• Treating hepatitis C: Introduction and background

    The following is the first in a series of guest posts by Allan Joseph, a medical student at the Warren Alpert Medical School of Brown University and TIE research assistant. You can follow Allan on Twitter: @allanmjoseph

    Austin recently drew our attention to one facet of the controversy over pricing a new drug named Sovaldi (generic name sofosbuvir, which is what I’ll use), produced by Gilead Sciences to treat chronic hepatitis C (HCV). We thought the subject warranted a deeper dive, which I’ll provide in this and several subsequent posts. (I’ll link to those posts right here, once they’re live.)

    1. Introduction and background [this post]
    2. Treatment options before 2014
    3. Sofosbuvir
    4. Criticisms of sofosbuvir
    5. Insurance coverage
    6. Policy solutions
    7. A literature update [posted on 4/16/15]

    Background

    Chronic HCV infection is a major public-health concern. At least 3 million Americans have HCV, which has a higher mortality rate than HIV. It’s even a bigger problem on a global scale, with estimates of up to 150 million chronic HCV infections worldwide.

    One of the clinical problems with HCV infection is the way the disease progresses. The majority of patients never have any symptoms when they’re first infected, and about 20% of those who contract the virus fight it off themselves. For the 80% who have chronic disease, the outcomes can vary widely. Over 20 years, about 10-20% of chronic cases progress to end-stage liver disease; roughly 20% of chronic cases can result in liver cirrhosis, and up to 5% of cases in liver cancer. (The ranges are large because of how many patients are unaware of their HCV infection.) It’s easiest to think of the chronic liver on a spectrum of “fibrosis,” which is essentially scar tissue replacing functional liver tissue — the more advanced the fibrosis, the more advanced the disease. Cirrhosis is the end of the spectrum; a cirrhotic liver has been taken over by scarring.

    That poses two challenges: first, essentially all patients who have HCV infection have no symptoms for decades, and second, a significant proportion of those with chronic HCV infections will never have symptoms of HCV infection in their lifetime. Yet we don’t have ways to predict that well, so we have to treat everyone, which is a big population.

    There are six different genotypes of the virus, which lead to different prognoses, and in some cases, different treatment regimens. Without getting into unnecessary details, let’s go over the three most common. Genotype 1 (GT1) is the most common (roughly 75% of infections), and it’s one of the more difficult types to treat. Genotypes 2 and 3 (GT2 and GT3) each account for about 10% of HCV infections, and they’re generally considered “easier” infections to treat. Remember that — it’ll come in handy later.

    There’s some (justified) debate over whether HCV can truly be “cured,” so we’ll use the “Sustained Virologic Response” (SVR) as our proxy — it’s the closest thing to a cure we’ve got, and it’s the outcome every study uses. It’s one of many terms that may be unfamiliar to readers, so I’ve included a glossary of terms and abbreviations below:

    Sustained Virologic Response (SVR): the absence of HCV genes in the patient’s blood 24 weeks after stopping treatment. It’s the proxy measurement for “cure,” which is a slippery term to begin with — a true “cure” could only be called after decades of follow-up.

    Efficacy: how well a drug or treatment works under idealized conditions (such as a clinical trial)

    Effectiveness: how well a drug or treatment works in the real world

    Cost-saving: interventions whose long-term pecuniary savings on a net present value basis exceed their costs on that same basis. Or, in simpler terms, treatments that pay for themselves due to lower, future costs (e.g., health care costs, but could be broader).

    Cost-effective: interventions judged to have greater benefits than harms — these may or may not be cost-saving. For example, neonatal intensive care units are almost certainly not cost-saving, but they’re cost-effective.

    Fibrosis: formation of scar tissue in the liver due to damage. Scar tissue tends to replace functional tissue, and the more advanced the fibrosis, the more advanced the disease.

    Cirrhosis: the most advanced form of fibrosis, where the liver is so scarred that it is essentially non-functional.

    @allanmjoseph

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