Personal protective equipment for preventing highly infectious diseases due to exposure to contaminated body fluids in healthcare staff Edited (no change to conclusions), comment added to review

Abstract

Abstract Background

In epidemics of highly infectious diseases, such as Ebola Virus Disease (EVD) or Severe Acute Respiratory Syndrome (SARS), healthcare workers (HCW) are at much greater risk of infection than the general population, due to their contact with patients' contaminated body fluids. Contact precautions by means of personal protective equipment (PPE) can reduce the risk. It is unclear which type of PPE protects best, what is the best way to remove PPE, and how to make sure HCW use PPE as instructed.

Objectives

To evaluate which type of full body PPE and which method of donning or doffing PPE have the least risk of self‐contamination or infection for HCW, and which training methods increase compliance with PPE protocols.

Search methods

We searched MEDLINE (PubMed up to 15 July 2018), Cochrane Central Register of Trials (CENTRAL up to 18 June 2019), Scopus (Scopus 18 June 2019), CINAHL (EBSCOhost 31 July 2018), and OSH‐Update (up to 31 December 2018). We also screened reference lists of included trials and relevant reviews, and contacted NGOs and manufacturers of PPE.

Selection criteria

We included all controlled studies that compared the effects of PPE used by HCW exposed to highly infectious diseases with serious consequences, such as Ebola or SARS, on the risk of infection, contamination, or noncompliance with protocols. This included studies that used simulated contamination with fluorescent markers or a non‐pathogenic virus.

We also included studies that compared the effect of various ways of donning or doffing PPE, and the effects of training in PPE use on the same outcomes.

Data collection and analysis

Two authors independently selected studies, extracted data and assessed risk of bias in included trials. We planned to perform meta‐analyses but did not find sufficiently similar studies to combine their results.

Main results

We included 17 studies with 1950 participants evaluating 21 interventions. Ten studies are Randomised Controlled Trials (RCTs), one is a quasi RCT and six have a non‐randomised controlled design. Two studies are awaiting assessment.

Ten studies compared types of PPE but only six of these reported sufficient data. Six studies compared different types of donning and doffing and three studies evaluated different types of training. Fifteen studies used simulated exposure with fluorescent markers or harmless viruses. In simulation studies, contamination rates varied from 10% to 100% of participants for all types of PPE. In one study HCW were exposed to Ebola and in another to SARS.

Evidence for all outcomes is based on single studies and is very low quality.

Different types of PPE

PPE made of more breathable material may not lead to more contamination spots on the trunk (Mean Difference (MD) 1.60 (95% Confidence Interval (CI) −0.15 to 3.35) than more water repellent material but may have greater user satisfaction (MD −0.46; 95% CI −0.84 to −0.08, scale of 1 to 5).

Gowns may protect better against contamination than aprons (MD large patches −1.36 95% CI −1.78 to −0.94).

The use of a powered air‐purifying respirator may protect better than a simple ensemble of PPE without such respirator (Relative Risk (RR) 0.27; 95% CI 0.17 to 0.43).

Five different PPE ensembles (such as gown vs. coverall, boots with or without covers, hood vs. cap, length and number of gloves) were evaluated in one study, but there were no event data available for compared groups.

Alterations to PPE design may lead to less contamination such as added tabs to grab masks (RR 0.33; 95% CI 0.14 to 0.80) or gloves (RR 0.22 95% CI 0.15 to 0.31), a sealed gown and glove combination (RR 0.27; 95% CI 0.09 to 0.78), or a better fitting gown around the neck, wrists and hands (RR 0.08; 95% CI 0.01 to 0.55) compared to standard PPE.

Different methods of donning and doffing procedures

Double gloving may lead to less contamination compared to single gloving (RR 0.36; 95% CI 0.16 to 0.78).

Following CDC recommendations for doffing may lead to less contamination compared to no guidance (MD small patches −5.44; 95% CI −7.43 to −3.45).

Alcohol‐based hand rub used during the doffing process may not lead to less contamination than the use of a hypochlorite based solution (MD 4.00; 95% CI 0.47 to 34.24).

Additional spoken instruction may lead to fewer errors in doffing (MD −0.9, 95% CI −1.4 to −0.4).

Different types of training

The use of additional computer simulation may lead to fewer errors in doffing (MD −1.2, 95% CI −1.6 to −0.7).

