A 10-day course of amoxicillin "offers little clinical benefit for most patients with clinically diagnosed uncomplicated acute rhinosinusitis," the results of a placebo-controlled trial published Feb. 15 in JAMA have shown.

"Our findings support recommendations to avoid routine antibiotic treatment for patients with uncomplicated acute rhinosinusitis," according to Dr. Jane M. Garbutt and her associates at Washington University, St. Louis.

Their study involved 166 adults with a history of rhinosinusitis symptoms that had not improved, or that had worsened, for 7-28 days. Participants were randomly assigned to receive either 10 days of daily amoxicillin (85 patients) or a matching placebo (81 patients). Those who received amoxicillin reported no significant difference in symptoms at 3 days or at 10 days, compared with patients who received placebo. Some patients in the amoxicillin group were more improved at 7 days, but the difference "was too small to represent any clinically important change," the researchers wrote.

Dr. Garbutt said that this was the first trial of antibiotic therapy for rhinosinusitis that looked at disease-specific quality of life as the primary outcome. The investigators used the modified Sino-Nasal Outcome Test–16 (SNOT-16) questionnaire, which assesses both the severity and the frequency of 16 sinus-related symptoms that have bothered respondents during the past few days.

The patients were representative of those "for whom antibiotics might be prescribed" in routine practice. They were adults reporting maxillary pain or tenderness in the face or teeth and purulent nasal secretions who presented to any of 10 primary care practices in St. Louis.

In addition to amoxicillin or placebo, all patients also used as-needed acetaminophen, guaifenesin, dextromethorphan, pseudoephedrine, and nasal saline spray.

The primary end point was the effect of treatment on disease-specific quality of life at day 3, as measured by responses to the SNOT-16. "We expected any benefit of antibiotic treatment to be evident 48-72 hours after the treatment was begun," the researchers explained.

Secondary end points included the patient’s retrospective assessment of change in sinus symptoms and functional status, recurrence or relapse, and satisfaction with and adverse effects of treatment. These outcomes were assessed by telephone interview at days 3, 7, 10, and 28.

A total of 37% of the amoxicillin group and 34% of the placebo group reported symptom improvement at day 3, a nonsignificant difference. The results were similar between study groups at day 10, with 78% of the amoxicillin group and 80% of the placebo group reporting symptom improvement, the investigators said (JAMA 2012;307:685-92).

The two groups differed only at the assessment on day 7. At that time, significantly more of the amoxicillin group (74%) than of the placebo group (56%) reported symptom improvement, but the difference in scores was deemed clinically insignificant. No factor was found to predict response to amoxicillin at day 7.

When the analysis was restricted only to the 143 patients who completed their 10-day course of study treatment, the results were the same. Amoxicillin also conferred no added benefit for any subgroup of patients such as smokers, those with the longest duration of symptoms, those with a history of sinus infections, or those with asthma or allergic rhinitis.

In addition, secondary outcomes, including number of days missed from work, number of days unable to perform usual activities, rates of relapse and recurrence at 28 days, the use of additional health care services, and patient satisfaction with treatment, also were the same between patients who received amoxicillin and those who received placebo.

There were no serious adverse events, and the rates of any adverse event were the same between the two groups.

These results add to the existing "considerable body of evidence from clinical trials conducted in the primary care setting that antibiotics provide little if any benefit for patients with clinically diagnosed acute rhinosinusitis," Dr. Garbutt and her associates said.