Download Risk Factor - Public Health Wales

Lookback in anguish - the
epidemiological challenges of a
Hepatitis C incident.
Dr Brendan W Mason
Consultant Epidemiologist
Communicable Disease Surveillance
Centre
Advisory Group on Hepatitis
• Patient Notification Exercise (PNE)
– only recommended when HCW to patient
transmission of hepC had been identified
– if a PNE is indicated only patients with high
risk exposure prone procedure (EPP) notified
in the first instance
October 2005
• HCW with RNA positive hepC infection
• HCW currently working dental surgery
• Action
– Set up Incident Management Team
– Look for evidence possible HCW to patient
transmission hepC from existing records
– Review LHB records on dental surgery
including practice inspections.
Evidence transmission hepC
• Ideally
– compare named patients treated by HCW with
named notification data
– Investigate any known cases hepC to
determine source infection
• Reality
– Practice not computerised, private practice no
access to records
– Mapping of known cases in LHB showed no
clustering around dental practice
Review LHB Records
• Practice inspections - concerns (never resolved)
about infection control
• Two written patient complaints (5 years apart)
about infection control
• Deficiencies in infection control practice over a
ten year period included a failure to:
– wear gloves while performing EPPs;
– employ a tray system for sterilising instruments;
– wrap or separate instruments after sterilisation.
UKAP advice
• UK Advisory Panel for health care workers
infected with Blood-borne Viruses (UKAP)
• Infection control appears to have been
substandard
– Risk transmission of hepC from HCW to patients
– Risk of transmission of BBVs between patients,
• All the HCWs patients should be contacted and
offered testing for HIV, hepB and hepC
Infection Control Failures
• No UK guidance on patients exposed to
instruments possibly contaminated with
Blood Borne Viruses (BBVs)
• Local Risk assessment to determine need
for Patient Notification Exercise (PNE)
• Advice on risk patient to patient
transmission not strictly with UKAP remit
The PNE
• Records available 6,139 patients treated
at the practice since 1969.
– 4,900 of these patients contacted
– 1187 patients not traceable
– 652 deceased.
• 2,665 patients responded and tested for
BBVs
Case Control Study
• Unmatched nested case control study
• Test the null hypothesis that treatment by
the HCW was not associated with infection
with a BBV
• Four controls per cases gave power of
75% at the 5% significance level to detect
a 50% greater mean number of
attendances for treatment in cases
compared to controls.
Methods
• Cases
– individual with laboratory evidence of current
or past infection with a BBV identified as a
result of the PNE.
• Controls
– randomly selected individual tested as a result
of the PNE without laboratory evidence of
current or past infection with a BBV
Methods: case note review
• Age, gender, total number treatment episodes
• Each treatment episode
• Date
• Non invasive care only or clinical examination and/or
operative procedure
• Operative procedure
•
•
•
•
•
•
non-surgical periodontal treatment
injection local anaesthetic
restorative procedure
extraction of teeth
minor oral surgery
other minimally invasive procedures
Methods: telephone interview
• Social history: place of birth; ethnicity; living outside
UK; incarceration; residential accommodation; living
person BBV; hepB status mother; tattoos; body piercing.
• Occupational history: work in health care; work in
residential accommodation; and, work outside the UK.
• Medical history: organ transplants or tissue grafts; renal
dialysis; hospital or dental treatment abroad; hepatitis B
immunisation; surgical treatment; blood transfusion;
receipt other blood products.
• Sexual history: number of lifetime partners; gender of
sexual partners; condom use; partners IVDU.
• Drug history: injecting, snorting or other drug use:
injecting in the presence of others; sharing needles,
syringes or ‘works’; sharing spoons, water, filters, or
‘paraphernalia’.
Results
• 30/2665 patients evidence BBV infection
– HepC infection (past or present) 11 patients
– Past HepB infection 20 patients.
– No current infection Hep B
– No HIV
• Prevalence
– HepC 0.41% (95% CI 0.21% - 0.74%)
– Past HepB 0.75% (95% CI 0.46% - 1.16%).
Results
• Response rate interviews
– 83 % (25/30) cases
– 56% (67/120) controls.
• All patient records available for review.
– Mean age cases 57 vs controls 55 (p=0.57).
– 47% cases vs 36% controls male (p=0.27).
• Mean number of attendances for treatment was
20.5 in cases and 18.6 in controls
• Difference 1.8 (95% CI -5.4 to 9.1) not
statistically significant (p=0.62).
Results: virology HepC
Case
Genotype
Sequencing
1
1
Different from cases 3, 5, and 11
2
Not available
Declined testing
3
1a
Different from cases 1, 5 and 11
4
Mixed
Sample unsuitable
5
1a
Different from cases 1, 3, and 11
6
2
No other genotype 2
7
Not available
Not viraemic
8
3a
Different from HCW and case 9
9
3a
Different from HCW and case 8
10
Not available
Not viraemic
11
1a
Different from cases 1, 3 and 5.
Alternative Risk
Factors*
Yes
Yes
Yes
Yes
*The presence of alternative risk factors are only identified when virus was not available for sequencing.
