title: Incidence of surgical site infections cannot be derived reliably from point prevalence survey data in Dutch hospitals.
abstract: Thorough studies on whether point prevalence surveys of healthcare-associated infections (HAIs) can be used to reliably estimate incidence of surgical site infections (SSIs) are scarce. We examined this topic using surveillance data of 58 hospitals that participated in two Dutch national surveillances; HAI prevalence and SSI incidence surveillance, respectively. First, we simulated daily prevalences of SSIs from incidence data. Subsequently, Rhame & Sudderth's formula was used to estimate SSI incidence from prevalence. Finally, we developed random-effects models to predict SSI incidence from prevalence and other relevant variables. The prevalences simulated from incidence data indicated that daily prevalence varied greatly. Incidences calculated with Rhame & Sudderth's formula often had values below zero, due to the large number of SSIs occurring post-discharge. Excluding these SSIs, still resulted in poor correlation between calculated and observed incidence. The two models best predicting total incidence and incidence during initial hospital stay both performed poorly (proportion of explained variance of 0·25 and 0·10, respectively). In conclusion, incidence of SSIs cannot be reliably estimated from point prevalence data in Dutch hospitals by any of the applied methods. We therefore conclude that prevalence surveys are not a useful measure to give reliable insight into incidence of SSIs.
authors.affiliation: Centre for Infectious Disease Control,Department of Epidemiology and Surveillance,National Institute of Public Health and the Environment (RIVM),Bilthoven,The Netherlands.
authors.forename: A P
authors.initials: AP
authors.lastname: Meijs
authors.affiliation: Department of Statistics,Informatics and Modelling,National Institute of Public Health and the Environment (RIVM),Bilthoven,The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Ferreira
authors.affiliation: Centre for Infectious Disease Control,Department of Epidemiology and Surveillance,National Institute of Public Health and the Environment (RIVM),Bilthoven,The Netherlands.
authors.forename: S C
authors.initials: SC
authors.lastname: DE Greeff
authors.affiliation: Department of Medical Microbiology and Infectious Diseases,Erasmus MC,Rotterdam,The Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Vos
authors.affiliation: Centre for Infectious Disease Control,Department of Epidemiology and Surveillance,National Institute of Public Health and the Environment (RIVM),Bilthoven,The Netherlands.
authors.forename: M B G
authors.initials: MB
authors.lastname: Koek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D056808:Biostatistics / Q000379:methods; D002648:Child; D002675:Child, Preschool; D004812:Epidemiologic Methods; D005260:Female; D006761:Hospitals; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D013530:Surgical Wound Infection / Q000453:epidemiology*; D055815:Young Adult
keywords: Incidence; prevalence; surgical site infections; surveillance