How do national and international surveillance techniques impact infection control?

Surveillance is the continuous and systematic process of collection, analysis, interpretation and dissemination of descriptive information for monitoring health problems. The Study of Efficacy of Nosocomial Infection Control (SENIC) was a nationwide project that demonstrated for the first time that surveillance and the dissemination of its results is the single most important factor to reduce nosocomial infections involving the four major sites (urinary tract infection, surgical site infection, pneumonia, and bacteremia).

The results of the SENIC project represented a major boost to the development of the National Nosocomial Infection Surveillance System (NNIS) in the United States, which is the oldest, the best developed, and which has been the model for many other national surveillance systems. Since the nineties, several countries have established surveillance systems for nosocomial infections on national basis that in many cases share similarities with NNIS. Numerous studies have demonstrated that infection control programs which are based on surveillance are not only effective but also cost-effective on reducing healthcare-associated infections (HAI).

Surveillance of nosocomial infections is currently essential for infection control because:

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  • Surveillance itself improves the outcomes in the prevention and control of HAI

  • It is the indispensable baseline to detect new problems

  • It allows interventions to be prioritized to improve the quality of care

  • It permits the impact of any measure designed to reduce HAI to be measured

Surveillance systems are networks of hospitals normally in a geographic area that have agreed to conduct surveillance in the same way with a centralized data collection and a common analysis of the data. This method permits them:

  • To establish benchmarks for the different rates of HAI

  • To make comparisons of the outcomes between hospitals and these comparisons can stimulate new interventions to reduce the rates and can also promote collaboration between hospitals to design multicenter interventions

  • Aggregate results can be used by health authorities to plan and prioritize public health actions and also to measure the impact of these actions

What elements of national and international surveillance are necessary for infection prevention and control?

The key elements of any surveillance system that need to be adhered to are:

  • Case definition: The definitions of HAI must be standardized, must be easy to apply and must be uniform across all institutions. It is important to assess periodically the accuracy and the consistency with which definitions are applied. Many different national systems use the NHSN (National Healthcare Safety Network – CDC USA) definitions.

  • Methods for case ascertainment: The methods to identify the cases that are candidates for surveillance of a particular type of infection and the way of monitoring them to detect the possible occurrence of an infection must be clearly delineated and have to be uniform over time and among all the participant hospitals.

  • Risk adjustment: No comparison can be made if data are not previously adjusted by major confounders and this makes it compulsory that the methods to stratify by risk have to be exactly the same throughout the network.

  • The data collection has to be accurate and reliable.

  • Results of surveillance must be disseminated to the hospital staff members who will participate in prevention and control of HAI.

It is also important to maintain the three first criteria as stable as possible to permit the trends of the nosocomial infections to be assessed over time. However, some modifications have had to be incorporated. For example: the new definition of organ-space infection associated with prosthetic knee surgery, the ventilator associated pneumonia and catheter urinary infection definitions, or the change in surveillance time in all the prosthetic surgeries that recently has changed from 1 year to 90 days surveillance in the majority of the surveillance systems. The date of these modifications in each system is important to compare rates and to evaluate trends over time.

What are the consequences of ignoring national and international surveillance techniques?

If surveillance techniques in a network are not previously agreed or if they are used inconsistently, variations will occur in the sensitivity and specificity for HAI case-finding and the main objectives of the surveillance system will be severely compromised:

  • The endemic rates and trends will not be reliable and the capacities of the system to measure the efficacy of the infection control programs and to detect outbreaks will be severely hampered.

  • Interhospital comparisons of infection rates can be meaningless or misleading.

  • Benchmarking will be not possible.

  • Comparisons of the aggregate rates between different national systems will be useless.

  • If case-mix adjustment is lacking, HAI rates will be misleading and comparison between hospitals or countries cannot be made.

What other information supports the research on national and international surveillance techniques?

Numerous studies have demonstrated the efficacy of surveillance to prevent HAI. The basic principles of this knowledge have led to:

  • The professional association that bring together most of infection preventionists has published and updated practical recommendations on the methodology to carry out HAI surveillance based on these scientific principles.

