CDC study: Antibiotics still widely overused for respiratory infections

The overuse of antibiotics to treat acute respiratory infections (ARIs), including influenza, is still widespread, according to a new study that covered close to 15,000 patients in five regions around the country over two flu seasons.

Researchers with the Centers for Disease Control and Prevention (CDC) found that 41% of antibiotic prescriptions written for patients with ARIs were inappropriate, according to their report published today in JAMA Network Open.

Among other things, the team found that close to 30% of patients who had lab-confirmed flu were prescribed antibiotics, though flu is a viral infection, and that more than a few sore-throat patients received such prescriptions even though they tested negative for a bacterial cause.

Flu vaccine network sites used

The researchers used data collected by the five regional sites in the US Influenza Vaccine Effectiveness Network during the 2013-14 and 2014-15 flu seasons. The study included 57 clinics in the first season and 66 in the second.

The clinics enrolled consenting patients at least 6 months old who had an ARI and a new cough. For research purposes only, all patients were tested for flu. The team checked the patients' recent medical histories and gathered data on antibiotic and flu antiviral prescriptions written within 7 days after enrollment.

A total of 14,987 ARI patients were included, with a mean age of 32; 58% of them were female and 80% were white. Providers prescribed antibiotics for 6,136 (41%) of the patients. Fifty-six percent of the prescriptions were for broad-spectrum antibiotics, with azithromycin accounting for 37% of all prescriptions.

Of the 6,136 patients who were prescribed the drugs, 41% (2,522) had diagnoses for which antibiotics are not indicated, the report says. An overwhelming majority of this group (2,106, 84%) were diagnosed as having a viral upper respiratory tract infection or bronchitis.

There were 3,306 patients (22% of the total) who had lab-confirmed flu and were not found to have pneumonia. Of these, 945 (29%) were prescribed an antibiotic, which accounted for 17% of all antibiotic prescriptions for patients with non-pneumonia ARI.

The authors comment that widely available point-of-care flu tests—which were infrequently used in the study—vary in reliability and are not recommended for use in ruling out flu when making treatment decisions. They suggest that the development of better point-of-care flu tests may improve treatment decisions for ARI patients during flu season and thus reduce unnecessary antibiotic use.

Antibiotics used despite negative strep tests

The study also revealed that 168 patients with pharyngitis received antibiotic treatment even though they had tested negative for Group A Streptococcus (GAS). They made up 38% of the 440 pharyngitis patients who were given antibiotics. The authors commented that national guidelines on pharyngitis recommend antibiotic treatment for lab-confirmed GAS only.

In other findings, it appeared that many of the 1,200 patients who were prescribed an antibiotic for sinusitis were treated inappropriately, the authors said. Of that group, 454 patients (38%) had symptoms for 3 days or less before the outpatient visit, which suggests acute viral sinusitis.

The researchers also found that older adults were more likely than younger adults and children to receive antibiotics without an appropriate indication and were far more likely to receive broad-spectrum antibiotics, especially azithromycin, which was prescribed for nearly a quarter of adults over age 50, regardless of diagnosis.

The findings are consistent with previous studies based on national survey data that indicate clinicians too often prescribe antibiotics for ARIs, the authors said. However, "the proportion of patients prescribed antibiotics for conditions such as pharyngitis and bronchitis was lower in this study compared with other studies, and assessment of antibiotic overuse may be underestimated."

The researchers acknowledge several other imitations of the study. For example, medical histories for some patients may have been incomplete, leaving the possibility that treatment decisions were affected by unknown factors. Also, the clinics have been involved in flu research for years, which may have influenced clinician awareness of flu and prescribing practices.

Nevertheless, they said the study "adds to evidence that misuse of antibiotics, characterized by antibiotic overuse and inappropriate antibiotic selection, is widespread in the treatment of outpatient ARIs. The study indicates a number of potential targets to achieve the goal of the National Action Plan for Combating Antibiotic-Resistant Bacteria of reducing inappropriate outpatient antibiotic use by 50% by 2020."

"Increased efforts," the authors add, "are needed to support improved adherence to guidelines for antibiotic prescribing for common diagnoses, including more stringent adherence to GAS pharyngitis testing guidelines and clinical criteria for antibiotic treatment of sinusitis, as well as interventions focused on appropriate selection of first-line antibiotics for these conditions if treatment is indicated."

See also:

Jul 8 JAMA Network Open study

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