Transcript The value of male HPV vaccination in preventing cervical

The value of male HPV vaccination in
preventing cervical cancer and genital warts
in a low resource setting
Monisha Sharma, Stephen Sy, Jane J. Kim
Center for Health Decision Science
Harvard T.H. Chan School of Public Health
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Scenario
At a conference on cervical cancer prevention, a speaker
presented data on the cost-effectiveness of HPV vaccination for
girls in Thailand (see BJOG. 2012;119(2):166-76).
An audience asked, “Would vaccinating both boys and girls be
better than vaccinating girls only?”.
Background
• Cervical cancer (CC) leads to significant mortality and
morbidity in low, middle-income countries (LMICs)
• In LMICs, CC screening coverage is low and of variable
quality due to the lack of resources and infrastructure
• HPV vaccination has shown promise as a primary prevention
strategy to reduce CC
• The cost-effectiveness and appropriate target population of
HPV vaccination in LMICs are to be elucidated
• South Vietnam has high CC incidence (26/100,000 personyears) and low (<5%) CC screening coverage
Background
• What is the incidence of cervical cancer in
your country?
• What are the uptake rates of cervical
screening and HPV vaccine in your country?
• What is GAVI Alliance? How does it achieve its
goals? (http://www.gavi.org/about/)
The Research Question
In LMICs, is HPV vaccination of both
girls and boys cost-effective compared
to vaccinating girls only?
Description of Research (PICOD)
Participants
Male and female population (≥ 9 years old) in South
Vietnam
Intervention
HPV vaccination for both male and female
Comparison
HPV vaccination for female only
Outcomes
Economical costs, estimates of cervical cancer and genital
warts incidence, mortality and quality-adjusted life years
(QALYS)
Study Design
Economic evaluation using mathematical models
Methods
• Mathematical models were used to
– Simulate the dynamic transmission of HPV infection
– Estimate cervical cancer and genital warts cases
– Estimate costs associated with different scenarios of HPV
vaccination and cervical screening coverage
• Models were calibrated to epidemiologic data from South
Vietnam at different HPV vaccine costs and cervical cancer
screening coverage rates
• Main outcome measures: incremental cost-effectiveness
ratios (ICERs), i.e. cost per quality-adjusted life year (QALY)
gained
Overview: Mathematical Models
Infection1
Clearance
1
Progression2
HPV
Infected
Regression
Incidence of infection depends on age, HPV type, prior infection, and type-specific immunity.
Progression of HPV infection and CIN 1 depends on age and HPV type.
3 Cancer states stratified by stage (local, regional, distant) and detection status (undetected, symptomdetected, screen-detected).
4 Death can occur from all-cause mortality from every health state and excess cancer-specific mortality
from cancer states.
2
Methods
• What are the advantages and disadvantages of
using a mathematical model to address this
research question?
• What are the alternative approaches to answer
this research question?
• Critically appraise this study using the CASP
checklist for economical
evaluation:http://bit.ly/1EX0KXE
Incremental cost-effectiveness ratios by cost per
vaccinated adolescent and vaccination coverage*
Mean
cancer
reduction
Cost per vaccinated individual
I$10
I$25
I$50
I$75
(I$2 per dose)
(I$5 per dose)
(I$10 per dose)
(I$15 per dose)
25% Coverage
Natural history
Vaccination, girls only
Vaccination, girls and boys
-20.0%
22.7%
----------CS
$49
----------CS
$572
----------$211
$1,445
----------$454
$2,317
75% Coverage
Natural history
Vaccination, girls only
Vaccination, girls and boys
-50.2%
52.9%
----------CS
$280
----------CS
$1,153
----------$252
$2,608
----------$515
$4,062
90% Coverage
Natural history
Vaccination, girls only
Vaccination, girls and boys
-56.9%
58.2%
----------CS
$519
----------CS
$1,751
----------$253
$3,806
----------$517
$5,860
*Outcomes: CC and genital warts. Bolded: scenarios where HPV vac of boys is <Vietnam’s GDP per capita (I$2,800); shaded:
strategies where HPV vac of boys <50% Vietnam’s GDP per capita; “CS”: strategies that were cost-saving compared to no
intervention. Natural history: No CC screening or HPV vaccination. Mean cancer reduction: Compared to natural history
Sensitivity analysis for ICERs
for vaccinating girls and boys
(at I$5/dose)
Impact of varying assumptions on ICERs of vaccinating girls and boys vs. vaccinating girls alone in South
Vietnam at different coverage levels for vaccine costs of I$5 per vaccinated adolescent. Red dashed lines:
ICER threshold of Vietnam’s GDP per capita. Black dashed lines: 50% of Vietnam’s GDP per capita.