  • Scientific societies have incorporated to their evidence-based clinical guidelines for prevention of HAI, the key recommendations on surveillance for each HAI.

  • Public health government agencies and also supranational agencies have published recommendations for individual institutions and also for local health authorities with the main requirements on HAI surveillance that they should meet.

  • Accreditation Agencies have incorporated into their programs the requirements that institutions must comply with on HAI surveillance to pass the accreditation process.

  • Many states in the USA and several countries have made specific laws for mandatory reporting of the surveillance results of some HAI.

Summary of current controversies regarding national and international surveillance techniques.

  • Efficacy and efficiency of HAI surveillance systems were demonstrated in inpatient populations in acute care settings and now a large part of healthcare takes place on an ambulatory basis or directly outside hospitals and is unknown if these principles are still valid for the same HAI in this new situation.

  • In reference to the techniques used by the surveillance systems:

    Surveillance methodology of some HAI lacks a gold standard.

    Case ascertainment is more difficult to harmonize in outpatient surgery.

    An optimal way to do post-discharge surveillance has not been established.

    Best method and frequency to disseminate results within the organizations are unknown.

    Systems lack a standardized mechanism to monitor reliability and validity of their data.

    We lack randomized trials to test the efficiency of hospital-wide versus target surveillance.

  • In reference to target surveillance:

    There is not a minimum set of recommended indicators for surveillance.

    Lack of agreement on which are the best recommended HAI to monitor in each institution.

    Some components of the targeted surveillance systems lack information on their efficiency.

  • In reference to the organization of national and international surveillance systems:

    There is a need for robust national or international protocol to obtain comparable and unbiased data.

    There is no agreement on the minimum national standards of surveillance that every country must achieve.

    Comparison of indicators with historical benchmarks is frequently difficult. because institutions regularly join and leave the networks or do not always report the same indicators.

    The changes in infections definitions and surveillance methods have not been introduced simultaneously in all the different national surveillance systems.

    Remains controversial whether participation in surveillance systems should be voluntary or mandatory.

    Some principles of surveillance that were designed for voluntary and confidential systems are not valid for mandatory systems with public results.

    It is unknown whether to publish the results is more or less efficient than to maintain them confidential.

  • The effect of penalties or rewards linked to participation in the surveillance systems or linked to the performance results is unknown.

What is the impact of national and international surveillance techniques relative to the impact of other aspects of infection control?

The development of surveillance systems and the evidence that control program infections are capable of reducing the incidence of HAI has led to a series of new facts in the field of infection control:

  • In many US states and in several countries surveillance has become a mandatory instrument for HAI control and in many cases the HAI rates are disclosed to the public.

  • The obligation to report HAI rates has shown some weaknesses of the system especially for setting benchmarks and for comparisons between institutions, particularly with some indicators, such as ventilation-associated pneumonia.

  • Surveillance systems and infection control programs have become an essential part of patient safety culture and are mandatory elements for the accreditation of the hospitals.

  • The fact that Medicare has decided not to pay for certain hospital-acquired infections, has forced institutions to invest in the development and improvement of surveillance systems and in programs for infection control.

Nevertheless, mandatory and public reporting has many methodological issues that are still unresolved but is there a risk of changing the original objectives of HAI surveillance. In mandatory reporting, to detect less HAI can be economically advantageous for the institutions and this fact can pervert the original objective of surveillance. The need that hospitals have of obtaining good results within the system can switch the prioritization of the surveillance efforts to satisfying the requirements of the systems, instead of solving their most important problems.

Outcome indicators that are difficult to measure and to compare are likely to be abandoned, independently of the magnitude of the clinical problem that they measure, just because of the intrinsic difficulty for their application and analysis. Public mandatory systems have an imperative need to find indicators easier to apply and to compare, and this means that some surveillance systems are increasing the proportion of process or structure indicators which do not require risk adjustment, in detriment of outcome measures which have traditionally been the main indicators in surveillance systems designed to control infection.

