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Intensified TB case-finding: still wide open to questions and answers

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Intensified TB case-finding: still wide open to questions and answers

Intensified TB case-finding: still wide open to questions and answers

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  • 1. Intensified TB case-finding: still wide open to questions and answers Dr Liz Corbett Bloomsbury Wellcome Trust Centre & Clinical Research Unit, London School Hygiene Tropical Medicine Biomedical Research & Training Institute, Harare
  • 2. Pre-DOTS era
    • ICF widely used in all continents
      • Mass mini-radiographs and household enquiries
      • Diagnosis and treatment +/- sanatoria
      • Still used in some settings today
    • Use associated with declining TB incidence rates in many settings
    • Not formally evaluated as an isolated intervention
  • 3. Kolin
    • 1961 – 1972 Kolin study
      • 5 rounds of MMR
      • Point prevalence of s+ TB fell from 233 to 56 per 100k
      • Incidence of s+ TB fell from 142 to 52 per 100k per year
      • Effective TB treatment introduced + BCG
    • 72% of all cases detected between MMR rounds through passive CFT
    • More effective to focus on effective treatment of cases presenting passively
  • 4. India
    • Tumkur District prevalence survey 1960s (TST and CXR)
      • No TB treatment programme
    • Follow-up investigation for symptoms (?delay)
      • 70% of smear-positive patients aware of symptoms
      • 50% had already sought care
    • Bangalore
      • CXR versus CXR plus symptom screen
        • Symptoms added little to CXR
        • Symptoms alone identified 70% culture-positive TB patients
    Banerji D, Anderson S. A sociological study of awareness of symptoms among persons with pulmonary tuberculosis. Bull Wld Hlth Org 1963; 29:665-683. Gothi GD, et al. Estimation of prevalence of bacillary tuberculosis on basis of chest x-ray and-or symptomatic screening. Indian J Med Res 1976; 64(8):1150-1159.
  • 5. Kenya
    • Case-finding studies in 1970s and 1980s
      • House-to-house surveys most effective
        • 80% of cases had been to clinic with symptoms
        • Distance to clinic
      • Interview of village elders ineffective
      • Mothers asked to refer anyone with symptoms in their household
        • High yield in those who attended
        • Low population impact (4% all cases)
  • 6. Korea
    • Routine use of “school leavers” for door-to-door enquiry
      • Each employee covered 10,000 pop
      • Over 50% of cases picked up this way during 1970s
  • 7. Community-wide p reventive therapy: Bethel ARI (%) & incidence rates / 100 000 pop p.a. 0% 5% 10% 15% 20% 25% 30% 1954 1957 1960 1963 1966 1969 1972 500 1,000 1,500 2,000 2,500 3,000 ARI TB incidence Passive & intensified CFT & BCG INH RCT: 42% pop INH 12mos INH all residents
  • 8. Other studies
    • Toman (1976)
      • 75% of cases self-presenting in countries covered by MMR programmes
      • Netherlands – annual CXR (2.5 million adults)
        • 15% of s+ and 25% of c+ TB detected through MMR
      • Expensive, not cost-effective
      • Assumes equal public health impact of ACF & PCF pick-up
    Toman K. Mass radiography in tuberculosis-control. Who Chronicle 1976; 30(2):51-57
  • 9. Fate of pulmonary TB treated under routine conditions
    • High rates of treatment failure and recurrence
    • Increasing recognition of the importance of adequate treatment
    • First priorities:
      • Effective diagnosis in patients presenting passively
      • Effective treatment of those presenting passively
      • Don’t waste money and risk overwhelming health systems with ICF until these basics are in place  DOTS
  • 10. ICF in the DOTS era
    • Low case-detection a major factor limiting TB control
      • Patients with symptoms cannot access investigations
      • Marginalised populations
      • Not all TB is highly symptomatic
    • HIV-associated TB
      • Driving up global incidence rates
      • High prevalence of active TB in HIV care settings
      • High mortality rates
    • Modeling the impact of better case-finding
    • Time ripe to reconsider ICF
  • 11. ICF goals
    • Reduce morbidity and mortality
      • More intensive case-finding leads to fewer TB deaths and less severe post-TB complications
      • Focus on those most at risk of severe morbidity
    • Reduce TB transmission
      • General community
      • Institutional settings
