BOSTON—Although most sore throats are caused by viral infections, primary care physicians are still prescribing antibiotics for this condition more than half the time.[1] Furthermore, they are increasingly likely to administer broad-spectrum macrolides or fluoroquinolones.

“Probably only about 10% to 20% [of adults with pharyngitis] actually needed an antibiotic because they had a strep throat,” emphasized study coauthor Jeffrey A. Linder, MD, in an interview with RESPIRATORY REVIEWS. Infection with group A ß-hemolytic streptococci is the only common cause of sore throat warranting antibiotic use, pointed out Dr. Linder, a Research and Clinical Fellow at the Harvard Medical School in Boston. Penicillin and erythromycin are the agents recommended as first-line therapy for strep throat.

It is encouraging, however, that the use of almost all antibiotic classes declined in the last year of the study, Dr. Linder said.

ANALYSIS OF PRESCRIPTION PATTERNS

Dr. Linder and his coauthor, Randall S. Stafford, MD, PhD, used data from the National Ambulatory Medical Care Survey to study antibiotic prescription patterns for sore throat among primary care physicians from 1989 to 1999. This federal survey collects information on patient visits to office-based physicians throughout the United States.

The analysis was limited to adults for whom sore throat was the primary reason for the office visit. The exclusion criteria included patient age younger than 18 years; immunosuppression resulting from diabetes, human immunodeficiency virus infection, or cancer; and a primary diagnosis of sinusitis (another cause of sore throat that might prompt antibiotic therapy).

Primary care physicians were defined as internists, family physicians, or general practitioners. Geriatricians and physicians who practice general preventive medicine were defined as internists; physicians who practice adolescent medicine were considered family physicians.

ALMOST SEVEN MILLION VISITS

During the study, adult patients made an estimated 6.7 million visits annually to primary care physicians for sore throat. The annual number of visits did not change significantly over time.

Once the exclusion criteria were applied, Drs. Linder and Stafford were left with 2,244 visits in their main sample to analyze in more detail. The patients in this sample, who had a mean age of 38 years, were predominantly white women.

During the 11-year study, 73% of the patients were given antibiotics for sore throat, and 68% of the prescriptions were for nonrecommended therapy (ie, drugs other than penicillin or erythromycin). The increase in the use of broad-spectrum macrolides and fluoroquinolones for sore throat was particularly alarming, the researchers said.

There was some good news in the study’s findings: In the last year of the study, the percentage of patients given an antibiotic prescription dropped to 57% and the percentage of those receiving an inappropriate antibiotic fell to 46%. More research is needed, Dr. Linder said, to see if this trend has continued.

PRESCRIBING PATTERNS BY SPECIALTY

Between 1989 and 1999, internal medicine physicians became progressively less likely to prescribe antibiotics for sore throat, reducing their use from 74% during the first three years of the study to 60% during the last three years. No changes were seen in the prescribing rates of family physicians or general practitioners. All three types of physicians increased their use of nonrecommended therapies during the study.

To ensure the validity of their findings, the authors repeated their analysis after excluding all primary, secondary, and tertiary diagnoses other than sore throat that could have accounted for prescription of an antibiotic. These diagnoses included acute bronchitis; acute exacerbations of chronic bronchitis; lymphadenitis; otitis media; otitis externa; pneumonia; and staphylococcal, bacterial, gonococcal, urinary tract, and skin infections.

In the repeat analysis, which included 1,852 patients, the overall rate of antibiotic use was only slightly lower (71%) than in the main analysis. However, the trend toward increased fluoroquinolone use was no longer significant.

“The decrease in the use of nearly all antibiotic classes in 1999 is a ray of hope that the message about antibiotic overuse might be getting out,” speculated Dr. Linder. However, the use of expensive broad-spectrum antibiotics that can induce resistance is still quite high, he and Dr. Stafford pointed out. Efforts to encourage appropriate antibiotic use by patients and physicians should continue, they stressed.

—Timothy Begany