Accreditation agencies, such as JAHCO have similar problems to the mandatory reporting systems to perform their duties. The problems of measurement and comparison of some outcome indicators have made them choose more process, infrastructure and performance requirements. In its last edition outcome indicators are limited to catheter-associated bacteremia, the incidence of MDRO and surgical site infections. The need for institutions to comply with the requirements of the JAHCO may determine that infection control programs cannot be well adapted to the real needs of the institutions.

The decision of Medicare to no longer paying for some potentially preventable HAI may somehow also be changing the rules. This policy which was aimed at increasing the efforts of institutions in HAI prevention can on the contrary favor low-risk activities and may switch the way in which the search for or the coding of HAI is carried out and can lead to underreporting.

Overview of the important clinical trials, meta-analyses, case control studies, case series, and individual case reports related to infection control and national and international surveillance.

See Table I for a summary of relevant research regarding the HAI national surveillance systems.

Table I.
First author Year of publication Country System Indicators Setting Objectives Main outcomes
Haley 1985 USA NNIS SENIC project 1970-1976 BSI, pneumonia, UTI, & SSI Random sample 338 acute care hospitals > beds Effectiveness of surveillance and infection control programs 32% HAI reduction
Jarvis 1991 USA NNIS 1986-1990 BSI, UTI & VAP 179 adult & pediatric ICU from 79 hospitals Determine best denominator in ICU indicators Device days and ICU type to stratify ICU rates
Mertens 1994 Belgium and Netherlands 1991-1992 SSI 35 Dutch and 62 Belgian hospitals Comparing national rates Need harmonization between national networks
Gaynes 1996 USA NISS1986-1994 BSI, pneumonia, GI. Microbiological etiology of HAIs 99 HRN Descriptive epidemiology of HAI in HRN BSI most frequent HAI, CNS most frequent pathogen
Ronveaux 1996 Belgian Belgian network 1992-1993 SSI 51 hospitals Descriptive epidemiology & % antibiotic prophylaxis Improtance of post discharge surveillance in SSI & antibiotic prophylaxis as process indicator
Richards 1999 USA NNIS1992-1997 BSI, pneumonia & UTI 61 pediatric ICUs Descriptive epidemiology of pediatric ICU 1st – BSI, CNS2nd – Pneu, pseudomonas3rd – UTI, E.coli
CDC 2000 USA NNIS1990-1999 BSI, VAP & UTI in ICU 405 adults & 73 pediatric ICUs Descriptive epidemiology Reduction of BSI, VAP & UTI rates
Richards 2000 USA NNIS1992-1998 VAP, BSI & UTI 205 combined medical-surgical ICU Descriptive epidemiology 1st – VAP, S aureus2nd – UTI, E. coli3rd – BSI, CNS
Geubbels 2000 Netherlands PREZIES1996-1997 SSI 38 hospitals Descriptive epidemiology SSI rates for 16 procedures
Gaynes 2001 USA NNIS1992-1998 SSI 225 hospitals Use of risk index, influence of laparoscope in risk NNIS surgical risk index usefulness.Incorporation of laparoscope to risk index in four procedures
NNIS 2003 USA NNIS1992-2003ICARE/AUR ICU device associated indicators, SSI,antimicrobial resistant pathogen in ICUs,antimicrobials usage in DDD ICU, HRN, surgical procedures Descriptive epidemiology Lower SSI when laparoscope; resistance rates higher in ICUs
