National patterns in the treatment of urinary tract infections in women by ambulatory care physicians.

BACKGROUND

Trimethoprim-sulfamethoxazole has consistently been the recommended drug for uncomplicated urinary tract infections in women. Which antibiotics physicians use has implications for patient outcomes, antimicrobial resistance, and costs.

METHODS

This study was based on a sample survey of practicing physicians participating in the National Ambulatory Medical Care Survey from 1989 through 1998. Eligible visits were limited to those by women aged 18 to 75 years diagnosed with uncomplicated acute cystitis or urinary tract infection (N = 1478). We evaluated trends in the proportions of visits at which physicians prescribed (1) trimethoprim-sulfamethoxazole, (2) recommended fluoroquinolones, (3) nitrofurantoin, and (4) nonrecommended antibiotics (neither trimethoprim-sulfamethoxazole nor recommended fluoroquinolones). We also identified predictors of specific antibiotic prescribing among visits to primary care physicians.

RESULTS

The most frequently prescribed antibiotics were trimethoprim-sulfamethoxazole, recommended fluoroquinolones, and nitrofurantoin. We found that the proportion of trimethoprim-sulfamethoxazole prescriptions declined from 48% in 1989-1990 to 24% in 1997-1998 (adjusted odds ratio [OR], 0.33; 95% confidence interval [CI], 0.21-0.52 per decade). Conversely, fluoroquinolone use increased (19% to 29%) (OR, 2.28; 95% CI, 1.35-3.83) as did nitrofurantoin prescribing (14% to 30%) (OR, 2.44; 95% CI, 1.44-4.13). Among primary care physicians, internists were the most likely to prescribe fluoroquinolones while obstetricians were the most likely to use nitrofurantoin.

CONCLUSIONS

Ambulatory care physicians are increasing their use of fluoroquinolones and nitrofurantoin, even though they are not highly recommended and not the most cost-effective. Antibiotic prescribing in urinary tract infections may be influenced by clinical factors such as pregnancy and drug allergies but may also be shaped by nonclinical factors such as subspecialty culture.