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 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

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 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% - 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 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.

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

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 0.4 - 18 0.16 Injected drugs 22 - ∞ 0.0001 Snorted drugs 66 40 2.4 - 2107 0.003 Sexual partner IV drug user 38 2.3 - 2044 Over 10 sexual partners 4 5.1 0.8 - 31 0.046 Tattoo 8 6 61 0 – 5.4 1.0 Ears pierced 2 41 26 1.9 0.3 - 20 0.70 Blood product before 1991 0.7 0 – 6.7 Surgery 1.4 0.1 - 68 Hospital treatment outside UK 62 4.1 0.3 - 32

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

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 1.2 - 108 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 0.4 - 494 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 0.03 - 38 0.52 Surgery 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 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

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.