NNIS 2004 USA NNIS1992-2004ICARE SSI, antimicrobial resistant pathogen in ICUs, antimicrobials in DDD ICU, HRN, surgical procedures Descriptive epidemiology 60% of MRSA40% of Klebsiella resistant to 3rd generation cephalosporins
Gastmeier 2006 Germany KISS1997-2003 CR-BSI, VAP in ICUsSSI 150 ICU133 surgical departments Effectiveness of nationwide surveillance system Significant reduction in CR-BSI, VAP & SSI
Brandt 2006 Germany KISS1997-2004 SSI 133 surgical departments Effectiveness of SSI surveillance Reduction in SSI rates
Schwab 2007 Germany NEO-KISS2000-2005 BSI & pneumonia 24 NICU Effectiveness of surveillance in NICU BSI reduction
Mannien 2007 Germany PREZIES1999-2004 SSI 40 hospitals Validation study of the surveillance system Positive predictive value 0.97Negative predictive value 0.99
Klevens 2008 USA NHSN2006 BSI 32 outpatients dialysis centers Descriptive epidemiology of BSI in dialysis BSI rates in relation with fistulas, grafts, permanent & temporary catheters
Geffers 2008 Germany NEO-KISS2000-2005 BSI, pneumonia, necrotizing enterocolitis 52 NICU Descriptive epidemiology of HAI in < 1,500g infants BSI, pneumonia and enterocolitis rates
Wilson 2008 England SSISS2004-2005 Hip replacement SSI 125 hospitals Way to identify poor performing hospitals Funnel plots of rates improves accuracy
Szilagyi 2009 Hungary NNSR2004-2006 SSI 41 hospitals Descriptive epidemiology Comparative data of NNSR versus NNIS
Gastmeier 2009 Germany KISS2007 C. difficile associated diarrhea 34 hospitals Descriptive epidemiology 46.5 CDAD/10,000 admissions73% nosocomial
Astagneau 2009 France ISO-RAISIN1999-2006 SSI 838 hospitals Effectiveness of surveillance in SSI SSI rates reduction
Edwards 2009 USA NHSN2006-2008 BSI, CAUTI, VAP in ICUs, NICUsSSI 1,545 hospitals Descriptive epidemiology:Effects of mandatory reporting in 11states & enrollment od < 100 beds hospitals BSI reductionNICU rates reductionNo differences between states with and without mandatory reporting
Gravel 2009 Canada Canadian Nosocomial Surveillance System2004-2005 HAI C. difficile infection 29 hospitals Descriptive epidemiology No changes in incidence, great variability among hospitals
Zuschneid 2010 Germany ICUs in Germany CR-BSI, VAP & CAUTI in ICUs 50 ICU Validation study on representativeness of KISS ICU sample Agreement between study group and KISS group
Simor 2010 Canada Canadian Nosocomial Surveillance System1195-2007 MRSA incidence 48 hospitals Descriptive epidemiology Increase of nosocomial and community MRSA
Huotari 2010 Finland Finnish Hospital Infection Program(SIRO)1999-2004 Hip and knee replacement SSI 12 hospitals Validation study of the surveillance system Rates higher than previously published
Berg 2011 Norway NOIS2005-2009 CABG-SSI 6 hospitals Descriptive epidemiology of CABG-SSI in a mandatory reporting system No reduction
Viseur 2011 Belgium Belgian network2008-2010 Mandatory report of CDAD 150 hospitals Descriptive epidemiology of CDAD in a mandatory system Decrease of incidenceDecrease of % of CD ribotype 027
Mu 2011 USA NHSH2006-2008 SSI 847 hospitals New risk adjustment

