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Intensive Care Medicine

, Volume 27, Issue 8, pp 1254–1262 | Cite as

Comparison of different methodological approaches to identify risk factors of nosocomial infection in intensive care units

  • Jokin de Irala-Estévez
  • Diego Martínez-Concha
  • Carmen Díaz-Molina
  • Josefa Masa-Calles
  • Amparo Serrano del Castillo
  • Rafael Fernández-Crehuet Navajas
Original article

Abstract.

Objective: Comparison of statistical methods and measurement scales to identify nosocomial infection risk factors in intensive care units (ICU). Design: Prospective study in 558 patients admitted to the ICU of a referral hospital between February and November 1994. Methods: Analysis using three logistic regression models, three standard Cox regression models, and two Cox regression models with time-dependent extrinsic factors. Different scales were used to measure exposures to risk factors (dichotomous, ordinal, quantitative, and time-dependent variables). Results: The most appropriate models were those that measured exposure using dichotomous variables. Models using ordinal or quantitative variables estimated biased coefficients and/or failed to comply with the statistical assumptions underlying the analyses. The Cox regression model with quantitative time-dependent variables met all the statistical assumptions, obtained a precise assessment of risk by exposure time, and estimated unbiased coefficients. Conclusions: The Cox regression analysis with quantitative time-dependent variables is the most valid alternative for assessing the risk of nosocomial infection per day of exposure to an extrinsic risk factor in the ICU.

Cox proportional hazards Logistic regression Intensive care units Nosocomial infections Risk factors Time-dependent variables 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Jokin de Irala-Estévez
    • 1
  • Diego Martínez-Concha
    • 2
  • Carmen Díaz-Molina
    • 2
  • Josefa Masa-Calles
    • 2
  • Amparo Serrano del Castillo
    • 3
  • Rafael Fernández-Crehuet Navajas
    • 2
  1. 1.Epidemiology and Public Health Unit, Faculty of Medicine, University of Navarre, Irunlarrea s/n, 31008 Pamplona, NavarraSpain
  2. 2.Department of Preventive Medicine, Reina Sofía University Hospital, CórdobaSpain
  3. 3.Preventive Medicine and Public Health. Faculty of Medicine, University of Cordoba, CordobaSpain

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