Number episodes dental treatment
cases hepatitis C
Mean number episodes
Treatment
Cases
(n=11)
Controls
(n=120)
Difference
95% CI
P
Attended surgery
20.2
18.6
0.9
-9.4, 12.5
0.78
Clinical examination
10.5
9.7
1.1
-5.3, 7.1
0.78
Any procedure
15.5
13.4
2.1
-6.1, 10.3
0.62
Restorative procedure
8.9
7.5
1.5
-3.7, 6.6
0.58
Periodontal procedure
4.2
3.0
1.1
-1.4, 3.6
0.39
Extraction
1.3
1.0
0.2
-0.8, 1.2
0.65
Minor surgery
0
0.2
0.2
-0.5, 0.1
0.24
Risk factors Hepatitis C Infection
Risk Factor
Cases (n=8)
Controls (n= 67)
Exposed
Exposed
Odds
Ratio
95% CI
P
Yes
No
Yes
No
Lived with case hepatitis C
1
7
0
67
∞
0-∞
0.11
Inmate prison / detention centre
1
7
0
67
∞
0-∞
0.11
Worked health care
3
5
11
56
3.1
0.4 - 18
0.16
Injected drugs
5
3
0
67
∞
22 - ∞
0.0001
Snorted drugs
3
5
1
66
40
2.4 - 2107
0.003
Sexual partner IV drug user
3
5
1
66
38
2.3 - 2044
0.003
Over 10 sexual partners
4
4
11
56
5.1
0.8 - 31
0.046
Tattoo
0
8
6
61
0
0 – 5.4
1.0
Ears pierced
6
2
41
26
1.9
0.3 - 20
0.70
Blood product before 1991
1
7
11
56
0.7
0 – 6.7
1.0
Surgery
7
1
56
11
1.4
0.1 - 68
1.0
Hospital treatment outside UK
2
6
5
62
4.1
0.3 - 32
0.16
Number episodes dental
treatment cases hepatitis B
Mean number episodes
Treatment
Cases
(n=20)
Controls
(n=120)
Difference 95% CI
P
Attended surgery
19.9
18.6
1.2
-7.5, 9.9
0.78
Clinical examination
10.8
9.7
1.1
-3.7, 6.1
0.65
Any procedure
14.6
13.4
1.2
-5.4, 7.7
0.73
Restorative procedure
7.0
7.5
-0.5
-4.4, 3.5
0.82
Periodontal procedure
4.3
3.1
1.2
-0.9, 3.3
0.26
Extraction
1.7
1.0
0.7
-0.2, 1.5
0.14
Minor surgery
0
0.2
-0.2
-0.4, 0.05
0.12
Risk factors Hepatitis B Infection
Cases (n=18)
Controls (n= 67)
Exposed
Exposed
Yes
No
Yes
No
Born outside UK
4
14
2
Ethnic origin high prevalence
2
16
Lived with case hepatitis B
2
Worked residential home
Risk Factor
Odds
Ratio
95% CI
P
65
9.3
1.2 - 108
0.005
0
67
∞
2.0 - ∞
0.006
16
0
67
∞
2.0 - ∞
0.006
5
13
2
65
12.5
1.7 – 138
0.0007
Injected drugs
2
16
0
67
∞
2.0 - ∞
0.006
Snorted drugs
2
16
1
66
8.3
0.4 - 494
0.11
Sexual partner IV drug user
2
16
1
66
8.3
0.4 - 494
0.11
Over 10 sexual partners
6
12
11
56
2.5
0.6 – 9.3
0.18
Men sex men
1
17
0
67
∞
0-∞
0.05
Tattoo
2
16
6
61
1.3
0.1 – 8.0
0.78
Ears pierced
8
10
41
26
0.5
0.2 – 1.7
0.20
Blood product before 1970
1
17
2
65
1.9
0.03 - 38
0.52
Surgery
14
4
56
11
0.7
0.2 – 3.4
0.57
Discussion: HepC
• Prevalence hepC 0.41% similar to UK
estimates 0.5%
• No association between number or type of
dental treatment and infection
• Genetic sequencing ruled out HCW to
patient and patient to patient transmission.
• Alternative explanations in patients who
not viraemic established
Discussion: HepB
• Prevalence past hepB, 0.76%, similar or lower than other
estimates in literature
• No association between number or type of dental
treatment and infection
• Alternative explanation 9 of 18 cases hepB
– 2 IVDU; 2 ethic origin/born high prevalence country; 1 MSM;
sexual partner known hepB; 2 residential homes learning
difficulties; 1 history jaundice after blood transfusion before 1970.
• Odds ratio of 2.5 > 10 sexual partners ? heterosexual
transmission
• Similar other UK studies - probable means of acquisition
known half adult cases of acute HepB infection
Conclusion
• In absence prior evidence of transmission
the PNE would not have been undertaken
if recommended infection control practice,
in particular the consistent use of gloves
while performing EPPs, has been
implemented by the HCW.
Conclusion
• Patient to patient transmission BBV not
demonstrated despite extensive virological
and epidemiological investigation.
• In incidents where transmission has not
been identified the risk of patient to patient
transmission is very low.
• Practice with respect to PNEs following
infection control failures varies within the
NHS.
Conclusion
• NPHS risk assessment concluded risk of patient
to patient transmission of a BBV infection was
probably very small but not zero.
• Assessment reliant on low prevalence of BBV
infections in the relevant community rather than
safety infection control procedures in operation.
• Extensive virological and epidemiological
investigation demonstrated that assumptions
underpinning risk assessment were correct.
Conclusion
• Minimal health gain
– 5 new cases current HepC infection who may
benefit from treatment
– Advice to reduce onward transmission
• Significant costs
– LHB, NPHS, Trust, Lab.
• Patient views
– Anxiety on receiving letters
– Believe that patients should be informed
Recommendations
• Clinical Governance / Practice Inspection
must prevent infection control failures
• National Institute for Health and Clinical
Excellence should produce guidance for
the NHS on PNE following infection control
failures
– combine a robust economic evaluation with
the views of stakeholders including patients.