Validation of surgical site infection surveillance in orthopedic procedures.
BACKGROUND
Valid data are essential for a national surveillance system of nosocomial infections.


METHODS
In 8 hospitals conducting surgical site infection (SSI) surveillance for orthopedic procedures, a validation team performed a blinded retrospective chart review (10 operations with reported infections, 40 without) and interviewed infection control nurses.


RESULTS
In total, 397 patient charts were reviewed. Positive and negative predictive values for routine surveillance were 94% (95% CI: 89%-99%) and 99% (95% CI: 99%-100%), respectively. When these results were applied to the aggregated surveillance data (403 infections, 10,068 noninfections), sensitivity was 75% (95% CI: 56%-93%) and specificity 100% (95% CI: 97%-100%). The following case finding methods were used: ward visits (in 7/8 hospitals), microbiology reports (5/8), ward notifications by link nurses (8/8), and other nursing (7/8) and medical (5/8) staff. The wound culture rate ranged from 9 to 67 per 1000 patient-days. All hospitals carried out postdischarge surveillance on readmission and all but 1 at follow-up visits and by an additional questionnaire.


CONCLUSIONS
Most SSIs reported by the hospitals were true infections, showing that, when an SSI was reported, the definitions were correctly implemented. Some SSIs were missed, which might be due to weaknesses in case finding. Variation in diagnostic practices may also affect SSI rates.
Huotari
Kaisa
K
National Public Health Institute, Helsinki, Finland. kaisa.huotari@ktl.fi
Agthe
Niina
N
Lyytikäinen
Outi
O
D003428:Cross Infection / Q000517:prevention & control; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008485:Medical Audit; D019637:Orthopedic Procedures / Q000009:adverse effects* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012308:Risk Management / Q000592:standards* / Q000706:statistics & numerical data; D018571:Sentinel Surveillance; D013530:Surgical Wound Infection / Q000453:epidemiology*