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Citation:
Aiello AE, Coulborn RM, Perez V, Larson EL. Effect of hand hygiene on infectious disease risk in the community setting: a meta-analysis. Am J Public Health. 2008 Aug;98(8):1372-81. Epub 2008 Jun 12.
PubMed ID: 18556606
Study Design:
Meta-Analysis
Class:
M - Click here for explanation of classification scheme.
Research Design and Implementation Rating:
 POSITIVE: See Research Design and Implementation Criteria Checklist below.
Research Purpose:
- To quantify the effect of hand-hygiene interventions on rates of gastrointestinal and respiratory illnesses
- To identify specific interventions with the most potential for reducing symptoms of gastrointestinal and respiratory illnesses
Inclusion Criteria:
- Hand hygiene trials published from January 1960 to May 2007
- Published in any language
- Outcome of a reported or diagnosed gastrointestinal illness (such as shigellosis), a reported or diagnosed respiratory illness (such as influenza), a combination of general gastrointestinal or respiratory symptoms of infection (such as diarrhea or runny nose), or gastrointestinal or respiratory infectious symptom-related absences (such as school absence for a "cold")
- Independent variable was a hand-hygiene intervention, such as hand-hygiene education, soap-use intervention (nonantibacterial or antibacterial soap), or waterless hand sanitizer
- Articles were restricted to intervention trials conducted in the community and employing a randomized or quasi-experimental study design
Exclusion Criteria:
- Hand-hygiene interventions that were implemented as part of a major public health infrastructure or systems improvement project, such as municipal water supply and waste disposal
- Setting was healthcare facility or specialized setting, such as military
- Articles that did not provide an effect estimate such as a rate ratio, odds ratio, etc.
- Articles that did not provide enough data to allow calculation of a rate ratio
Description of Study Protocol:
Recruitment
Articles were identified from the search of four electronic databases: PubMed (1960 - 2007), Scopus for EMBASE (1974 - 1980), Science Citation Index (Web of Science; 1960 - 2007), and Cochrane Library (1988 - 2007), using 241 keyword combinations. Reference lists were also searched for additional related articles, and a manual search was performed with the author's reference database.
Design: Meta-Analysis
Blinding used (if applicable): not applicable
Intervention (if applicable):
Two authors independently evaluated selected studies.
Statistical Analysis
- Publication bias was assessed graphically with funnel plots, the Begg and Mazumdar rank correlation and the Egger test
- Meta-analyses conducted using random effects models
- Forest plots were generated with a mixed-modeling procedure
- To assess statistical heterogeneity, Cochran Q-statistic and the I2 statistic were calculate for each pooled estimate
- To assess potential sources of heterogeneity, multilevel random effects models were used
- To calculate the preventive fraction for exposure, the rate ratios and corresponding confidence intervals were used
 Data Collection Summary:
Timing of Measurements
Not applicable.
Dependent Variables
- Gastrointestinal and respiratory infectious illnesses: reported or diagnosed gastrointestinal illness (such as shigellosis), a reported or diagnosed respiratory illness (such as influenza), a combination of general gastrointestinal or respiratory symptoms of infection (such as diarrhea or runny nose), or gastrointestinal or respiratory infectious symptom-related absences (such as school absence for a "cold"), grouped by specific outcome into three possible categories
Independent Variables
- Hand hygiene interventions: hand-hygiene education, soap-use intervention (nonantibacterial or antibacterial soap), or waterless hand sanitizer, grouped by specific intervention into seven possible categories
Control Variables
Description of Actual Data Sample:
Initial N: 5,378 articles in initial keyword search. 718 were initially reviewed by abstract or full article. 602 studies were retrieved for detailed assessment.
Attrition (final N): 30 studies included in the meta-analysis. 572 articles were excluded on basis of review criteria.
Age: not applicable
Ethnicity: not applicable
Other relevant demographics:
Anthropometrics
Location: International studies
Summary of Results:
Key Findings:
- Improvements in hand hygiene resulted in reductions in gastrointestinal illness of 31% (overall RR = 0.69, 95% confidence interval: 0.58, 0.81) and reductions in respiratory illness of 21% (overall RR = 0.79, 95% confidence interval: 0.66, 0.95).
- The most beneficial intervention was hand-hygiene education with use of nonantibacterial soap (RR = 0.61, 95% confidence interval: 0.43, 0.88).
- Hand-hygiene education showed a strong protective effect against gastrointestinal illnesses (RR = 0.69, 95% confidence interval: 0.50, 0.95).
- The pooled RR for the use of alcohol-based hand sanitizer with hand-hygiene education showed a significant reduction in combined illnesses (RR = 0.79, 95% confidence interval: 0.67, 0.93).