Results
• Using this study as an example, explain what is
incremental cost-effectiveness ratio (ICER).
• What is the purpose of sensitivity analysis in
economical evaluations?
• What is your interpretation of the results
presented?
Authors’ summary of results
• Vaccination of boys would yield an additional of ≤3.6%
absolute cervical cancer risk reduction, compared to
vaccinating girls alone
• HPV vaccination of boys at I$10/dose was cost-effective
at or below 75% screening coverage using a threshold of
Vietnam’s GDP per capita (I$2,800).
• At a lower threshold of 50% of Vietnam’s GDP (I$1,400),
vaccinating boys was not cost-effective at >I$5/dose.
• Results were robust to sensitivity analyses.
Discussion
• Where may the results of this study be
generalisable?
• What may influence how policy makers utilise
findings of economical evaluations?
• How can researchers maximise the potential of their
research being utilised for health policy decisionmaking?
• Should we give HPV vaccines to all boys in LMICs?
Authors’ conclusions
• HPV vaccination of boys provides some benefit over
vaccinating girls only to reduce cervical cancer and
genital warts.
• HPV vaccination of boys may be cost-effective at low
vaccine costs
• Strategies focusing on achieving high HPV vaccine
coverage for girls may be more efficient in low resource
settings
Limitations of this study
• This analysis only considered health benefits from
prevention of CC and genital warts. We did not consider
other HPV-related cancers including oropharyngeal, anal,
penile, vaginal, and vulvar cancer.
• What effect would the inclusion of these cancers have on
the ICERs for vaccinating boys and girls?
Suggested reading
•
Cohen DJ, Reynolds MR. Interpreting the results of cost-effectiveness studies. J Am Coll
Cardiol. 2008 Dec 16;52(25):2119-26.
•
Husereau D, Drummond M, Petrou S, Carswell C, Moher D, Greenberg D, Augustovski F,
Briggs AH, Mauskopf J, Loder E; CHEERS Task Force. Consolidated Health Economic Evaluation
Reporting Standards (CHEERS) statement. BMJ. 2013 Mar 25;346:f1049.
•
Gold M. Pathways to the use of health services research in policy. Health Serv Res. 2009
Aug;44(4):1111-36.
•
Haynes AS, Gillespie JA, Derrick GE, Hall WD, Redman S, Chapman S, Sturk H. Galvanizers,
guides, champions, and shields: the many ways that policymakers use public health
researchers. Milbank Q. 2011 Dec;89(4):564-98.
•
Linhares IM, Witkin SS. HPV vaccination: unanswered questions remain. BJOG. 2015
Jan;122(1):118.
•
Sharma M, Ortendahl J, van der Ham E, Sy S, Kim JJ. Cost-effectiveness of human
papillomavirus vaccination and cervical cancer screening in Thailand. BJOG. 2012
Jan;119(2):166-76.
Authors’ affiliations
Monisha Sharma
University of Washington, Department of Epidemiology, 1959 NE
Pacific Street, Seattle, WA 98195, USA; [email protected]
Stephen Sy and Jane J. Kim
Department of Health Policy and Management, Center for Health
Decision Science, Harvard T.H. Chan School of Public Health, 718
Huntington Avenue, 2nd Floor, Boston, MA 02115, USA
MS, JJK and SY have no conflicts to declare.
Acknowledgement
• The authors would like to acknowledge the
contributions of the cervical cancer prevention
team at the Center for Health Decision Science at
the Harvard T.H. Chan School of Public Health.
• This study was funded by the Bill & Melinda Gates
Foundation (30505).
• The funders had no role in the study design, data
collection and analysis, decision to publish, or
preparation of the article.