Modeling Pathogen Resistance and Exposure to Antimicrobials

• Activity Number: 530
• Type: Contributed
• Date/Time: Wednesday, August 7, 2013 : 10:30 AM to 12:20 PM
• Sponsor: Biometrics Section
• Author(s): Michele Shaffer*+ and Erika D'Agata and Dan Kiely and Tonya Rosenblatt and Susan Mitchell
• Companies: Seattle Children's Research Institute and Beth Israel Deaconess Medical Center and Hebrew SeniorLife Institute for Aging Research and Hebrew SeniorLife Institute for Aging Research and Hebrew SeniorLife Institute for Aging Research
• Keywords: Discrete-time hazard models ; Nested case-control design ; Generalized estimating equations ; Random effects

Abstract

Examining the relationship between antimicrobial exposure and antimicrobial resistant bacteria (ARB) acquisition is complicated by the precision with which colonization can be measured relative to antimicrobial exposure. The Study of Pathogen Resistance and Exposure to Antimicrobials in Dementia (SPREAD) is a prospective cohort study of nursing home residents with advanced dementia. Nasal swabs and fecal specimens were obtained every 3 months for up to 12 months and cultured for the presence of methicillin-resistant Staphylococcus aurous and multidrug-resistant gram-negative bacteria. Residents entered the study either uncolonized or colonized with these ARB. Discrete-time hazard models were used to assess the association of antimicrobial exposure, expressed as days of therapy per 1000 resident-days, with ARB acquisition using the original cohort study design. Generalized estimating equations (GEE) or random effects were used to account for clustering at the nursing home level. We present the results and limitations of sensitivity analyses used to examine the association between antimicrobial exposure and acquisition of one or more ARB including use of a nested case-control design.