Impact of hand hygiene on healthcare associated infections:

Four key studies

Josh FreemanDepartment of Clinical Microbiology

ADHB

• Before-after intervention study (Quasi-experimental)– “Before” - 1994– “After” - 1995-1998

• Large teaching hospital (University of Geneva Hospitals)• Standardisation of outcome measures

– auditing of hand hygiene compliance (5 moments)– nosocomial infections (NNISS definitions) measured by annual

prevalence surveys– MRSA attack rate – new hospital acquired cases per 100

admissions

HH compliance

HH compliance improved overall from 47.6% at baseline in 1994 to 66.2% in December 1997 (p<0.001)

Impact on nosocomial infections and MRSA attack rate

Between 1994 and 1998, MRSA infections decreased from 2.16 /10000 PD to 0.93 / 10000 PD (p<0.001)

MRSA bacteraemia decreased from 0.74 to 0.24 / 10000 PD (p<0.001)

Evidence that HH affects healthcare-associated infections: Strengths and Weaknesses

Strengths• Large hospital with large

sample size• Temporal associaton

between improved hand hygiene practice and reduced nosocomial infections and MRSA attack rate

• Extended time frame post intervention

Weaknesses• Other interventions targeting

MRSA carried out simultaneously

• Few data points for nosocomial infection rates (particularly pre-intervention)

• “Nosocomial infections” may be subject to classification bias despite standardised definitions

• Before-after intervention study – Before: Jan 1999-May 2001– After: May 2001- April 2004

• Five wards at Austin Health, Melbourne• Intervention

– HH programme – Mupirocin / triclosan for MRSA colonised patients on admission

• Outcomes – Standardised HH compliance auditing (“5 moments”)– Standardised definitions

• MRSA bacteraemia• MRSA clinical isolates• ESBL-E. coli and K. pneumoniae clinical isolates

HH compliance pre and post intervention

Overall – 21% pre-intervention to 42% post intervention

MRSA rates pre and post intervention

Slope<0; p<0.001

Slope<0;p=0.003

ESBL rates pre and post intervention

Evidence that HH affects healthcare-associated infections: Strengths and Weaknesses

Strengths• Substantial and significant

association between program onset, improved HH compliance and improved trends in MRSA bacteraemia; MRSA clinical isolates; and ESBL clinical isolates

• Large number of data points pre and post intervention

Weaknesses• Intervention included

decolonisation for MRSA, therefore difficult to estimate relative impact of HH on MRSA rates

• Before-after study (Quasi-experimental study)– Standardised process and outcome measures

• auditing of HH compliance 4 monthly (5 moments)• Standardised definitions of MRSA bacteraemia / clinical isolates

• Pilot study– 6 Victorian healthcare institutions over 24 month period

• Statewide study – 75 Victorian hospitals over 12 month period– Rolled out in two stages: Stage 1 – March 2006-April 2007 and stage 2

July 2006-June 2007

HH Compliance: Pilot program

MRSA bacteraemia rates: Pilot program

MRSA clinical isolates: Pilot program

HH compliance: Statewide rollout

MRSA bacteraemia rates: Statewide rollout

MRSA clinical isolates: Statewide rollout

Evidence that HH affects healthcare-associated infections: Strengths and Weaknesses

Strengths• Large, multicentre study• Improved HH practice temporally

associated with significant reductions in MRSA bacteraemia in both the pilot and statewide studies

• Large number of data points before and after the intervention

• MRSA bacteraemia–less vulnerable to classification bias than many endpoints (“hard” endpoint)

Weaknesses• Quasi-experimental, non-

randomised study with historical controls– therefore intrinsically vulnerable to confounding

• Concurrent MRSA-specific measures not documented

• MRSA clinical isolates started to decrease prior to commencing the program (raising possibility that factors other than the HH program may have been driving change)

24 month Outcomes from the Australian National Hand Hygiene Initiative (MJA -in press)

• National HH initiative (Hand Hygiene Australia)• Quasi-experimental study (2009-2010)

– “Before” - Jan 2007-Dec 2008– “After” - Jan 2009-Dec 2010

• Nationally standardised – Auditing of HH compliance (“5 moments”)– MRSA bacteraemia– Hospital-onset SA/MRSA bacteraemia

HH compliance by state: 2009-2010 (post intervention)

Overall 43.6% at baseline to 67.8% post intervention

National MRSA bacteraemia rates pre and post intervention

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Apr-07 Nov-07 Jun-08 Dec-08 Jul-09 Jan-10 Aug-10 Feb-11

Rate

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MRS

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Pre NHHI

Post NHHI Implementation

Slope<0;p=0.008

Hospital-onset S. aureus bacteraemia rates post intervention

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MRSA /10,000

MSSA/10,000

SAB/10,000

Linear (MRSA /10,000)

Linear (MSSA/10,000)

Linear (SAB/10,000)

Evidence that HH affects healthcare-associated infections: Strengths and Weaknesses

Strengths• First nationwide before-after

intervention study for HH programme with outcome data

• Large multi centre study• Utilises a “hard” endpoint

(MRSA bacteraemia)• Strong temporal association

with improved compliance and reduced MRSA bacteraemia

• Large number of data points pre and post intervention

Weaknesses• Vulnerable to confounding

(like all quasi-experimental studies)

• No reduction in “hospital-onset” S. aureus bacteraemia or “hospital-onset” MRSA bacteraemia

HH compliance infection: Association versus causality

Bradford Hill Criterion Supports improved HH compliance as a means to reduce infection?

Association is strong? YES – Statistically significant association between HH and infection rates

Association is seen consistently? YES – Consistent association in four well designed studies

Cause precedes effect? YES – Improvements in hand hygiene have preceded / coincided with reduced infections

Biological gradient (dose-response between cause and effect)?

YES - Inverse correlation between HH compliance rates and rates of infection

Biologically plausible? YES – Hands of healthcare workers known to be frequently contaminated with potential pathogens including MRSA

Coherence (compatible with existing knowledge)?

YES- A causal relationship would be consistent with accepted models of pathogenesis of healthcare-associated infections

Subject to experiment? NO – experimental studies not feasible / ethical

Alternate explanations for association?

YES – Difficult to rationalise temporal association between HH compliance and infectious endpoints based on alternative explanations