- The pooled RR for the use of alcohol-based hand sanitizer alone showed a significant reduction in combined illness outcomes, as did the pooled RR for using benzalkonium chloride-based hand sanitizer.
- Use of antibacterial soap showed little added benefit compared with use of nonantibacterial soap.
Rate Ratios and 95% Confidence Intervals for the Association Between Specific Hand-Hygiene Interventions and Each Illness Outcome
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Interventions
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Gastrointestinal Illness (n = 24)
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Respiratory Illness (n = 16)
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Combined Illnesses (n = 10)
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Education vs control
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0.69 (0.50, 0.95) |
0.86 (0.73, 1.00) |
---
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| Nonantibacterial soap with education vs control |
0.61 (0.43, 0.88) |
0.49 (0.40, 0.61) |
0.94 (0.74, 1.18) |
| Antibacterial soap with education vs control |
0.59 (0.33, 1.06) |
0.50 (0.40, 0.61) |
--- |
| Antibacterial soap vs nonantibacterial soap |
0.99 (0.54, 1.83) |
1.00 (0.84, 1.19) |
0.96 (0.71, 1.30) |
| Alcohol-based hand sanitizer vs control |
--- |
--- |
0.74 (0.59, 0.93) |
| Alcohol-based hand sanitizer with education vs control |
0.77 (0.52, 1.13) |
0.93 (0.84, 1.03) |
0.79 (0.67, 0.93) |
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Benzalkonium chloride-based hand sanitizer vs control
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0.58 (0.30, 1.12)
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0.60 (0.45, 0.81)
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0.59 (0.45, 0.78)
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Other Findings
- A greater proportion of hand-hygiene intervention studies were conducted in developed than in lesser developed countries
- Sources of heterogeneity were not statistically significant for either gastrointestinal or respiratory outcomes
Author Conclusion:
The results of our meta-analyses provide the needed data synthesis for formulating consistent community-based hand-hygiene guidelines. First, we confirmed that hand-hygiene interventions are efficacious for preventing gastrointestinal illnesses, in both developed and lesser-developed countries. However, the overall impact of hand hygiene was less efficacious for respiratory illnesses. Overall, there was little evidence for an additional impact of new products, such as alcohol-based hand sanitizers or antibacterial soaps compared with nonantibacterial soaps, for reducing either gastrointestinal or respiratory infectious illness symptoms. Last, there is a need to include microbiological assessments of the agents that may be associated with clinical symptoms of infection so that agent-specific targeted hand-hygiene practices can be evaluated.
Reviewer Comments:
Authors note that very few studies in the review rigorously assessed hand-hygiene practices during the intervention period or monitored the use of products. Authors note the following limitations:
- In some cases, classification of the intervention was unclear due to multiple components
- For some interventions, only single studies were available, so pooled estimates could not be generated
- Heterogeneity was significant in pooled estimates across all studies
- Evidence of publication bias for gastrointestinal illness outcomes, therefore, the pooled estimated generated may be exaggerated for this outcome
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Research Design and Implementation Criteria Checklist: Review Articles
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Relevance Questions
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1.
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Will the answer if true, have a direct bearing on the health of patients? |
Yes
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2.
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Is the outcome or topic something that patients/clients/population groups would care about? |
Yes
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3.
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Is the problem addressed in the review one that is relevant to nutrition or dietetics practice? |
Yes
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4.
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Will the information, if true, require a change in practice? |
Yes
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Validity Questions
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1.
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Was the question for the review clearly focused and appropriate? |
Yes
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2.
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Was the search strategy used to locate relevant studies comprehensive? Were the databases searched and the search termsused described? |
Yes
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3.
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Were explicit methods used to select studies to include in the review? Were inclusion/exclusion criteria specified and appropriate? Were selection methods unbiased? |
Yes
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4.
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Was there an appraisal of the quality and validity of studies included in the review? Were appraisal methods specified, appropriate, and reproducible? |
Yes
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5.
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Were specific treatments/interventions/exposures described? Were treatments similar enough to be combined? |
???
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6.
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Was the outcome of interest clearly indicated? Were other potential harms and benefits considered? |
Yes
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7.
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Were processes for data abstraction, synthesis, and analysis described? Were they applied consistently across studies and groups? Was there appropriate use of qualitative and/or quantitative synthesis? Was variation in findings among studies analyzed? Were heterogeneity issued considered? If data from studies were aggregated for meta-analysis, was the procedure described? |
Yes
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8.
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Are the results clearly presented in narrative and/or quantitative terms? If summary statistics are used, are levels of significance and/or confidence intervals included? |
Yes
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9.
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Are conclusions supported by results with biases and limitations taken into consideration? Are limitations of the review identified and discussed? |
Yes
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10.
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Was bias due to the review’s funding or sponsorship unlikely? |
Yes
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Copyright American Dietetic Association (ADA).
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