Yet again, another article that saturated the lay press due to its publication in JAMA – this time regarding amoxicillin for acute sinusitis.
The problem is, I agree with the fundamental point the authors are making – according to the introduction, antibiotics for sinusitis account for 1 in 5 antibiotic prescriptions in the United States and they’re typically unnecessary, especially in an era where better antibiotic stewardship is needed. However, I cannot imagine how a multicenter study of ten community clinics in St. Louis over three years only managed to enroll 166 adults into this study over the course of three years. Their recruitment diagram states only 244 patients were assessed for eligibility – which seems like it ought to be a a couple months worth of URI presentations in an outpatient setting.
If you read the newspaper, you already know the main results – “no difference between 10 days of amoxicillin and placebo.” But 11 of 85 intervention group patients discontinued treatment, as well of 12 of 81 placebo patients. Due to lost data, 4 of 85 intervention patients were excluded from analysis, as well as 7 of 81 placebo patients. Then, 32% of patients in the intervention group were non-compliant with the intervention – so, while this is valid in a real-world effectiveness sense, they’re increasingly no longer relevant to the actual efficacy of the intervention. These are big holes in a small study.
And, bizarrely, the baseline characteristics they use to describe the two groups include more social characteristics than clinical characteristics – healthcare insurance, family income, etc. Children living in the home, children in day care, etc., is an interesting demographic criteria, suggesting unique infectious exposure – 9% more intervention group patients had children at home, but this isn’t statistically significant because the sample sizes are so tiny. Then, the clinical characteristics they chose only seem to partially reflect issues relevant to antibiotic efficacy – “usual health excellent or good” isn’t a very useful descriptor of whether they have impaired baseline immune function that places them at increased risk of significant bacterial superinfection. For what it’s worth, the control group was significantly “healthier”, but also had significantly more smoking history.
Getting back to the main results – yes, the average SNOT-16 scores were equal at day 0, 3 and 10, but favored the intervention at day 7 – leading to their final conclusion that amoxicillin was of no benefit. But, at the individual patient level, the control group patients were impaired from their usual activities almost 50% longer – 1.67 days vs. 1.15 days, and there was a 12% absolute difference in satisfaction with treatment favoring the intervention – 53% vs. 41 %. But, due to the tiny sample size, none of these differences reached statistical significance.
In the end, it’s a fair real-world trial and addition to the literature, but it’s far too small and flawed a trial to stand on to as evidence.
Oddly, one of the authors receives royalties for the SNOT-16 scale.
“Amoxicillin for Acute Rhinosinusitis: A Randomized Controlled Trial”
http://jama.ama-assn.org/content/307/7/685