[Use of statistical process control charts in the epidemiological surveillance of nosocomial infections].
OBJECTIVE
To monitor occurrence trends and identify clusters of nosocomial infection (NI) using statistical process control (SPC) charts.


METHODS
Between January 1998 and December 2000 nosocomial infection occurrence was evaluated in a cohort of 460 patients admitted to the Pediatric Intensive Care Unit of a university hospital, according to the concepts and criteria proposed by the National Nosocomial Infection Surveillance System of the Centers for Disease Control, in the United States. Graphs were plotted using Poisson statistical distribution, including four horizontal lines: center line (CL), upper warning limit (UWL) and upper control limit (UCL). The CL was the arithmetic mean NI rate calculated for the studied period; UWL and UCL were drawn at 2 and 3 standard deviations above average NI rates, respectively. Clusters were identified when NI rates remained above UCL.


RESULTS
Mean NI incidence was 20 per 1,000 patient days. One urinary tract infection cluster was identified in July 2000, with an infection rate of 63 per 1,000 patient days, exceeding UCL and characterizing a period of epidemic.


CONCLUSIONS
The use of SPC charts for controlling endemic levels of NI, through both global and site-specific evaluation, allowed for the identification of uncommon variations in NI rates, such as outbreaks and epidemics, and for their distinction from the natural variations observed in NI occurrence rates, without the need for calculations and hypothesis testing.
Arantes
Aglai
A
Universidade Federal de Uberlândia, Uberlândia, MG, Brasil. aglai@triang.com.br
Carvalho
Eduardo da Silva
Eda S
Medeiros
Eduardo Alexandrino Servolo
EA
Farhat
Calil Kairalla
CK
Mantese
Orlando César
OC
D000293:Adolescent; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control; D004196:Disease Outbreaks; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D017053:Infection Control / Q000379:methods*; D015278:Intensive Care Units, Pediatric; D011159:Population Surveillance; D011446:Prospective Studies; D013223:Statistics as Topic / Q000379:methods*; D014552:Urinary Tract Infections / Q000453:epidemiology / Q000517:prevention & control