Lookback in anguish - the epidemiological challenges of a Hepatitis C incident.

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 • 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 • 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%).

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

16. Number episodes dental treatment cases hepatitis C

18. Number episodes dental treatment cases hepatitis B

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 • 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.