Healthcare Infection Prevention – a Need for Better Aligning Research Questions with the Decisions They Inform

• Activity Number: 321 - Causal Inference in Vaccine Trials and Outbreak Investigations: Epidemiologic Study Design and Statistical Analysis
• Type: Invited
• Date/Time: Tuesday, July 30, 2019 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Justin O'Hagan*
• Companies: Centers for Disease Control and Prevention
• Keywords: transmission models; healthcare-associated infections; study design; hospitals; policy

Abstract

Contact precautions (CP) are recommended for healthcare workers caring for patients colonized or infected with methicillin-resistant Staphylococcus aureus (MRSA). Recent calls for reduced use of CP for MRSA have cited studies where increases in hospital-onset (HO) cases following discontinuation of CP were not seen. However, changes in post-discharge (i.e. community-onset, CO) disease were not considered, and the short duration of these studies means that their findings may not reflect the longer term effects of CP discontinuation. To illustrate these issues, we created a simulation of MRSA transmission in a hospital and community whereby CP use was reduced for inpatients with MRSA by 70%. We calculated HO and CO invasive MRSA cases in the 12 months before (Baseline) and after intervention (Early Intervention). We also calculated the annual number of cases occurring 10 years later, after increases in transmission in the population had plateaued (Equilibrium). The increase in HO cases in the Early Intervention period represented < 5% of the combined CO and HO increase in cases at Equilibrium. Studies in this area can substantially underestimate the number of cases averted by CP.