1. Lookback in anguish - the epidemiological challenges of a Hepatitis C incident.
Dr Brendan W Mason
Consultant Epidemiologist
Communicable Disease Surveillance Centre

2. 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

3. 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.

4. 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

5. 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.

6. 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

7. 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

8. 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

9. 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.

10. Methods Cases Controls
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

11. 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

12. 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’.

13. Results 30/2665 patients evidence BBV infection Prevalence
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% %)
Past HepB 0.75% (95% CI 0.46% %).

14. 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).

15. Results: virology HepC
Case
Genotype
Sequencing
Alternative Risk Factors* 1
Different from cases 3, 5, and 11 2
Not available
Declined testing
Yes 3 1a
Different from cases 1, 5 and 11 4
Mixed
Sample unsuitable 5
Different from cases 1, 3, and 11 6
No other genotype 2 7
Not viraemic 8 3a
Different from HCW and case 9 9
Different from HCW and case 8 10 11
Different from cases 1, 3 and 5.
*The presence of alternative risk factors are only identified when virus was not available for sequencing.

16. 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
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
-1.4, 3.6
0.39
Extraction
1.3
1.0
0.2
-0.8, 1.2
0.65
Minor surgery
-0.5, 0.1
0.24

17. Risk factors Hepatitis C Infection
Cases (n=8)
Controls (n= 67)
Odds Ratio
95% CI P
Exposed
Yes No
Lived with case hepatitis C 1 7 67 ∞
0 - ∞
0.11
Inmate prison / detention centre
Worked health care 3 5 11 56
3.1
0.16
Injected drugs
22 - ∞
0.0001
Snorted drugs 66 40
0.003
Sexual partner IV drug user 38
Over 10 sexual partners 4
5.1
0.046
Tattoo 8 6 61
0 – 5.4
1.0
Ears pierced 2 41 26
1.9
0.70
Blood product before 1991
0.7
0 – 6.7
Surgery
1.4
Hospital treatment outside UK 62
4.1

18. 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
-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
-0.9, 3.3
0.26
Extraction
1.7
1.0
0.7
-0.2, 1.5
0.14
Minor surgery
0.2
-0.2
-0.4, 0.05
0.12

19. Risk factors Hepatitis B Infection
Cases (n=18)
Controls (n= 67)
Odds Ratio
95% CI P
Exposed
Yes No
Born outside UK 4 14 2 65
9.3
0.005
Ethnic origin high prevalence 16 67 ∞
2.0 - ∞
0.006
Lived with case hepatitis B
Worked residential home 5 13
12.5
1.7 – 138
0.0007
Injected drugs
Snorted drugs 1 66
8.3
0.11
Sexual partner IV drug user
Over 10 sexual partners 6 12 11 56
2.5
0.6 – 9.3
0.18
Men sex men 17
0 - ∞
0.05
Tattoo 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
1.9
0.52
Surgery
0.7
0.2 – 3.4
0.57

20. 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

21. 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

22. 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.

23. 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.

24. 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.

25. Conclusion Minimal health gain Significant costs Patient views
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

26. 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.