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					EXAMPLES OF SUMMARY TABLE: Ribner et al 1986
Study: Ribner et al 1986                 Design: Prospective cross-over cohort study (with predefined
Setting: SICU and SIMU                   Location: Texas, USA               Dates: Not specified
Population characteristics: Both units based in a 720-bed tertiary hospital with endemic MRSA and ICT.
SICU: 32 beds, 3181 patient days during study.
SIMU: 20 beds, 2205 patient days
Stated aim of study: To assess whether using modified infection control precautions appropriate to
patients’ sites of colonisation or infection with MRSA results in the same degree of transmission as placing
all patients, colonised or infected, in strict isolation
Major infection control changes during the study: Patient isolation

                           Isolation                                             Screening         Eradication   Other
SICU                       Modified precautions Masks and gloves unless:         All patients      None
Phase 1                    • Colonised or infected wounds: masks, gloves,        screened          described
2 months                   gowns and single rooms preferred                      weekly and
                           • Colonisation or infection of LRT or burns: strict   after discharge
Phase 2                    Strict isolation                              As phase 1        None
2 months (starting         (Masks, gloves, gowns, single rooms preferred)                  described
straight after phase 1)
SIMU                       Strict isolation                              All patients      None
Phase 3                                                                  screened          described
2 months (at same time                                                   weekly and
as Phase 1 in SICU)                                                      after discharge
2 months (starting         Modified precautions                          As phase 1        None
straight after phase 1)                                                                    described
Isolation details: 8 (25%) SICU beds in single rooms. All 20 SIMU beds as single rooms
Screening details: Screening sites: nose, wounds, lesions, tracheostomy sites, sputum, abnormal skin
Eradication details: No eradication described
Reported outcomes:
1. Incidence:
                                            Modified isolation (phases 1       Strict isolation (phases 2 and
                                            and 4)                             3)
Total MRSA acquisitions in SIMU                                  2                                    7
Total MRSA acquisitions in SICU                                  7                                    4
MRSA colonisations acquired                                      4                                    5
MRSA bacteraemias (SICU and                                      1                                    2
Patient days in SICU                                          1535                                 1646
Patient days in SIMU                                          1145                                 1060
Definitions: Infection criteria: none specified
MRSA carriage on admission: positive swabs taken within 72 h of admission
2. Point prevalence: No data
3. Trends: No data
Economic evaluation: Estimated cost per patient day: strict isolation US$40–50; modified precautions: $5.
Estimated annual savings: $43,800. Details of calculations not supplied
MRSA strain details: None given
Analysis in paper: No appropriate analysis ( Chi-square and Fisher’s exact test used)
Major confounders and bias: Effects of earlier phases may have contaminated later phases. Study is
also vulnerable to the existence of underlying trends (since settings were chosen in part for the high MRSA
levels, a decreasing trend due to regression to the mean effects is plausible over the short time intervals
considered). Together these have the potential to mask effects due to the control policy.
What the authors conclude: Modified precautions can be as effective as strict isolation in preventing
MRSA transmission in hospitals
Assessment of authors’ conclusions: The study does not provide any evidence that modified
precautions are less effective than strict isolation, although the power to detect a difference is not reported
and is likely to be very low. Between phase ‘contamination’ could be important, and conclusions are
vulnerable to the existence of underlying trends
EXAMPLES OF SUMMARY TABLE: Harbarth 2000 and Pittet 2000
Pittet D, Hugonnet S, Harbarth S, Mourouga P, Sauvan V, Touveneau S, et al. Effectiveness of a hospital-wide
programme to improve compliance with hand hygiene. Lancet 2000;356:1307–12.
Harbarth S, Martin Y, Rohner P, Henry N, Auckenthaler R, Pittet D. Effect of delayed infection control measures on a
hospital outbreak of methicillin-resistant staphylococcus aureus. J Hosp Infect 2000;46:43–9.

Study: Harbath 2000 & Pittet 2000            Design: Hybrid retrospective (before 1994) and prospective (after 1994) interrupted
                                             time series.
Setting: 1300-1600 bed teaching              Location: Geneva, Switzerland               Dates: 1989-1997
Population characteristics: Number of beds: 1600 in early 1990s; 1400 in mid-1990s; 1300 in late 1990s*. MRSA initially
epidemic, later became endemic. ICT with 5 full time infection control nurses from Oct 1992. Number of patients during study:
506012. Mean age of MRSA patients (SD): 68 (23) years.
Stated aim of study: 1. To evaluate consequences of delayed outbreak containment during a four-year absence of control. 2.To
describe the effect of a hand hygiene programme on compliance and hospital acquired infection.
Major infection control changes during the study: Carer hand-hygiene education and feedback; patient isolation; screening;
MRSA eradication; antibiotic use; automatic readmission alerts, disinfection, sterilization, air control & building construction.
               Isolation                     Screening                               Eradication                Other measures
Phase 1        None                          None                                None                    No MRSA control
48 months                                                                                                measures
(Jan 1989
- Dec
Phase 2       1.Single room.                 1.Admission screens for previous    Mupirocin and           1.CDC guidelines 1983
24 months     2. Cohorting on closed and     MRSA patients.                      chlorhexidine.          2.Computer alerts for
(Jan 1993     open bays in special           2.Contacts screened.                Mupirocin used for      readmitted MRSA
- Dec         circumstance (e.g. unit        3.Treated MRSA patients: weekly     almost all patients,    patients (July 1994 on).