New risk models increases predictive performance

Controversies in detail.

On the techniques of surveillance

Since the SENIC project published it results, other cohort studies have demonstrated the effectiveness and also the efficiency of HAI surveillance systems. All these studies were performed in hospitals and with inpatient populations. Since that time the great majority of hospitals have significantly reduced their hospital stays and many inpatient procedures have become ambulatory. These facts have a radical importance in the surveillance of some indicators such as surgical site infection. As the length of stays decreases the way to ascertain the cases is more difficult because most HAI will appear after hospital discharge. Unfortunately we lack a standard for post-discharge surveillance methodology because the way to perform this duty is very hospital-dependent. This change produces a tendency to under-diagnose surgical site infections and can hinder the comparison not only with historical rates, but also with other hospitals and also in the case of aggregate data can preclude comparison between different systems.

In 2013 NHSN changed 1 year surveillance in prosthetic surgeries to 90 days-surveillance. This change, which implies a lower sensitivity to the detect related infections has been accepted in most surveillance systems. The reasons that support this change are: the decrease of surveillance workload that allows to increase the ICP time to implement preventive measures, and also because the greater immediacy for feedback to surgeons. The simultaneous improvement in post-discharge surveillance methods has shown that the lower sensitivity is acceptable and the measure can be efficient.

The situation has become even more complicated in the era of outpatient major surgery in which patients come to hospital only for the intervention and the rest of their follow-up is done in other outpatient healthcare units. This circumstance has not only influence the methodology to ascertain the cases but also the way to apply the diagnostic criteria of HAI. The healthcare facilities where continuity of care is better ensured and which share their electronic medical records along the entire care process are more likely to conduct surveillance in a manner more similar to what is still considered the surveillance standard.

Moreover, in addition to the migration, which occurred in the last two decades of the acute care of patients from inpatient wards to ambulatory care units, another phenomenon is happening at the same time. Many patients who some years ago were considered “acute patients” and admitted to acute care facilities are being sent to short-term rehabilitation centers, nursing homes, home-care or long-term facilities. This fact prevents the comparison of acute care centers with their own historical data. The different organizational structures, the heterogeneity of patients and often the limited resources in these “non acute care” facilities have had to change the rules on HAI surveillance for these patients. Recently SHEA and APIC, published guidelines for conducting infection control and surveillance of HAI in these facilities but results on efficiency and effectiveness are still unknown.

On the methodology of surveillance systems

It is well known that to harmonize the methodology of surveillance is the cornerstone of any surveillance system to permit comparisons over time and between centers. The overall strength of the techniques for HAI surveillance is well demonstrated but there are some gaps which remain controversial.

In reference to case definition, despite efforts over the last 25 years to standardize the diagnostic criteria of HAIs, difficulties remain to implement some of them. Thus, the diagnostic criteria of ventilation-associated pneumonia, of catheter-associated urinary infection and some of the criteria that we use to define surgical site infections have a margin for subjectivity, which means that the sensitivity and specificity can be influenced by the observer. New definitions such as NHSN periprosthetic joint infection (based in the Musculoskeletal Infection Society definition) try to have a lower margin of subjectivity when applied. These facts may hinder the comparison of rates over time and between hospitals. Because of these technical difficulties inherent to these indicators and regardless of the importance of the problems which they measure, in some institutions they are being abandoned in favor of other indicators that are easier to apply, for which risk adjustment is easier or not needed and data validation is easier.

In reference to case ascertainment there are also controversial aspects. With day surgery, hospital stays becoming shorter and when health care is done predominantly on an outpatient basis, the search method of the cases has become much more difficult to homogenize, largely because this process is mostly hospital-dependent. Wide variations, depending on whether the providers are public or private, on the geographic location (urban or rural), and also on the organization of health systems in the different countries, have been identified.

The dissemination of results is without any doubt an essential part of surveillance, but there are also aspects which are not known. Is it best to deliver rates of surgical wound infection to the surgeon in private or is it better to give them to all the people involved in that particular healthcare process. The first approach is the classic one and it has proved to be effective. As a counterpart it is well known that several professionals can be involved in surgical site infections and their prevention. If they receive this information, they all have in hand the possibility of incorporating improvements into clinical practice, which ultimately can help to improve the outcome.

The ideal frequency for giving feedback on the rates to professionals is unknown. It would seem that the more frequent the communication of results, the easier it is to introduce corrective measures if a diversion is detected. This approach can be valid for catheter-associated bacteremia in the ICU. However, with surgical site infection the numbers are low and even lower when standardized and reporting results too often can be counter-productive.

In the last two decades there has been a tendency to abandon hospital-wide surveillance and to switch to targeted surveillance. This change has happened because of workload and costs but the efficiency of both systems to prevent HAIs has not been compared in controlled trials. Targeted surveillance is composed of various elements. The most common are the intensive care indicators (catheter-related bacteremia, catheter-related urinary infection and ventilator-associated pneumonia corrected by device days), surveillance of surgical site infections (which often includes several procedures) and surveillance of multi-resistant bacteria infections and Clostridium difficile associated diarrhea.

