NSIH-SSI - National surveillance of surgical site infections

Last updated on 25-5-2023 by Marinka Vangenck
January 1, 2001
Project with no end date

Sciensano's project investigator(s):

In short

Surgical site infections (SSI) are infections that occur in patients who have undergone surgery and are one of the most common types of healthcare-associated infections. SSI cause additional suffering for the patient and can even lead to death in extreme cases. 
Sciensano organizes the National Surveillance of Surgical site infections to monitor their incidence in Belgium and support the prevention of SSI at local and national level.

Project summary

The European point prevalence study of healthcare-associated infections and antimicrobial use (2017) indicated for Belgium that surgical site infections (SSI) together with urinary tract infections and lung infections are the three most common types of healthcare-associated infections, with shares of 17%, 21% and 22% respectively of the total prevalence of 7.3%. 

SSI are an important cause of increased morbidity and mortality in patients undergoing surgery. Results of the National SSI Surveillance (2001–2003 results) also showed that the incidence of SSI in patients observed after hernia operations can vary from 0.8% in low-risk patients to more than 8% in high-risk patients. In the group of deep incisional or organ/cavity SSI (37% of all SSI), 34% led to re-operation and 22% to hospital readmission. The mortality rate for the group of patients with this type of SSI was also higher than that of the group that underwent the same surgery but was spared of infections. Surveillance of SSI at local and national level is therefore part of a broad strategy for the prevention of these types of healthcare-associated infections.

The national surveillance of SSI was launched in 2001 with two objectives

  1. It offers hospitals a standardized protocol and associated means for organizing surveillance within the hospital and following up on the results. 
  2. It enables national reference data concerning SSI, its risk factors and outcome parameters to be collected. This enables us to monitor the situation at national level, allowing participating hospitals to position themselves with a group of comparable hospitals or with a comparable patient population.

If a hospital participates in the national surveillance of surgical site infections

We invite general hospitals in Belgium every year to participate in the SSI surveillance on a voluntary basis. As a hospital, you can participate in the SSI surveillance as follows:

  • Select at least one surgical procedure from the list of recommended categories of operations (see the surveillance protocol below).
  • Organize the follow-up for SSI for the patients who, during the three-monthly surveillance period, have undergone the above-mentioned surgical procedures in your hospital. You can freely choose the three-monthly surveillance period; the definitions and provisions for following up the patients can be found in the surveillance protocol (available in Dutch and French).
  • You register the surveillance data via the NSIHwin software (see below) or in data files that you can create yourself (see tools) and send them to Sciensano no later than six weeks after the end of the surveillance period.

How is the data processed and what is the situation regarding confidentiality?

Hospitals provide us with the anonymized surveillance data. After an initial check, we add the submitted data to the national file. We then check whether the data is valid. Finally, we analyze the data at the individual, regional, national and European levels.

We treat individual hospital results with strict confidentiality. No information is disclosed about patient or clinician identities at any time. We only communicate individual results to the actual hospital concerned.

For the organization of SSI surveillance in the hospital, you can, as a hospital, make use of the following tools:

  • The surveillance protocol  (available in Dutch and French) contains detailed explanations of the objectives of the surveillance, the patients and surgical procedures to be followed up and the case definitions used. You will also receive an explanation about the practical organization of the surveillance and how the registrations are to be followed through.
  • The NSIHwin software (to be requested from the contact person) for the registration and follow-up of the SSI surveillance data.

The surveillance protocol contains the following annexes:

  • Reference lists (available in PDF icon Dutch and PDF icon French) containing the list of recommended surgical procedures to be registered according to coding of the National Healthcare Safety Network (NHSN), the corresponding procedure codes according to ICD9 CM coding, for each surgery category the list of cutoff values for exceeding operation times and the list of recommended markers to register for antimicrobial resistance.
  • The PDF icon data definition with a description of all the variables sought in the surveillance. This forms the basis for the registrations instructions (available in PDF icon Dutch and PDF icon French) with more explanation about the use of the data definition and the registration forms on paper or in the NSIHwin registration software. Also use the data definition as a guideline if you are creating the surveillance files directly without relying on the software.
  • Forms (available in PDF icon Dutch and PDF icon French) for paper registration.
  • An example of an individual PDF icon feedback report that is drawn up for a participating hospital after the submission of surveillance data.


The ‘Surveillance of Surgical Site Infections’ report provides an overview of the national results of the surveillance of surgical site infections (SSI) for the period from July 2001 to December 2003. As a result of the obligation imposed by the Flemish ‘Quality Decree’ of 25/02/1997, it was primarily Flemish hospitals that participated and mainly the following surgery categories that were monitored: 

  • Coronary bypass operations 
  • vascular surgery 
  • colon surgery
  • hernia repair
  • hip prosthesis
  • laminectomy 

In addition to the overall results (cumulative incidence and incidence density of SSI), we also compared the incidences per hospital. The report also includes data on, among other things, the surgery and length of stay, time between surgery and infection, surveillance after discharge and perioperative prophylactic antibiotics.

In addition, the European Center for Disease Prevention and Control (ECDC) also reports on the prevention of surgical site infections at the European level. The results are available via the ECDC’s annual reports and the ECDC’s Atlas tool (Surveillance Atlas of Infectious Diseases).

Associated Health Topics

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