A Cochrane review [withdrawn from publication] included 63 trials on maxillary sinusitis. Nine studies were placebo-controlled (seven of them conducted in primary care) and 54 studies compared different classes of antibiotics. Five studies involving 631 participants comparing penicillin or amoxicillin to placebo reported clinical failure rates, which was defined as a lack of cure or improvement at 7 to 15 days follow up. For participants with symptoms lasting at least 7 days, antibiotics decreased the risk of clinical failure with a pooled RR of 0.66 (95% CI 0.47 to 0.94). However, the clinical benefit was small. Cure or improvement rate was high in both the placebo group (86%) and the antibiotic group (91%). When clinical failure was defined as a lack of total cure, antibiotics compared to placebo decreased the risk of failure with a pooled RR of 0.73 (95% CI 0.63 to 0.85) at 7 to 15 days follow up. None of the antibiotic preparations was superior to each other in head-to-head comparisons. Adverse effects in seven of the nine placebo-controlled studies (comparing penicillin, amoxicillin, azithromycin or moxicillin to placebo) were more common in antibiotic than in placebo groups (median of difference between groups 10.5%, range 2% to 23%). Drop-outs due to adverse effects were rare in both groups: 1.5% in antibiotic groups and 1% in control groups. In the 10 head-to-head comparisons, none of the antibiotic preparations were superior to another. Amoxicillin-clavulanate had significantly more drop-outs due to adverse effects than cephalosporins and macrolides.
Another meta-analysis based on individual patient data included primary care studies with a clinical diagnosis of acute sinusitis comparing an antibiotic or a placebo. Individual patients' data from 2547 adults in nine trials were checked and re-analysed. 15 patients with rhinosinusitis-like complaints would have to be given antibiotics before an additional patient was cured. Patients with purulent discharge in the pharynx took longer to cure than those without this sign; the NNT was 8 patients with this sign before one additional patient was cured. Patients who were older, reported symptoms for longer, or reported more severe symptoms also took longer to cure but were no more likely to benefit from antibiotics than other patients.