Some systems have added other indicators such as hospital-wide BSI or process indicators such as hand hygiene compliance, the percentage of central lines correctly inserted or the percentage of correct surgical antibiotic prophylaxis. Hospitals select a mixture of these indicators to design their surveillance programs. Frequently, the selection of indicators can be influenced by the requirements of accreditation agencies or by the mandatory surveillance systems. Currently there is a lack of agreement on which are the best recommended HAI to monitor in each institution. This circumstance does not permit it to be known if some surveillance systems are more efficient than others.

Another aspect of the methodology of surveillance that may be controversial is the fact that currently much of the information needed for monitoring is obtained from electronic medical records. This fact undoubtedly reduces the workload of the ICP and helps with the accuracy of the data but it may influence the effectiveness of the surveillance because it reduces the Hawthorne effect that the visibility of the ICPs working in the wards has.

On the organization of surveillance systems

Regarding the organization of surveillance systems there is a general feeling that a robust national or international protocol to obtain comparable and unbiased data is needed. Perhaps the two most important controversies are whether monitoring should be voluntary or mandatory and whether the results should be kept confidential or made public. Most of the knowledge that we have on the effectiveness and efficiency of surveillance systems to prevent nosocomial infection come from voluntary and confidential systems.

On mandatory versus voluntary surveillance systems:

In the voluntary systems the main advantages are:

  • All the outcome indicators were defined for voluntary reporting systems

  • The efficiency and effectiveness in the prevention of HAIs have been demonstrated

  • The professionals involved in surveillance activities are highly motivated, and interested in the quality improvement. This can be beneficial for the quality of data collection, to accept the need for training and also to better understand the need for performing laborious validation studies to ensure the data consistency.

  • Countries such as USA, England or Germany with experience in voluntary schemes have seen that the degree of participation has increased over the years.

On the contrary, their major disadvantages are:

  • Not all hospitals participate and aggregate rates may not be representative of the territorial rates.

  • Hospitals join and abandon the system or some of its indicators every year. This makes it very difficult to establish benchmarks and also to make interannual comparisons to evaluate trends.

With mandatory surveillance systems, the main advantages are:

  • It is an exercise in transparency and accountability for the institutions also when there is no obligation to disclose the rates.

  • The fact that all the centers must report their data means that aggregate rates of the system are most likely representative of reality in the territory.

  • The fact that all hospitals are required to participate in some indicators, makes inter-annual comparisons and assessment of trends easier.

Moreover, the most important disadvantages are:

  • Some indicators are not sufficiently robust to allow comparisons between hospitals and even less so when comparisons have other implications apart from the main objective of improving HAI prevention. The methodology of some of these outcome indicators of surgical site infection is being evaluated to suit the needs of mandatory surveillance.

  • There is a tendency to replace outcome indicators with process indicators.

  • Hospitals are forced to meet certain surveillance goals that are general for the system and this can lead to a worse prioritization of some HAI prevention efforts in some institutions.

  • Regardless of whether or not results are made public, the fact that they are known at least by the health authorities who are responsible for the system can represent a stimulus not to report. Systems can obtain benefits from not reporting.

On public versus confidential reporting systems:

The last area of controversy regarding the national surveillance systems is whether the results should be kept confidential or whether instead it is better to make them public. Today, it is unknown whether to publish the results is more or less efficient than to maintain them confidential.

The potential advantages of making the results public are:

  • It is an exercise of transparency and accountability that can allow citizens to make better informed decisions. This is only valid as long as the organization of the health system allows them to choose freely.

  • It can permit to insurance companies to hire those who achieve better results and therefore the institutions with better performance will benefit.

  • In countries like England and USA, since the results have been made public, an increased interest in HAI and its prevention has been observed.

The main disadvantages are:

  • A benefit of public reporting on effectiveness of care remains unproven.

  • In the US the lack of agreement between the different states has meant that the results published by each state are different and comparison between them is difficult to do.

  • HAI indicators are of very difficult to interpret and leagues based on results may cause undue economic harm to some institutions.