1994)         specific outbreaks).           for 4 weeks, then monthly.          irrespective of
                                                                                 MRSA carriage*.
Phase 3         As phase 2                       As phase 2                      As phase 2 until            As phase 2 +
36 months                                                                        September 1997.             staff hand-hygiene
(Jan 1995                                                                                                    education & feedback
- Dec                                                                                                        programme
Isolation details: From 1993 single rooms may not have been used when there was nasal carriage only and lack of available
rooms. ). Contact for overflow with nasal carriage only. 60 single rooms available for acute services patients (without negative
Screening details. Screening sites: nose, lesion, groin, infected sites. Patients in "septic" orthopaedic ward screened on
admission from July 1994.
Eradication Details: From phase 2 most patients received 1 nasal mupirocin courses, irrespective of MRSA carriage*. After
September 1997 mupirocin was limited to those with known nasal carriage and without chronic skin lesions and indwelling devices.
Criteria for eradication: 2 negative sets of cultures 24 hrs apart.
Harbath 2000 & Pittet 2000 (continued)
Reported outcomes:
1. Incidence:
Total MRSA: 1771 new MRSA cases from 506,012 admitted patients over whole study. Annual number of newly identified MRSA
patients per 100 admissions reported over whole study (‘attack rate’). Annual number of MRSA patients per 100 admission (i.e.
including previously identified patients) reported over whole study (‘prevalence’). New cases per 1000 patient days reported
Infections: Annual incidence of bacteraemias reported over whole study (1989–97). Total MRSA infections per 10,000 patient
days: 2.16 in 1994; 0.93 in 1998
Colonisation: No data
Carriage on admission: Initial colonisation status of readmitted known MRSA-positive patients recorded July 1994–June 1995.
114 of 347 (32.9%) were MRSA positive
Attributable deaths: No data
Denominators (in addition to those above): Number of screening cultures.
Note: only one isolate per patient per year was included in all the laboratory-based surveillance results
Definitions: Infection : CDC criteria. MRSA in urine cultures considered infections only if antibiotics given.
Carriage on admission: reported positive swabs ≤ 72 h post-admission, unless indications to the contrary
2. Point prevalence:
No data on point prevalence among hospital population, although ‘prevalence data’ reported for population of patients admitte d to
the hospital over yearly intervals. See above
3. Trends:
1. Newly identified MRSA patients per 100 admissions initially very low (0.05 in 1989), increasing yearly to 0.57 in 1992 (end of
      phase 1), 0.49 in 1993 and 0.6 in 1994. Subsequently fell each year to reach 0.24 in 1997
2. Cases per 1000 patient days showed a similar pattern, as did MRSA bacteraemias (1 in 1989, peaking at 34 in 1992, then
      falling each year after 1994 to reach 10 in 1997)
3. Total number of MRSA patients per 100 admissions (including previously identified patients) followed a similar pattern of rise
      and fall (from 0.07 in 1989, peaking at 1.42 in 1994, and falling to 0.59 in 1997), but the eventual fall occurred somewhat later
      than that of the other measures. Percentage of MRSA among laboratory isolates also exhibited this lag
4. Secondary outcomes:
1. Hand-hygiene compliance: 6-monthly surveys of compliance rates (Dec. 1994–Dec. 1997). Compliance rose from 47.6%
      (Dec. 1994) to 53.4 (Dec. 1995) to 61.8% (Dec. 1996) to 66.2 (Dec. 1997). Volumes of alcohol handrub used also increased
2. 2. MRSA:MSSA: Annual figures for MRSA as a per cent of total laboratory S. aureus isolates reported for whole study (1989–
      97). MSSA bacteraemias also reported. There was no apparent trend in annual MSSA bacteraemias (range: 78–102)
Economic evaluation: Cost estimates for microbiology, surveillance, contact isolation. Total infection control programme
MRSA strain details: Not reported in papers considered here but PFGE typing.140 Spread due to several epidemic strains
Analysis in paper: Poisson regression used to analyse changes of incidence. Details of regression model not presented
Major confounders and bias: Changes in length of patient stays and bed occupancies. Some account is taken of these by
appropriate choice of denominators, but shorter length of stay may reduce detection of infections.
For outcomes that include patient colonisation, changes in screening practice and effort represent major confounders, but MRS A
bacteraemia data should not be affected by this
What the authors conclude:
1. Infection control measures had a big impact on the MRSA reservoir and bacteraemia attack rate
2. Findings confirm reports of the value of hand-hygiene for MRSA transmission control (although study design precludes
      ascertainment of the proportion of the reduction in the infection rate attributable to the hand-hygiene campaign)
3. Hand-hygiene programme produced a sustained increase in compliance, coinciding with a reduction of MRSA transmission
Assessment of authors’ conclusions:
1. The data provide clear evidence that the number of patients with MRSA and MRSA bacteraemias first stabilised and then fell
      after control measures were implemented. The assertion that the control measures caused the change is highly plausible,
      although there are some potentially important confounding factors
2. It is not possible to tell what effect any single measure had, although the fall in new cases after 1995 is consistent with the
      assertion that reported improved hand-hygiene compliance played an important role
3. 3. Plausible evidence that hand-hygiene programme improved hand-hygiene compliance in a sustained manner
Assessment of Evidence: Stronger evidence supporting control by interventions. Some potential confounders, but these provide
less plausible explanations for the changes