maximizing the impact of smear microscopy · all patients who are capable of producing sputum and...
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J. Lucian (Luke) Davis, MD, MAS Division of Pulmonary & Critical Care Medicine
San Francisco General Hospital July 10, 2013
Maximizing the impact of smear microscopy
McGill Advanced TB Diagnostic Research Course
Roadmap
Estimated vs. Notified Cases
Case Detection Rate (%) 1995-2010
MDG target
0
20
40
60
80
100
1995 2000 2005 2010Global Africa
• TB patients are diagnosed but not reported
• TB patients do not seek care
• TB patients seek care but are not diagnosed
– Diagnostics have low sensitivity or long turn-around time – Poor TB evaluation practices
Three reasons for low case detection rates
WHO Global TB Report 2010
The TB diagnostic funnel
Seek care for symptoms of TB
Seek care at a microscopy center
Get referred for smear examination
Test smear-positive
Start treatment
All with unexplained cough
Diagnosed & treated TB patients
TB evaluation guidelines
Standard 1. All persons with otherwise unexplained productive cough lasting 2-3 weeks or more should be evaluated for tuberculosis.
Standard 2. All patients who are capable of producing sputum and suspected of having pulmonary tuberculosis should have at least two sputum specimens submitted for microscopic examination in a quality-assured laboratory.
Standard 8. All patients diagnosed with TB should receive an internationally accepted first-line treatment regimen.
Hopewell P. Lancet. 2006
International Standards for Tuberculosis Care (ISTC)
Uganda TB Surveillance Project
• Network of 6 government health centers
• Partners – Uganda Ministry of Health – Makerere University
• Electronic data collection (>100,000 visits/year)
• Web-interface to monitor indicators tied to ISTC
Patient demographics
Cough history
TB exams
TB diagnoses
TB medications
ISTC Quality Indicators
Cough >/= 2 weeks
Sputum AFB Ordered
Sputum AFB Completed
AFB Smear-Positive
TB Treatment
>/= 2 Negatives >/= 1 Positive
TB Evaluation Algorithm
Total episodes of care
Proportion Receiving ISTC-adherent Care
Indicator
1
2
3
Objective 1: “Define quality gap”
Q1 2009 (14,852 patients 365 TB suspects) Standard 1: Referred for TB testing 21% Standard 2: Completed TB testing (if referred) 71% Standard 3: Treated for TB (if smear-positive) 73% ISTC-adherent care 11%
Davis et al. AJRCCM 2011
ISTC, International Standards for TB Care
WHO smear microscopy policy, 2008
• Eliminating 3rd smear – ~33% decrease in technician time and in supply costs – ~70% increase in case detection from better microscopy
• Does not address high costs to patients Katamba A et al Int J Tuberc Lung Dis 2007 Cambanis A et al Int J Tuberc Lung Dis 2007
500 patients with possible TB 100 with AFB+ TB
1st Sputum
2nd Sputum
3rd Sputum
Number of slides examined 500 413 402
Incremental cases per slide examined 87 11 2
Number needed to diagnose AFB+ 6 38 201
Objective 2: “Understand quality gap” • Conceptual Model: Theory of Planned Behavior
• Data collection – Key informant interviews (26 interviews completed) – Field Observation
• Analysis – Transcribe interviews and field notes – Apply standard coding scheme to identify recurring themes
ISTC, International Standards for TB Care
PRECEDE framework Recurring themes
Predisposing factors (Knowledge, attitudes, beliefs, intention)
•Low motivation of staff • Inconsistent training of staff
“Some of us are trained, but some new staff are not trained.”
Enabling Factors (Factors that if addressed make it easier to initiate the desired behavior)
•Workload faced by lab staff •Multi-day sputum collection and evaluation
“When they have a cough for more than 2 weeks they are sent to the lab. But the problem is they get the first sample and sometimes, actually most times they don’t bring the second sample.”
Reinforcing Factors (Factors that if addressed make it easier to continue the desired behavior)
•Limited capacity for patient follow-up •Lack of communication and coordination between staff
“…actually at times we have met but we don’t meet [regularly], only when we realize there is a problem that’s when we communicate and say why is this happening, then we try to rectify.”
