Should Genotypic Resistance Testing Be Performed for All Treatment-naive
HIV Patients?
The utility and cost effectiveness of HIV drug resistance testing
for HIV patients with no prior antiretroviral treatment has been
debated for years. Data from studies now show that in the US
and Europe treatment-naïve HIV patients have a population prevalence
of baseline drug resistance of 8-10%.
Researchers at Harvard and Brigham Young Universities (BYU) say their recent
study data demonstrate that the use of genotypic testing
among treatment naïve patients with chronic
HIV infection is not only cost effective but also
likely to improve clinical outcomes compared to outcomes among
other, similar patients without this type of care. Authored by
Paul Sax and others, the Harvard-BYU study results appear in the
November 1, 2005 issue of Clinical Infectious Diseases
[1].
The
investigators used a state-transition model of HIV
disease to project life expectancy, costs, and
cost-effectiveness in a hypothetical cohort of antiretroviral-naive
patients with chronic HIV infection. On the basis
of a US
survey of treatment-naive patients from the
US Centers for Disease Control
and Prevention, they used a baseline
prevalence of drug resistance of 8.3%.
Results
Genotype-resistance testing at initial diagnosis
of HIV infection increased per-person quality-adjusted
life expectancy by 1.0 months, with an incremental
cost-effectiveness ratio of $23,900 per quality-adjusted
life-year gained, compared with no genotype testing.
The cost-effectiveness ratio for resistance testing
remained less than $50,000 per quality-adjusted life-year
gained, unless the prevalence of resistance was
</= 1%, a level lower than those reported
in most regions of the US and Europe.
In
sensitivity analyses, the cost-effectiveness remained
favorable through wide variations in baseline assumptions,
including variations in genotype cost, prevalence
of resistance overall and to individual drug classes,
and sensitivity of resistance testing.
Discussion
The
researchers analysis suggests that with a baseline
prevalence of resistance of >1%, resistance
testing at the time of HIV diagnosis is
a cost-effective strategy that can lead
to selection of a more effective initial antiretroviral
regimen and likely longer survival
for patients who have drug-resistant virus.
The
$400 cost of the one-time test makes primary resistance testing
very cost effective, because of the high cost of treatment for
HIV during a patient’s lifetime. The researchers found that the
cost-effectiveness of primary resistance testing
increases with the prevalence of resistance.
In
conclusion, the authors write, “On the basis of the
available evidence, and considering both clinical
benefits and costs, genotype resistance testing
should be performed for all patients [emphasis
added—Ed] with newly diagnosed HIV infection in the
United States, with the results used to
guide the choice of antiretroviral regimen when
treatment is indicated.”
“Resistance
testing at the time of diagnosis should be the standard of care,”
they conclude.
In
an editorial accompanying the article Sax et al, Frederich Hecht
and Robert Grant of the HIV/AIDS Division at San
Francisco General Hospital
endorse the proposed recommendation to use genotypic
drug-resistance testing for all drug-naive patients
in most settings. Hecht and Grant conclude, “The recommendation
of genotypic resistance testing for all drug-naive
persons with HIV is more easily implemented,
and the article by Sax et al shows that
it is also cost-effective.” [2]
The
take-home message from the Sax et al study results and the Hecht
and Grant editorial is that it’s time to make the change from
earlier recommendations for resistance testing (in
1998) that cautiously endorsed its use for patients
with treatment failure or
possibly those recently infected with HIV infection
[3].
Division
of Infectious Diseases, Brigham
and Women's Hospital, Divisions
of General Medicine and Infectious
Diseases, Massachusetts General
Hospital, Harvard Medical School,
Harvard Center for Risk
Analysis, Harvard School of
Public Health, and Departments
of Biostatistics and Epidemiology,
Boston University School of
Public Health, Boston, Massachusetts.
10/07/05
References
1.
P E Sax and others. Should Resistance Testing Be
Performed for Treatment-Naive HIV-Infected Patients? A Cost-Effectiveness
Analysis. Clinical Infectious Diseases 41(9): 1316-1323.
November 1, 2005.
2. F Hecht and R Grant. Resistance Testing
in Drug-Naive HIV-Infected Patients:
Is it Time? Clinical
Infectious Diseases 41(9): 1324-1325. November
1, 2005.
3.
M S Hirsch and others. Antiretroviral drug resistance testing in
adults with HIV infection: implications for clinical management.
International AIDS Society
USA Panel. JAMA
279:198491. 1998.