A video lecture on donning PPE may lead to better skills scores (MD 30.70; 95% CI 20.14,41.26) than a traditional lecture.

Face to face instruction may reduce noncompliance with doffing guidance more (OR 0.45; 95% CI 0.21 to 0.98) than providing folders or videos only.

There were no studies on effects of training in the long term or on resource use.

The quality of the evidence is very low for all comparisons because of high risk of bias in all studies, indirectness of evidence, and small numbers of participants.

Authors' conclusions

We found very low quality evidence that more breathable types of PPE may not lead to more contamination, but may have greater user satisfaction. Alterations to PPE, such as tabs to grab may decrease contamination. Double gloving, following CDC doffing guidance, and spoken instructions during doffing may reduce contamination and increase compliance. Face‐to‐face training in PPE use may reduce errors more than video or folder based training. Because data come from single small studies with high risk of bias, we are uncertain about the estimates of effects.

We still need randomised controlled trials to find out which training works best in the long term. We need better simulation studies conducted with several dozen participants to find out which PPE protects best, and what is the safest way to remove PPE. Consensus on the best way to conduct simulation of exposure and assessment of outcome is urgently needed. HCW exposed to highly infectious diseases should have their use of PPE registered and should be prospectively followed for their risk of infection in the field.

Author(s)

Jos H Verbeek, Blair Rajamaki, Sharea Ijaz, Christina Tikka, Jani H Ruotsalainen, Michael B Edmond, Riitta Sauni, F Selcen Kilinc Balci

Abstract

Plain language summary

Clothes and equipment for healthcare staff to prevent Ebola and other highly infective diseases

Healthcare staff are at risk of infections such as Ebola Virus Disease and SARS. One way of preventing infection is to use personal protective equipment, such as protective clothing, gloves, masks, and goggles to prevent contamination of the worker. It is unclear which type of equipment protects best and how it can best be removed after use. It is also unclear what is the best way to train workers to comply with guidance for this equipment.

Studies found

We found 17 studies with 1950 participants that evaluated 21 interventions. We divided the studies into three categories: comparing types of protective clothing, comparing ways to put it on and take it off, and different ways to train the healthcare workers in the use of the protective clothing. Twelve of the studies used a fluorescent marker or a harmless virus to simulate what happens in hospitals. Two studies were conducted under field circumstances: one during the SARS epidemic in 2003 and one during the Ebola epidemic in 2015. Three studies with 962 participants compared the effect of active training on the use of protective equipment to passive training. All studies had either an unclear or a high risk of bias.

Various types of clothing compared

In spite of protective clothing, the fluorescent marker was found on 10% to 100% of workers. In one study, more breathable clothing did not lead to more contamination than non‐breathable clothing, but users were more satisfied. Gowns led to less contamination than aprons in another study. Four studies evaluated changes to the protective clothing to make it easier to take it off. Gowns with gloves attached at the cuff that were taken off together also led to less contamination than the gown and gloves taken off separately. Studies that modified the gloves and face masks with tabs to grip when removing the protective clothing led to less contamination. Four studies did not report enough data to enable conclusions. This evidence is very low quality.

Various types of removal of clothing compared

In one study, two pairs of gloves led to less contamination than only one pair of gloves. In another study that used two pairs of gloves, using an alcohol‐based hand sanitizer for cleaning the inner gloves did not lead to less contamination than hypochlorite solution. In another study, following CDC guidance for apron or gown removal led to less contamination. One study found that those who were given spoken instructions on how to properly take off the contaminated protective clothing were less contaminated compared to those who did not have the spoken instruction. One study did not report enough data to enable conclusions. This evidence is also very low quality.

Active training

Active training, including computer simulation led to less errors with guidance on which protection to use and how to remove it among healthcare staff compared to passive training. In one study, participants who watched a video, compared to a traditional lecture on how to correctly put on the protective clothing had better scores when tested on how to put on the protective clothing.

Quality of the evidence

We judged the quality of the evidence to be very low because of limitations in the studies, indirectness, and small number of participants.

What do we still need to find out?

