Criteria abstracted from The Users' Guide to Medical Literature, from the Health Information Research Unit and Clinical Epidemiology and Biostatistics, McMaster University

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Article Reviewed:

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The role of gown and glove isolation and strict handwashing in the reduction of nosocomial infection in children with solid organ transplantation.

Slota M, Green M, Farley A, Janosky J, Carcillo J.

Crit Care Med. 2001;29(2):405-412. [abstract]

Reviewed by Ada Lin MD, Washington University and St. Louis Children's Hospital, St. Louis MO

Review posted December 22, 2004

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I. What is being studied?:

The study objective:

To compare the effect of protective gown and glove isolation versus strict handwashing on nosocomial infection in pediatric intensive care unit (PICU) patients with solid organ transplantation.

The study design:

Single center (23 bed PICU), prospective, randomized design using a block randomization design based on organ transplanted, age, and initial admission v. readmission

The patients included:

All children admitted to the PICU immediately after solid organ transplantation (liver, heart, lung, intestinal) and on subsequent readmissions.

The patients excluded:

Children with current infection or known exposure to varicella. Also, children receiving kidney transplants were excluded because their average length of stay was less than 48 hours.

The interventions compared:

Protective gown and glove (G&G) versus strict handwashing (SHW). SHW was defined as a 15 second hand wash with a chlorhexidene gluconate product before every patient contact. Staff caring for patients in this group continued to use universal precautions and sterile gloves as required.

Protective G & G was defined as the use of a disposable, nonwoven, polypropylene high-barrier gown and nonsterile latex gloves (or sterile gear if required) for every patient contact by every staff member or visitor. Both interventions were reinforced through staff education and signs.

The outcomes evaluated:

Primary outcome: Nosocomial infection rate during study. Nosocomial infections were defined as:

1. Infections not apparent at time of PICU admission.
2. Bacterial infections occurring after 48 hrs in the PICU or within 48 hours after leaving the PICU
3. Viral or fungal infections occurring after 5 days in the PICU and within 5 days after leaving the PICU.

Secondary outcome: Compliance with experimental protocols by patient contacts

II. Are the results of the study valid?

Primary questions:

1. Was the assignment of patients to treatments randomized?

Yes. A block randomization design was used on admission to the PICU. Blocks of four were designed as follows: a) according to organ groups (heart, liver, lung +/- other organs, intestines +/- other organs; b) according to age (< 1 yr or > 1 yr of age, for heart or liver only); c) by new transplantation v. readmission without retransplantation.

2. Were all patients who entered the trial properly accounted for and attributed at its conclusion?

Was followup complete?

Yes. Ninety-eight patients were enrolled during the 18 months of study. Forty-six were randomized to the G & G group. Eight patients were withdrawn within 48 hours after randomization; six by parents who wanted to touch their children without gloves and two by investigators because the subjects were infected. Fifty-two patients were randomized to the SHW group with no patients withdrawn. Data is available on primary and secondary outcomes on all ninety patients.

Were patients analyzed in the groups to which they were randomized?

Yes. If readmitted to PICU within 2 weeks from transfer date, then subjects were placed in same randomization group as originally assigned. If readmitted after 2 weeks, then they were randomized again. So, the same patient could be in two arms of the study but the data collected from that randomization would be applied to that group. No study subjects with infection were readmitted to the study. No patient truly crossed over, i.e., was assigned to one group but analyzed as being in the other (if, say, strict G & G was not followed).

Secondary questions:

3. Were patients, health workers, and study personnel "blind" to treatment?

No. The patients and health workers were not blinded to the treatment because they were active participants in the treatment. However, a blinded committee reviewed the infection data monthly to confirm infections.

4. Were the groups similar at the start of the trial?

Patients were similar in the two groups in the variables of gender, organ transplanted, Pediatric Risk of Mortality scores, incision intactness, bed-space location, drug therapy and invasive interventions. Length of stay in the PICU during the study was significantly longer in the G & G group (11.1 vs. 7.14 days, p = 0.014) It is not clear why this group had a longer length of stay, but presumably this puts them at higher risk of infection (although data were normalized to infections per patient days).

