotic use, including tetracyclines, macrolides and fluoroquinolones remained in 2015. Of concern, among females aged ≥65 years and males aged ≥85 years, a continuous increasing trend in broad-spectrum antibiotic use was observed.

Antibiotic use has decreased almost 20% in Central Denmark after 2011, possibly related to a nationwide antibiotic stewardship program in Denmark. However, substantial geographical variation in antibiotic prescription remains and the use of broad-spectrum antibiotics has increased in adults of older age. Continuous focus on avoiding unnecessary use of broad-spectrum antibiotics is requested.