DOES NOSOCOMIAL INFECTION NATIONAL SURVEILLANCE SCHEME DATA REFLECT THE TRUE TOTAL HIP REPLACEMENT DEEP INFECTION RATE? A CLINICAL AUDIT OF THE TELFORD EXPERIENCE

Abstract

The study aimed to determine if THR deep infection rate correlated with the Nosocomial Infection National Surveillance Scheme (NINSS) data on the surgical site infection (SSI) rate in our institution.

Deep infection is a serious complication of hip replacement but presents late. It has recently been reported that 10% of superficial infections develop deep prosthetic infections. NINSS data could therefore be used to predict a unit’s infection risk. This District General Hospital has only recently entered NINSS. In the first quarter of 2001, NINSS reported an 11.9% surgical site infection rate in THRS performed in this unit.

A clinical audit of all the primary THRs done between 1/4/94 – 9/9/2001, using revision surgery as the end point, was conducted to determine the true deep infection rate. Patients were identified using the OPCS coding system database and a casenote review was performed on all revision hip operations done locally. A search for our primary THRs that underwent revision surgery at the regional tertiary referral centre was completed to avoid omissions secondary to migration.

Of 1258 primary THRS, there were 13 revisions (1%) of which 2 were done for infection (0.16%).

NINSS data placed our unit on the 90th centile for infection risk but our historical true deep infection rate of 0.16% compares favourably with the Swedish and Trent hip registry rates of 0.58% and 1.4% respectively. We therefore urge careful interpretation of NINSS data and argue against its use in the media. The quarterly reporting of SSIs may be too short to play a role in ranking hospitals but may be helpful in prophylactic antibiotic selection.