5. Aside from the experimental intervention, were the groups treated equally?

Probably. The same post transplant protocols were followed for patients in both groups, although other aspects of care, e.g., routine antibiotics, nutrition, mechanical ventilation is not specified as being protocolized. Whether risk factors or aspects of care, the use of antimicrobials, central venous catheters, TPN, etc, did not vary significantly between both groups. (Table 1) However, there was a trend (p=0.09) toward a decrease in the frequency of direct patient physical contact in the G & G group.

III. What were the results?

1. How large was the treatment effect?

Primary outcome: incidence of nosocomial infections in the PICU among transplant patients

Compared to SHW (3.0/100 patient days), gowning and gloving (2.3/100 patient days) showed no significant difference in infection rates. Also, the infection rate in the overall PICU population did not change significantly from the year before the study or compared with the year after the study. Yet the prestudy infection rate among transplanted patients was 4.9 per 100 days which is significantly higher than the 2.1/100 days in the PICU population overall. G & G protective isolation significantly reduced the nosocomial infection rate compared with the prestudy rate; (from 4.9 to 2.3, p=0.0008). SHW also significantly reduced the rate (4.9 to 3.0, p=0.008). This difference in rates was continued in the 6-month period immediately after the study (compared to prestudy, p=0.0004).

To calculate infections per patient, from the data from Table 3, we can determine the following:

1. Risk of infection in SHW group, x: 12% (6/52 patients)
2. Risk with G & G, y: 21% (8/38)
3. Relative Risk, y/x: 1.8
4. Absolute Risk Increase (Risk Difference), y-x: 9%
5. Relative Risk Increase, [(y-x)/x] x 100: 80%
6. Number Needed to Harm (1/y-x): 11

Note then, that when calculated with each patient as the unit of analysis, the G & G group seemed to have a higher risk of nosocomial infection.

Secondary outcome: compliance with assigned intervention

No difference was noted between compliance for G & G compared with SHW. However, compliance with handwashing before the study (22%) was significantly different from that during the study (76%), p=0.0001. Handwashing was considered compliant only if caregivers washed their hands for at least 15 seconds. The numbers of exposures per contacts per hour were totaled by an anonymous data collector during varied 3-hr periods of the day and varied days of the week.

2. How precise was the estimate of the treatment effect?

The 95% confidence intervals of the relative risk increase in the G & G group are 0.7 to 4.8. These are wide intervals, indicating a lack of precision, and since they cross one, we cannot conclude that the apparent increase in risk from G & G is significant.

This study's sample size was calculated to detect the same difference observed in the study done by Klein et al (1). In 1989, they published a single center randomized control trial of 95 patients that showed a 50% reduction in nosocomial infection rate by using protective isolation (gown and gloves) in mechanically ventilated PICU patients. However, this earlier study excluded children with immunodeficiencies including solid organ transplant patients. The study done by Slota et al. does show a 25% reduction in the infection rates in the G & G group compared to the SHW group (2.3 vs. 3.0 per 100 patient days). However, because their calculations were aiming to show a 50% difference, they don't have sufficient power behind their study to make the 25% reduction statistically significant.

If this study was repeated in a larger population, the confidence interval would likely narrow and the results might be more reliable or statistically significant. Indeed, the authors themselves suggest that the next step would be a multicenter trial.

IV. Will the results help me in caring for my patients?

1. Can the results be applied to my patient care?

Yes. The patients included in this study were similar in age, gender, co-morbidities and therapeutic interventions as transplant patients in other PICUs.

2. Were all clinically important outcomes considered?

Yes. Incidence of infection and compliance with intervention are both clinically important outcomes. In addition, the authors also looked at the types of nosocomial infections in each treatment group, noting that infectious agents most likely to be prevented by barrier precautions (e.g. rotavirus, coagulase negative staphylococcus, RSV) occurred only in the SHW group.

3. Are the likely treatment benefits worth the potential harms and costs?

Since no difference was shown between the gown and glove group and strict handwashing, there are no treatment benefits to consider. However, since strict handwashing alone was shown to significantly reduce the infection rate, and compliance increased from 22% prestudy to 76% during the study, one might consider that the expense of enforcing strict handwashing via signs and family education could be cheaper than the cost of antimicrobial agents and a prolonged hospitalization by several hundred dollars per patient day.

References:

1. Klein BS, Perloff WH, Maki DG: Reduction of nosocomial infection during pediatric intensive care by protective isolation. N Engl J Med 1989; 320:1714-1721. [abstract]

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