Comparison of Prevalence Calculations Using Infection Control Surveillance Methods and Cystic Fibrosis Foundation Patient Registry Guidelines

Abstract

BACKGROUND: In May 2003, the consensus document was published entitled, Infection Control Recommendations for Patients with Cystic Fibrosis (CF): Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmission. The recommendations are based on the basic principle that CF pathogens are transmitted by the droplet and contact routes. The CF Foundation Patient Registry (CFFPR) compiles and publishes the age-specific prevalence of respiratory pathogens in CF patients each year. Our CF Center participates in this registry and uses the data to compare our pathogen-specific prevalence with national data. Discrepancies were found when comparing our data with those from the CFFPR due to difference in the methods of calculating prevalence. OBJECTIVE: To understand how different methods of analysis might influence the interpretation of center-specific, as compared to national registry, infection control data. METHODS: The Department of Infection Prevention and Control at Children's Hospital of Philadelphia (CHOP), in collaboration with the CHOP Cystic Fibrosis Center, conducts active surveillance of cystic fibrosis patients for Burkholderia cepacia (BC) and methicillin-resistant Staphylococcus aureus (MRSA). Traditionally, prevalence data at our institution were reported based on the number of patients ever colonized with BC or MRSA (termed IPC prevalence). Upon review of CFFPR reporting guidelines, we calculated the period prevalence of colonization based on isolation of BC or MRSA within the past calendar year (termed CFFPR prevalence) and stratified our data by age group. RESULTS: Comparison of IPC and CFFPR prevalence revealed discrepant results. For active patients in the CHOP CF Center, IPC prevalence of MRSA was 10.0%. However, the prevalence of MRSA as determined by CFFPR reporting guidelines was markedly lower; CFFR prevalence was 5.5%. In contrast, IPC prevalence of BC was 7.4%, while CFFPR prevalence was 6.7%. Consistent with national data, we observed higher prevalence of these two critical pathogens was observed in the 11–17 and 18–24 age groups compared to younger age groups. CONCLUSIONS: Caution is needed when comparing data from national registries with data collected by infection control departments within individual centers. Differences in collecting and reporting data to the CF Foundation from traditional infection control surveillance methods must be fully appreciated by those using these data for benchmarking purposes.