Vol. 23 No. 3 INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY 133 THE ROLE OF NURSE UNDERSTAFFING IN NOSOCOMIAL VIRAL GASTROINTESTINAL INFECTIONS ON A GENERAL PEDIATRICS W ARD Jacob Stegenga, BA; Erica Bell, MA; Anne Matlow, MD, FRCPC OBJECTIVE: To examine the relationship between nurse staffing levels and the rate of nosocomial viral gastrointestinal infections (NVGIs) in a general pediatrics population. DESIGN: Retrospective descriptive study. SETTING: A general pediatrics ward at The Hospital for Sick Children in Toronto, Ontario, Canada, a 320-bed, tertiary-care pediatric institution. RESULTS: Forty-three NVGIs were detected in 37 patients of 2,929 admissions (1.3%). The monthly NVGI rate correlated sig- nificantly with the monthly night patient-to-nurse ratio (r = 0.56) and the monthly day patient-to-nurse ratio (r = 0.50). The nursing hours per patient-day during the preinfection period (PIP) were significantly lower than those during the nonpreinfection period (NPIP; 12.5 vs 13.0). There was no difference between the PIP and the NPIP day patient-to-nurse ratios (3.31 vs 3.32), but there was a significant difference between the PIP and the NPIP night patient- to-nurse ratios (3.26 vs 3.16). The incidence of NVGIs in the 72- hour period after any day when the nursing hours per patient-day were less than 10.5 was 6.39 infections per 1,000 patient-days, com- pared with 2.17 infections per 1,000 patient-days in periods with more than 10.5 nursing hours per patient-day (rate ratio, 2.94; 95% confidence interval, 2.16 to 4.01). CONCLUSION: Nurse understaffing contributed to an increased NVGI rate in our general pediatrics population, and should be assessed as a risk factor in outbreak investigations (Infect Control Hosp Epidemiol 2002;23:133-136). In recent years, an association has begun to emerge between understaffing and nosocomial infection rates. Haley and Bregman first identified understaffing as a poten- tial risk factor for nosocomial staphylococcal infections in a neonatal special-care unit. 1 Since then, nurse understaffing has been identified as a risk factor for other nosocomial infections, including 2 central venous catheter–associated bloodstream infections 3,4 ; for an increased nosocomial infec- tion rate in a pediatric cardiac intensive care unit 5 ; for uri- nary tract infections and pneumonia after surgery in an adult population 6 ; and for an outbreak of Enterobacter cloa- cae infection in a neonatal intensive care unit. 7 One study found no relationship between nursing workload and colo- nization with vancomycin-resistant enterococci. 8 A recent surge in the incidence of nosocomial viral gastrointestinal infections (NVGIs) on our general pedi- atrics ward prompted us to evaluate whether there was an association between nurse staffing levels and NVGIs in this patient population. METHODS The Hospital for Sick Children in Toronto, Ontario, Canada, is a 320-bed, tertiary-care pediatric institution. The study locale was a 44-bed general pediatrics ward com- posed mainly of single rooms. A retrospective review of administrative, patient ward, and laboratory data was con- ducted for the period December 1997 through March 1999 (the study period). During the study period, stool samples were ordered by the attending physicians as clinically indi- cated to rule out viral gastroenteritis and were submitted to the virology laboratory for examination by electron microscopy. NVGI was defined according to Centers for Disease Control and Prevention definitions of nosocomial infections. 9 The NVGI rate was defined as the number of NVGIs per 1,000 patient-days. Analysis For each day of the study period, the number of nurs- ing hours and the patient census were determined from a retrospective review of administrative and patient records. Nurse staffing levels were calculated in two ways: patient- to-nurse ratio and nursing hours per patient-day. Patient-to- nurse ratio was obtained from nurse records and was exam- ined by day shift (7:30 am to 7:30 pm) and night shift (7:30 pm to 7:30 am), according to the actual work schedule on the ward. The nursing hours included educational hours Mr. Stegenga, Ms. Bell, and Dr. Matlow are from the Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario, Canada. Dr. Matlow is also from the Department of Pediatric and Laboratory Medicine, The Hospital for Sick Children; and the Departments of Pediatrics and Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada. Address reprint requests to Dr. Anne Matlow, Director, Infection Prevention and Control Program, The Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8 Ontario, Canada. ABSTRACT