Risk Factors Associated with Acute Pyelonephritis in Healthy Women

4 January 2005 | Volume 142 Issue 1 | Pages 20-27

Background: Although most cases of acute pyelonephritis occur in otherwise healthy women, data on risk factors for this condition are lacking.

Objective: To evaluate infection characteristics, incidence, and risk factors associated with acute pyelonephritis in a sample of women.

Design: Population-based case–control study.

Setting: Group Health Cooperative, a prepaid health plan in Washington.

Participants: 788 nonpregnant women, 18 to 49 years of age. Case-patients (n = 242) were women with pyelonephritis who were identified from computerized databases. Controls were 546 similar-age women with no pyelonephritis diagnosis in the previous 5 years who were randomly selected from enrollment databases. Response rates for case-patients and controls were 73% and 64%, respectively.

Measurements: Characteristics of infection and potential risk factors for pyelonephritis, ascertained through computer-assisted telephone interview and computerized databases.

Results: 7% of case-patients were hospitalized. Escherichia coli was the infecting pathogen in 85% of cases. In multivariable models, factors associated with pyelonephritis risk were frequency of sexual intercourse in the previous 30 days (odds ratio, 5.6 [95% CI, 2.8 to 11.0] for 3 times per week), recent urinary tract infection (UTI) (odds ratio, 4.4 [CI, 2.8 to 7.1]), diabetes (odds ratio, 4.1 [CI, 1.6 to 10.9]), recent incontinence (odds ratio, 3.9 [CI. 2.6 to 5.9]), new sexual partner in the previous year (odds ratio, 2.2 [CI, 1.4 to 3.6]), recent spermicide use (odds ratio, 1.7 [CI, 1.1 to 2.8]), and UTI history in the participant's mother (odds ratio, 1.6 [CI, 1.1 to 2.5]). Risk factors for selected subgroups (patients 30 years of age, patients > 30 years of age, patients with no UTI history, and inpatients) were also evaluated.

Limitations: Potential recall bias, reliance on automated case definition criteria, and limited data on diabetes and incontinence variables.

Conclusions: Few nonpregnant, community-dwelling women younger than 50 years of age with pyelonephritis are hospitalized. As with cystitis in reproductive-age women, sexual behaviors and patient and family history of UTI are associated with increased pyelonephritis risk. Diabetes and incontinence also seem to independently increase the risk for pyelonephritis.

Editors' Notes Context Little information is available about risk factors for pyelonephritis among healthy, community-dwelling women. Contribution In a population-based case-control study of women with pyelonephritis 18 to 49 years of age, intercourse history variables, including frequency, new sexual partners, and spermicide use, were strongly associated with pyelonephritis. Personal and family histories of urinary tract infection, presence of diabetes, and stress incontinence were also associated with pylonephritis on multivariable analysis. Escherichia coli was the predominant infecting organism. Implications Risk factors for pyelonephritis were similar to those for acute and recurrent cystitis and asymptomatic bacteriuria, supporting the concept that pyelonephritis is usually caused by the ascent of organisms from the bladder. –The Editors

 

Author and Article Information

From Group Health Cooperative and University of Washington, Seattle, Washington.

Acknowledgments: The authors thank the study participants and the study staff, Barbara Monsey, Jane Grafton, Margaret Farrell-Ross, Mildred Magner, Fae Neumann, Mona Varro, and Brittany Morgan, for their assistance with study protocols, study coordination, programming, data collection and management, and manuscript preparation.

Grant Support: By National Institute of Diabetes and Digestive and Kidney Diseases grants 1 PO DK53369 and K23 DK02660 (Dr. Gupta).

Potential Financial Conflicts of Interest:Consultancies: K. Gupta (Bayer Corp., Procter & Gamble, Ortho-McNeil), W.E. Stamm (Bayer Corp., Ortho-McNeil, Medimmune); Honoraria: T.M. Hooton (Bayer Pharmaceuticals), K. Gupta (Bayer Corp., Procter & Gamble, Ortho-McNeil), W.E. Stamm (Ortho-McNeil, Medimmune); Grants received: K. Gupta (Procter & Gamble).

Requests for Single Reprints: Delia Scholes, PhD, Center for Health Studies, Group Health Cooperative, 1730 Minor Avenue, 16th Floor, Seattle, WA 98101; e-mail, scholes.d{at}ghc.org.

Current Author Addresses: Dr. Scholes: Center for Health Studies, Group Health Cooperative, 1730 Minor Avenue, 16th Floor, Seattle, WA 98101.

Dr. Hooton and Ms. Roberts: Harborview Medical Center, Box 359930, 325 Ninth Avenue, Seattle, WA 98105.

Dr. Gupta: Veterans Affairs Connecticut Healthcare System, 950 Campbell Avenue, 11-ACSLG, Building 2, West Haven, CT 06516.

Drs. Stapleton and Stamm: School of Medicine, University of Washington, Box 356523, 1959 Northeast Pacific Street, Seattle, WA 98195.

Author Contributions: Conception and design: D. Scholes, T.M. Hooton, K. Gupta, A.E. Stapleton, W.E. Stamm.

Analysis and interpretation of the data: D. Scholes, T.M. Hooton, P.L. Roberts, K. Gupta, A.E. Stapleton, W.E. Stamm.

Drafting of the article: D. Scholes, T.M. Hooton, W.E. Stamm.

Critical revision of the article for important intellectual content: D. Scholes, T.M. Hooton, P.L. Roberts, K. Gupta, A.E. Stapleton, W.E. Stamm.

Final approval of the article: D. Scholes, T.M. Hooton, P.L. Roberts, A.E. Stapleton, W.E. Stamm.

Provision of study materials or patients: D. Scholes, K. Gupta.

Statistical expertise: D. Scholes, P.L. Roberts.

Obtaining of funding: D. Scholes, A.E. Stapleton, W.E. Stamm.

Administrative, technical, or logistic support: W.E. Stamm.