impact of firstline vs secondline antibiotics for the treatment of acute uncomplicated sinusitis context studies suggest little benefit in relief of acute sinusitis symptoms from the use of newer and more expensive secondline antibiotics instead of older and less expensive firstline antibiotics however researchers have failed to include development of complications and cost of care in their analysesobjective to compare the effectiveness and cost of firstline with secondline antibiotics for the treatment of acute uncomplicated sinusitis in adultsdesign setting and patients retrospective cohort study using a pharmaceutical database containing demographic clinical international classification of diseases ninth revision treatment and charge information for 29 102 adults with a diagnosis of acute sinusitis receiving initial antibiotic treatment between july 1 1996 and june 30 1997main outcome measures absence of additional claim for an antibiotic in the 28 days after the initial antibiotic presence of a claim for a second antibiotic serious complications of sinusitis and direct charges and use for the acute sinusitis treatmentresults there were 17 different antibiotics prescribed in this study the majority 595 of patients received 1 of the firstline antibiotics the overall success rate was 904 95 confidence interval ci 900908 the success rate for the 17 329 patients who received a firstline antibiotic was 901 and for the 11 773 patients who received a secondline antibiotic was 908 a difference of 07 95 ci 001140 p05 there were 2 cases of periorbital cellulitis one in each treatment group the average total direct charge for patients receiving a firstline antibiotic was 6898 and a secondline antibiotic was 13517 a difference of 6619 95 ci 64956743 p001 this difference was due entirely to the difference in charge of antibiotics and not other charges such as professional fees laboratory tests or emergency department visitsconclusions patients treated with a firstline antibiotic for acute uncomplicated sinusitis did not have clinically significant differences in outcomes vs those treated with a secondline antibiotic however cost of care was significantly higher for patients treated with a secondline antibiotic