  • Poor performance on the particular indicators published can determine economic losses and in turn discourage the reporting of HAI or prioritize HAI prevention efforts erroneously.

What national and international guidelines exist related to surveillance systems?

Although JAHCO established the need for surveillance in 1964, the first standardized approach to surveillance was available in 1969. The first specific guidelines on the methodology on nosocomial infection surveillance were published in 1970 by the CDC and they remained unchanged until 1986. Since that time, few specific guidelines on surveillance have been developed but several evidence-based guidelines on HAI prevention have been published and updated, and in most of them, the indication and the methodology of the surveillance for that specific HAI is clearly specified.

In 1991 new guidelines specific for surveillance were published by the CDC. In these document specific instructions with the methodology for hospital-wide, intensive care unit, high-risk nursery and surgical wound infection surveillance are described. The responsibility to select which components each institution should use is not defined and they recommend that hospitals should determine the composition of their own surveillance program.

One of the most important contributions of the document is the precise definition of the denominators for each HAI. The switch from number of admissions in the denominator to patient-days was the first attempt to adjust by exposure to risk. In the case of surgical site infection surveillance, two optional methods were described: the detailed and the limited option. The document already indicates the problems with hospital-wide surveillance and the need to combine different elements of surveillance and not to use a single method. These guidelines already cited problems that remain unresolved even today, such as post discharge methodology and adjustments to risk to permit the comparability of the rates among different hospitals.

A second edition of these guidelines was published in 1998, and advanced in detail on the surveillance methodology techniques. They refer to the need to have a written plan, the necessity for maintaining the intensity of surveillance stable, for maintaining the consistency of the complete surveillance process over the time and the need for periodic evaluation and validation of the data to allow comparisons over time and with other hospitals. The guidelines are subdivided into seven recommended practices: assessing the population, selecting the outcome or process indicators, use of standardized definitions of HAI, characteristics of the data collection process and of the way of performing the rates analysis, the risk adjustment and also the way of feeding back the data obtained. In all cases, practical examples are also described.

In 1999 the Hospital Infection Control Practices Advisory Committee (HICPAC) published the Guideline for Prevention of Surgical Site Infection. It is a comprehensive guideline that includes all the knowledge to that date on the prevention of surgical site infection. An extensive part of the document is dedicated specifically to surveillance of surgical site infection. It describes the usefulness and limitations of the different attempts at risk adjustment and recalls that stratification for risk is indispensable to make comparisons but does not always guarantee the usefulness of these comparisons.

Authors describe the two main methods to identify the patients: direct observation and indirect detection. Even when direct observation is still the most accurate method and considered the gold standard, the indirect method has good sensitivity and specificity when compared with the direct method. The indirect method basically consists of obtaining information through the infection control practitioner from different sources (review of laboratory reports, patient records and discussion with care providers). These guidelines also emphasize the need to perform post-discharge surveillance and the absence of consensus about the best way to do it.

The Society for Healthcare Epidemiology of America (SHEA) the Infectious Diseases Society of America (IDSA) and the Association for Professionals in Infection Control and Epidemiology (APIC) and partner organizations (AHA, JAHCO) jointly published science-based and practical recommendations for acute care hospitals for the prevention of common HAIs. These guidelines that entitled Compendium of Strategies to Prevent Healthcare-Associated Infections in Acute Care Hospital are based on previous HICPAC guidelines but they are a further step to give practical evidence-based recommendations to all the stakeholders participating in HAI prevention. In each HAI not only is the need for surveillance described, but also the strength of the recommendation is classified and the quality of evidence is also informed for each different HAI. In 2016 WHO has published new recommendations on surgical site infection prevention.

