(HealthDay News) – Antibiotic usage among older adults varies widely by geographical region and season, according to a study published online Sept 24 in the Archives of Internal Medicine.

Using data from the Medicare Part D database from 2007–2009, Yuting Zhang, PhD, of the University of Pittsburgh, and colleagues conducted a study to evaluate geographic variation and quarterly change in antibiotic usage in older adults in 306 hospital referral regions, 50 states and the District of Columbia, and across four regions (South, West, Midwest, and Northeast). In addition, across the four regions, quarterly change in antibiotic use was examined.

After adjustment for insurance status, patient demographics, and clinical characteristics, the researchers found considerable geographic and quarterly variation in outpatient antibiotic prescribing, which could not be accounted for by distinct prevalence of underlying conditions. Overall, the highest antibiotic usage was in the South, with antibiotic use seen for 21.4% of patients per quarter, compared with only 17.4% of patients in the West. Regardless of geographic region, antibiotic usage in older adults was highest from January to March (20.9%) and lowest from July through September (16.9%).

“Overall, areas with high rates of antibiotic use may benefit from more targeted programs to reduce unnecessary antibiotic use,” the authors write. “Although older adults may have higher risk for adverse outcomes from infection, they may also be at particularly high risk for adverse outcomes from antibiotic use. Therefore, it might be necessary to target some quality improvement initiatives toward this age group.”

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