There were no studies on the effects of goggles or face shields. Researchers need to agree on the best way to simulate exposure. Then, more simulation studies are needed with at least 60 participants, preferably using exposure to a harmless virus, to find out which type and combination is most protective. The best way to remove protective clothing after use is also unclear. We also need studies to find out which training works best in the long‐term. Healthcare staff exposed to highly infectious diseases should have their protective equipment registered and be followed for their risk of infection. We urge NGOs to organise more studies and register and record the type of PPE used by their workers.

Author(s)

Jos H Verbeek, Blair Rajamaki, Sharea Ijaz, Christina Tikka, Jani H Ruotsalainen, Michael B Edmond, Riitta Sauni, F Selcen Kilinc Balci

Reviewer's Conclusions

Authors' conclusions

Implications for practice

In addition to other infection control measures, consistent use of full body PPE can diminish the risk of infection for HCW. EN and ISO standards for chemical protective clothing and fabric permeability for viruses are helpful to determine which PPE should technically protect sufficiently against highly infectious diseases. However the risk of contamination depends on more than just these technical factors. In simulation studies, contamination happened in almost all intervention and control arms.

There is very low quality evidence, based on single exposure simulation studies, that more breathable fabric may still lead to similar levels of contamination protection as less breathable fabric, and may be preferred by users. The lack of using currently accepted standards in the included studies prevents the extrapolation of results of studies comparing PPE types to PPE in current use. Changes to PPE such as adding tabs to gloves or masks or closer fit at the neck or the wrist may facilitate doffing without contamination.

For different procedures of donning and doffing, there is very low quality evidence based on a single study each that double gloves, as part of PPE and following CDC guidelines, may reduce the risk of contamination. The protection obtained from use of alcohol‐based hand rub during doffing did not differ from the protection obtained by using chlorine‐based disinfection.

For various training procedures there is very low quality evidence that more active training (including video or computer simulation or spoken instructions) may increase compliance with instructions compared to passive training (lectures or no added instructions). There are no studies that have compared methods to retain PPE skills needed for proper donning and doffing in the long term.

The quality of the evidence is very low for all comparisons because conclusions are based on single studies and a high or unclear risk of bias in studies, indirectness of evidence, and small numbers of participants. This means that we are uncertain about the estimates of effects, and it is therefore likely that the true effects may be substantially different from the ones reported in this review.

Implications for research

We concur with WHO that there is a need to carry out a re‐evaluation of how PPE is standardised, designed and tested (WHO 2018). What is missing is a harmonized set of PPE standards and a unified design for PPE to be used when taking care of patients with highly infectious diseases.

We call on NGOs in medical relief work to organise studies and to raise awareness about the lack of evidence for the effect of specific PPE. We also call upon them to develop a more transparent and uniform labeling of infection control measures and the protection level of PPE for HCW. We believe that this is an important prerequisite for the universal implementation of infection control measures for HCW.

Simulation studies are a feasible and relatively simple way to compare different types of PPE and to find out which protects best against contamination. It is a prerequisite for a reliable answer that methods of simulation studies are standardised in terms of exposure and outcome measurement. Viral marker Bacteriophage MS2 seems to be the most sensitive marker and we would advocate to use this. Studies should have sufficient power. To be able to detect a relatively large RR of 0.5 with a large control group rate of contamination of 0.7, assuming α = 0.05 and β = 0.80, a sample size of 62 would be needed.

To find out how PPE behaves under real exposure, we need prospective follow‐up of HCW involved in the treatment of patients with highly infectious diseases, with careful registration of PPE and risk of infection. Because different NGOs use different PPE guidance, cohorts of workers would be relatively simple to establish if there would be sufficient political will. Here, the effect sizes would be smaller and thus the sample size should be bigger than 60.

In addition, case‐control studies comparing PPE use among infected HCW and matched healthy controls, using rigorous collection of exposure data, can provide information about the effects of PPE on the risk of infection. The sample sizes should be much bigger than the current case studies because we would like to detect small but important differences in effect between various combinations of PPE such as gowns versus coveralls. There is a need for collaboration between organisations serving epidemic areas to carry out this important research in circumstances with limited resources, and during the throes of an outbreak.

We also need more randomised controlled studies of the effects of one type of training versus another, to find out which training works best, especially at long‐term follow‐up of one year or more. Also here, the effect size seems to be quite large and thus a sample size of around 60 seems to provide adequate power.

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