In 2005 the HICPAC published the first guidelines on public reporting of the HAI. In them, they recommend using the established surveillance methods when designing and implementing a mandatory HAI reporting system. They recall the need to choose appropriate process and outcome measures. These have to be robust indicators, easy to validate and they have to permit comparisons to be made among hospitals and over time but their interpretation has to be unequivocal. The main process measures that they recommend for mandatory systems are: the percentage of correct central line insertion practices, percentage of appropriate surgical antibiotic prophylaxis, and influenza vaccination compliance. The two outcome measures that they consider best suited to report in a mandatory system are central-line associated bacteremia and risk-adjusted surgical site infection. Indicators such as catheter-related urinary infection are refused because of the lower associated morbidity and ventilation-associated pneumonia because of the difficulty to detect it accurately.

In 2008 the CDC published a new edition of its NHSN definitions of healthcare-associated infections and the criteria to apply the definitions of the infections and in 2013 some other modifications were incorporated in its manual. These definitions have been adopted by most of national and international surveillance systems.

The SHEA and HICPAC have also published a consensus guideline on the metrics to use to monitor the incidence and prevalence of multidrug-resistant organisms. They explain the most appropriate system to measure each MDRO in different situations and they recall the important unresolved difficulties to use these indicators in the mandatory reporting systems. In fact they recommend not using them for public mandatory reporting until we have better validation studies. In summary they consider that most of these methods are mainly useful to measure trends and also to measure the effect of interventions within a hospital but they are not yet suitable to allow inter-hospital comparisons. Indicators such as MRSA or VRE bacteremia incidence are the only ones sufficiently robust to permit comparison among hospitals and have demonstrated success in measuring prevention of MDRO in the United Kingdom.

What other consensus group statements exist and what do key leaders advise?

Most of the documents cited in the previous guidelines paragraph are consensus documents. There are other consensuses that have been historically important in infection control.

In 1991 the CDC published a consensus document on the limitations of the different HAI rates to make inter-hospital comparisons. Most of the systems that we use today to adjust by risk were defined in this consensus statement. They identified the inability to make inter-hospital comparisons with hospital-wide rates. The adjustment of critical area indicators by device-days and stratification by ICU type was introduced and in the case of High Risk Nursery a further stratification by weight was established. In the Surgical Component, the NNIS risk index was consolidated against the adjustment index. The use of the 75th percentile cut point for the duration of the surgery demonstrated a better discriminatory effect than the two hour cut point. The CDC, SHEA, APIC and SIS Consensus on Surgical Wound Infections Surveillance marked a before and after for Surveillance of SSI and its basic principles remain, despite the fact that updates have been published.

In 1998 a Consensus Panel Report on the Requirements for Infrastructure and Essential Activities of Infection Control and Epidemiology in Hospitals was published by SHEA and APIC and received the endorsement of JAHCO, AHA, HIP-CDC, PIDS, IDSA and NFID. In this document a well-designed surveillance program is considered essential to perform all the rest of infection control activities. They summarize the most important surveillance activities in three recommendations:

  • Surveillance of HAI must be performed (category I) and the process should have: standardized case definitions, definition of the population at risk, appropriate methods of measurement, identification of data sources, definition of numerators and denominators, dissemination of the results and selection of specific events to be monitored.

  • Surveillance data must be appropriately analyzed and used to monitor and improve the outcome of the infection control process (category I).

  • Clinical performance and assessment indicators used for external comparative measurement should meet SHEA and APIC criteria (category II).

In 2005, under the sponsorship of WHO, a group of experts from the European Union coming from countries with well-developed national surveillance systems and from other countries without, established the current needs for national and international HAI surveillance systems and they asked for international case definitions, guidelines to correctly perform surveillance and to analyze the data and to translate the results into practice, reference laboratories for antimicrobial susceptibility testing and typing and international specific training on these duties. They emphasized that a consensus of the minimum national standards of infection prevention must be achieved and in this sense WHO recommendations on Surgical Site Infection prevention have been published in 2016, but they limit to update the preventive measures but not to surveillance methodology aspects.

A group of representatives from the different European countries, many of them involved in their country’s national surveillance systems held a consensus conference to analyze the main problems of infection control for the next decade. On surveillance they declared their concern about the possible undesirable effects of mandatory reporting of healthcare-associated infections and also emphasized the importance of the validity and comparability of data, which is essential to harmonize surveillance among countries.


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