INTEROBSERVER RELIABILITY OF THE DIAGNOSTIC CRITERIA FOR SUPERFICIAL INCISIONAL INFECTION

Abstract

The Department of Health and the Public Health Laboratory Service established the Nosocomial Infection National Surveillance Scheme (NINSS) in response to the need to standardise the collection of information about infections acquired in hospital. This would provide national data that could be used as a ‘benchmark’ by hospitals to measure their own performance. The definition of superficial incisional infection (skin and subcutaneous tissue), set by Centers of Disease Control (CDC), should meet at least one of the following criteria: I: Purulent drainage from the superficial incision. II: The superficial incision yields organisms from the culture of aseptically aspirated fluid or tissue, or from a swab, and pus cells are present. III: At least two of the following symptoms and signs of inflammation: pain or tenderness, localized swelling, redness or heat, and a. the superficial incision is deliberately opened by a surgeon to manage the infection, unless the incision is culture-negative or b. clinician’s diagnosis of superficial incisional infection.

This study assessed the interobserver reliability of the superficial incisional infection criteria, set by the CDC, in current practice.

The incisional site of 50 consecutive patients, who underwent elective primary joint arthroplasty (Hips & Knees), were evaluated independently by four observers. The most significant results of the study I: All four observers achieved absolute agreement (kappa=1) for Purulent wound discharge and clinical diagnosis of wound infection. II: The four observers obtained good agreement for pain criteria (kappa=0.76, III: There was significant disagreement (fair to poor) between all four observers for the following criteria: Localized swelling (kappa=0.34), Redness (kappa=0.33) and tenderness (kappa = 0.05).

This is the first study to assess the reliability of the criteria, as set by the CDC and recommended by NINSS, for the diagnosis of superficial incisional infection and shows the Criterion III is not reliable and we recommend it should be revised. Failure to do so could lead to inaccurate statistics regarding hospital wound infection and detrimental effect on hospital trusts in the setting of league table.