      • Marginalised populations
    • Increase case-finding
      • Target high risk groups
      • Community-wide approach
  • 12. ICF challenges
    • Poor treatment outcomes
      • Patients detected through ICF unwilling to be treated
      • ICF in settings of high primary MDR-TB
    • Diagnostic approach
      • Active versus inactive TB
      • Relatively low % smear-positive cases
        • Choice of screening and diagnostic tests
      • Illnesses other than TB
        • OIs & HIV itself
    • Overwhelm the health system
  • 13. Cohort study Prevalence study snap shot in time Time (person years) Incidence and prevalence linked by duration of disease
  • 14. Prevalent TB disease
    • High ratio of prevalent: incident disease among HIV-ves
      • See next slide
    • Risk groups for prevalent TB disease
      • Household contacts
      • Homeless
      • IDU
      • VCT attenders
      • Home based care
      • Congregate settings: prisons and miners
      • Old age and male sex
  • 15. Prevalence: incidence
  • 16. Can have prolonged HIV/TB with minimal symptoms: duration of smr+ before diagnosis
  • 17. What do we need to know?
    • ICF in high HIV prevalence populations
      • Screening algorithms
        • Expect these to vary by HIV status
        • Expect these to vary by effectiveness of DOTS
      • Can ICF substantially improve TB control?
    • ICF and treatment outcomes
      • High and low MDR-TB settings
      • IDU
    • Better understanding of prevalent TB disease
      • Impact of HIV
      • Why is prevalent TB so common in HIV-ve pops?
      • Does IPT increase risk of prolonged TB excretion
  • 18. What do we need to know?
    • Targeted ICF: how to do it better
      • Strategies to reach high risk populations (Tables1 & 2)
        • High risk of TB morbidity
        • High risk of prevalent active TB
      • Strategies accessible by the general population
        • ZAMSTAR
        • TB screening clinics akin to VCT clinics
        • TB screening clinics accessible only on referral
      • Involving the community
        • TB clubs / shop keepers / home based care
      • Linked to better management of smear-negative TB
  • 19. Institutional TB
    • How much TB is institutionally acquired?
      • TST conversion in student nurses
        • 18% p.a. strict US criteria after negative 2-step in Harare
          • Will have parallel ELISPOT data
        • ? 10+% annual risk of TB disease if HIV+ve
      • HIV care patients
        • Recurrent TB disease in patients on ARVs
        • Gold miners:
          • recurrent TB increased from ~8% p.a to ~25% p.a. in HIV+
          • Coincided with introduction of HIV care clinic
    • Can ICF control institutional TB transmission?
      • Long term preventive therapy?
      • Role of culture-based ICF
  • 20. Ongoing research
    • Shop keepers: Malawi
    • ZAMSTAR
    • DETECTB
    • Cambodia
    • Kenya
    • Others?
    • Institutional TB: ARTI in student nurses
      • Others?
  • 21. Recommended priority groups for targeted ICF
    • VCT clients
    • HIV care clinics
    • Patients starting ARVs (IRIS)
    • Household contacts
    • IVDU
    • Institutions
      • Prisons
      • hospitals
  • 22. General population screening
    • Insufficient evidence on which to base recommendations
      • Potential HUGE: true TB prevention
      • Impact of a single round or brief period of highly effective population-based ICF?
        • DOTS can be the sustainable element (Bethel0
        • One passive = one ICF patient?
        • Respective roles of reactivation and recent TB infection
    • Effective screening tool: digital MMR??
    • Effective diagnostic test
    • Effective case-management
      • Note that in high HIV prevalence settings the ratio of prevalent to incident cases may not be all that high
      • Would expect a rapid impact on new TB cases if prevalent TB disease control is improved
  • 23. Conclusions
    • ICF is natural extension of DOTS
      • Operational research priorities & interim recommendations – p 7
      • Targeted linked to IPT and ARVS
        • VCT clients
        • Institutional TB control
        • Household contact screening
        • IDUs
      • General populations: model / demonstration programmes?
        • TB screening clinics
        • Shop-keepers
        • ZAMSTAR approach
        • Household screening
        • MMRs
    • TB case-finding is HIV case finding
      • Chronic cough patients in Harare
        • HIV prevalence 83% overall: 88% in TB patients