Kidney function and the use of nitrofurantoin to treat urinary tract infections in older women.
BACKGROUND
The antibiotic nitrofurantoin is commonly used to treat uncomplicated urinary tract infections. However, when this drug is used by patients with reduced kidney function, its urine concentration may be subtherapeutic.


METHODS
We conducted a population-based study of older women (mean age 79 years) in Ontario, Canada, whose estimated glomerular filtration rate was relatively low (median 38 mL/min per 1.73 m(2)) and for whom 1 of 4 antibiotics had been prescribed for urinary tract infection: nitrofurantoin, ciprofloxacin, norfloxacin or trimethoprim-sulfamethoxazole. We assessed 2 measures of treatment failure in the subsequent 14 days: receipt of a second antibiotic indicated for urinary tract infection and hospital encounter (emergency department visit or hospital admission) with a urinary tract infection. We repeated the analysis for older women with relatively high estimated glomerular filtration rate (median 69 mL/min per 1.73 m(2)).


RESULTS
The baseline characteristics of the 4 antibiotic groups were similar. Relative to nitrofurantoin, the other antibiotics (including ciprofloxacin) were associated with a lower rate of treatment failure among women with relatively low estimated glomerular filtration rate (for ciprofloxacin v. nitrofurantoin: second antibiotic prescription, 130/1989 [6.5%] v. 516/3739 [13.8%], odds ratio [OR] 0.44, 95% confidence interval [CI] 0.36-0.53; hospital encounter, 21/1989 [1.1%] v. 95/3739 [2.5%], OR 0.41, 95% CI 0.25-0.66). However, a similar risk of treatment failure with nitrofurantoin was also observed among women with relatively high estimated glomerular filtration rate. The results were consistent in multiple additional analyses.


CONCLUSIONS
In this study, the presence of mild or moderate reductions in estimated glomerular filtration rate did not justify avoidance of nitrofurantoin.
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Namisha
N
Singh
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Sonja
S
Gandhi
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Eric
E
McArthur
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Louise
L
Moist
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Arsh K
AK
Jain
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Aiden R
AR
Liu
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont.
Manish M
MM
Sood
Division of Nephrology, Department of Medicine (Singh, Gandhi, McArthur, Moist, Jain, Liu, Garg), and the Department of Epidemiology and Biostatistics (Gandhi, Moist, Liu, Garg), Western University, London, Ont.; Institute for Clinical Evaluative Sciences (McArthur, Moist, Jain, Garg), Toronto, Ont.; The Ottawa Hospital Research Institute (Sood), University of Ottawa, Ottawa, Ont. amit.garg@lhsc.on.ca.
Amit X
AX
Garg
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000892:Anti-Infective Agents, Urinary / Q000627:therapeutic use*; D002939:Ciprofloxacin / Q000627:therapeutic use; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D009582:Nitrofurantoin / Q000627:therapeutic use*; D009643:Norfloxacin / Q000627:therapeutic use; D051437:Renal Insufficiency / Q000150:complications*; D012189:Retrospective Studies; D012737:Sex Factors; D017211:Treatment Failure; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use; D014552:Urinary Tract Infections / Q000150:complications / Q000188:drug therapy*
D000900:Anti-Bacterial Agents; D000892:Anti-Infective Agents, Urinary; D002939:Ciprofloxacin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D009582:Nitrofurantoin; D009643:Norfloxacin