In another model, Johnson's team looked at quality of
life and survival among people in the same clinical trial population treated
at different fibrosis stages, compared to the interferon-era strategy of 'watchful
waiting' for disease progression (abstract
P0806).
Here, they developed a Markov disease utility
state-transition model to estimate survival benefits over a lifetime horizon
for treated and untreated patients from the perspective of a private US payer,
aiming to quantify and estimate a monetary value for life-years (LYs) and
quality-adjusted life years (QALYs) gained. They used a threshold of US$100,000
per LY or QALY, a common value in health economics studies.
They found that lifetime survival benefits varied
substantially according to the fibrosis stage at treatment initiation. The
value of the survival benefit increased sixfold, from US$61,096 for people
treated at stage F0 to US$372,130 for those treated at stage F4. The
quality-adjusted value of these survival benefits increased nearly threefold, from
US$178,313 at stage F0 to US$482,242 at stage F4.
"Treatment with 3D +/- ribavirin prolongs the
survival of genotype 1 HCV patients and improves quality of life compared to
watchful waiting," they concluded. "The survival costs of watchful
waiting (measured as the differential value of survival with treatment relative
to no treatment) are substantially greater at more advanced levels of liver
fibrosis."
A third mathematical model aimed to determine the
average annual lifetime post-treatment medical costs for people treated with
the 3D regimen at varying stages of liver disease, again using the same
clinical trial population (abstract P0816).
A Markov model of the natural history of HCV was
developed based on previous models. Monetary values were based on a systematic
literature review of US costs of hepatitis C management. All direct medical
expenses were included in the model except for the cost of treatment (drugs,
viral load and side-effects monitoring, and management of adverse events).
People who started treatment before they developed
fibrosis (stage F0) had an annual average medical cost of US$297, which
gradually increased for those treated at stage F1 (US$416), stage F2 (US$563)
and stage F3 (US$760). But the cost rose dramatically, to US$3187, for people
who were not treated until they developed cirrhosis – more than tenfold
greater than the cost of treating at stage F0. Starting treatment at later
fibrosis stages resulted in increased average lifetime cost, even as life years
decreased.
"Our model suggests that genotype 1 HCV patients
who are treated with 3D +/- ribavirin earlier in the disease process incur
lower average annual lifetime medical costs compared to patients treated with
3D +/- ribavirin later in the disease process," they concluded.
"Consistent with existing literature, annual medical costs were much
higher for patients in stage F4 compared to earlier fibrosis stages."
Finally, Johnson's team developed a model to determine
the cost-effectiveness of 3D treatment compared to no treatment at different
fibrosis stages, using the same patient population (abstract P0815).
Unlike the previous model, this one also included the
cost of the drugs and expenses related to adverse events. For drug prices, they
used US$922 per day for the 3D regimen and US$14 per day for ribavirin.
Estimated adverse event costs ranged from US$318 for skin rash to US$1221 for
anaemia to US$2414 for thrombocytopenia (low platelets).
Total costs came out to US$82,783 for treatment plus US$10,445
for other direct medical costs for people treated with the 3D regimen, compared
to US$42,636 in direct medical costs for untreated patients.
The model showed that 3D with or without ribavirin was
cost-effective compared to no treatment for patients at any fibrosis stage and
with any treatment history, with an overall cost of US$16,978 per QALY. Even
when looking just at people who had not yet developed fibrosis (F0), treatment
was cost-effective at US$37,230 per QALY.
These findings
support the growing consensus among medical providers that all people with
chronic hepatitis C – regardless of current disease stage – should be eligible
for treatment, and that early treatment can be cost-effective.