Considerable geographic and seasonal variation exists in antibiotic use among older Americans, suggesting possible targets for redoubled efforts at combating overprescribing, a national study determined.
For instance, the rate of antibiotic use among patients enrolled in Medicare Part D was 21.4% per quarter in the South compared with 17.4% in the West (P<0.01), according to Yuting Zhang, PhD, of the University of Pittsburgh, and colleagues.
The peak of usage was during the first 3 months of the year, falling to its lowest in the third quarter months of July through September (16.9% versus 20.9%, P<0.01), the researchers reported online in Archives of Internal Medicine.
"Overall, areas with high rates of antibiotic use may benefit from more targeted programs to reduce unnecessary antibiotic use," they observed.
Despite 15 years of effort on the part of public health authorities, excessive use of antibiotics persists, resulting in adverse reactions on the individual level and rampant resistance on the population level.
Older individuals may be at higher risk for antibiotic-related complications because of their greater burden of comorbidities, but little is known about prescribing patterns among this group.
Therefore, Zhang and colleagues examined Medicare Part D data for the years 2007 through 2009, analyzing data at three levels: according to more than 300 hospital referral regions, in all 50 states, and in four main geographic areas (Northeast, Midwest, South, and West).
Specifically, they looked at prescribing for bacterial pneumonia, which generally is considered an appropriate use of antibiotics; acute nasopharyngitis, which usually is viral and is not an indication for antibiotics; and other respiratory tract infections such as sinusitis and bronchitis, which in some cases warrant treatment.
For their analysis, they adjusted for patient demographics, clinical characteristics, and insurance status.
The South not only had the highest rates of use of antibiotics overall, but also had higher rates for every class of antibiotic (P<0.05), while use of penicillins, macrolides, and quinolones were used least in the West.
All the individual classes were used most often in the first quarter of the year, and least during the third quarter.
The researchers also considered whether the variations in prescribing could be explained by differing prevalence of the three conditions in question, and found the opposite: The Northeast had the highest rate of bacterial pneumonia, but also the lowest rate of antibiotic use for the condition (P<0.05).
Finally, they looked at variations in spending on antibiotics, and again found significant variation, with a ratio of 1.31 across states comparing the 75th percentile with the 25th.
When the comparison was across regions, the ratio of the 75th to 25th percentile in spending was 1.32, which was even higher than in some previous studies, according to the researchers.
Greatest expenditures were seen in Mississippi and Alabama, while the lowest costs were found in Maine, New Hampshire, Oregon, and Wyoming.
In discussing their findings, the researchers emphasized the importance of clarifying the use of antibiotics among the elderly, in that older patients may be more at risk for poor outcomes when infections are untreated.
"On the other hand, older patients might be subject to more severe adverse outcomes of antibiotic use regardless of whether the antibiotic actually was indicated, including (for example) Clostridium difficile colitis, cognitive disturbance with quinolone use, and clinically significant drug-drug interactions," they noted.
Limitations of the study included the researchers' inability to control for factors such as disease severity and the possibility of miscoding.
Nonetheless, they argued that their findings have important implications, and particularly that quality improvement programs may be needed for the treatment of older adults with respiratory infections.
That significant challenges remain was echoed in an invited commentary by Ralph Gonzales, MD, and colleagues from the University of California San Francisco.
"We need to find better ways to compel individuals and organizations to address the significance of the problem of antibiotic overuse and to increase the readiness for change and quality improvement of ambulatory practices in the United States," wrote Gonzales and colleagues.
Furthermore, they added, "strategies to achieve transformation at these levels may need to differ substantially from the current educational approaches that have been in use among patients and clinicians thus far."
The study was funded by the Centers for Medicare & Medicaid Services, the Institute of Medicine, the National Institute of Mental Health, the Agency for Healthcare Research and Quality, the National Institute on Aging, and the American Federation for Aging Research.
All authors of the paper and invited commentary reported no financial conflicts.
- Reviewed by Dori F. Zaleznik, MD Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Archives of Internal MedicineSource Reference: Zhang Y, et al "Geographic variation in outpatient antibiotic prescribing among older adults" Arch Intern Med 2012; DOI: 10.1001/archinternmed.2012.3717.
Archives of Internal MedicineSource Reference: Gonzales R, et al "Can implementation science help to overcome challenges in translating judicious antibiotic use into practice?" Arch Intern Med 2012; DOI: 10.1001//2013/jamainternmed.532.