Barriers to TB evaluation
Objective 3: “Improve quality gap”
ISTC, International Standards for TB Care
p=0.005
ISTC-adherent care: 2009 Q1 – Q4
Davis et al. AJRCCM 2011 ISTC, International Standards for TB Care
ISTC-adherent care: 2009 Q1 – Q4
Q1 Q2 Q3 Q4
% getting ISTC-adherent care 11% 22% 37% 34%
New TB patients on treatment 5 13 23 21
Objective 3: “Improve quality gap”
ISTC, International Standards for TB Care
Sample performance feedback report
Trends, interpretation, goal setting
Intervention evaluation
• Design: Quasi-experimental (interrupted time series) • Sites selected to receive intervention in random order • Analysis: Logistic regression with robust standard errors
• Primary predictor: Intervention period (pre vs. post) • Co-variates: Age, gender, secular trend for time
Site 6
Site 5
Site 4
Site 3
Site 2
Site 1
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Post-Intervention Period
CALENDAR TIME
Intervention Control Period
Continuous quality improvement reports
Objective 3: “Improve quality gap”
ISTC, International Standards for TB Care
Same-day TB diagnosis policy
STAG: Logistical & infection control concerns
*STAG:
WHO Strategic
and Technical Advisory
Group
“More programmatic evidence needed…”
Quality impact of optimized smear microscopy
Optimized smear microscopy: Next steps?
Cattamanchi A et al Am J Respir Crit Care Med 2011
Same-day reporting
Davis JL et al. JAIDS 2012
Two WHO policies, two approaches to improving yield
Smear result indicates TB
TB treatment initiated
Smear exam ordered
Inadequate sensitivity
Pre-treatment loss to follow-up
Day 1
Day 1-2
Day 1
Xpert result indicates TB
TB treatment initiated
Xpert done
Inadequate sensitivity
Pre-treatment loss to follow-up
2011: Xpert MTB/RIF
2010: Same-day microscopy
Day 1 Day 2-3
Which has the greatest impact? 1. Same-day diagnosis 2. Regionalized Xpert, or 3. Both?
Compartmental model
Scenarios modeled
* Same-day scaled-up over 2 years to 100% population coverage † Xpert scaled-up over 2 years to 75% population coverage ¶ Xpert over 2 years to 75% coverage, same-day microscopy last 25%
Scenario Sensitivity for AFB- TB
Pre-treatment loss to follow-up
Standard Microscopy 0% 15% Same-day Microscopy* 0% 1.5% Xpert† 72% 15% Same-day Xpert¶ 72% 1.5%
Projected impact on annual TB incidence
Same-day Xpert MTB/RIF
Projected impact on TB mortality
Scenario
Cumulative Mortality # of deaths (millions)
Reduction (%)
Standard Microscopy 4.20 0 Same-day Microscopy 3.70 0.49 (12) Xpert 3.20 1.00 (24) Same-day Xpert 2.81 1.39 (33)
Same-day microscopy provides substantial incremental impact on incidence and mortality (and likely at very low cost)
Smear image
Diagnosis
Community health worker Trained microscopist
Patient District Health Center
Expanding smear access: mobile telemicroscopy
Prototype for field testing
TB bacillus. Image captured using device in direct sunlight.
• Portable, battery-powered fluorescence imaging • Diagnostic quality imaging • Sensitivity and specificity non-inferior (+/- 10%) to
standard LED fluorescence microscopy
Breslauer et al, PLoS One 2009 Tapley et al, J Clin Micro 2013
CellScope – 2nd generation
Automated detection
Mobile phone CellScope Auramine-O
iPhone 4S
Chang et al, MICCAI 2012
The TB diagnostic funnel
Seek care for symptoms of TB
Seek care at a microscopy center
Get referred for smear examination
Test smear-positive
Start treatment
All with unexplained cough
Diagnosed & treated TB patients
Summary • Microscopy offers many opportunities to improve case
detection and patient-centered TB evaluation – Increasing the delivery of high-quality diagnostic services – Shortening the diagnostic process and reducing drop-out – Reducing untreated smear-positive TB in the community
• Better services to individuals at the top of the TB diagnostic funnel will provide much greater gains for TB programs than better diagnostics at the bottom of the funnel
Acknowledgments
Adithya Cattamanchi UCSF
Achilles Katamba Makerere University
William Worodria Makerere University
David Dowdy Johns Hopkins
MIND Team, MU-UCSF Collaboration Uganda TB Surveillance Project Team
Questions?