Viral Hepatitis: Hepatitis C

0:00Welcome to Board Pearls. This is episode three of three of the Viral Hepatitis chapter, in the Liver Disease module. This episode is hepatitis C: the reflex antibody-then-RNA diagnosis, the pangenotypic direct-acting antiviral regimens by fibrosis stage and renal function, the special populations including decompensated cirrhosis and kidney disease, and the post-cure cancer surveillance question.

0:26Start from the orienting fact that organizes everything: chronic hepatitis C is now a curable disease, the most consequential development in hepatology in the past decade, and it pulls the whole workflow toward the same end, identify the virus, confirm replication, stage the liver, pick the regimen, document cure, then ask the one remaining question about long-term cancer risk. The mechanism behind cure is direct-acting antivirals targeting the nonstructural viral proteins needed for replication and assembly, in three classes: the protease inhibitors, whose names end in "previr," the NS5A inhibitors, ending in "asvir," and the polymerase inhibitors, ending in "buvir," with sofosbuvir the key nucleotide, and the combination regimens hit two targets at once. The cure rate across genotypes is over ninety-five percent, with relapse beyond twelve weeks after treatment very rare, and that's what cure looks like in this disease.

1:23The diagnostic question lives in two tests in a fixed order: the hepatitis C antibody first, then the RNA as a reflex when the antibody is positive. The antibody establishes past infection, the RNA establishes current infection, and both are required because the antibody persists for life after exposure regardless of whether the infection cleared, so the antibody alone can't distinguish active from resolved infection. The interpretation is small enough to own as reflex: antibody positive with RNA positive is infection, acute or chronic, and triggers treatment; antibody positive with RNA negative is resolved infection or a false-positive antibody, since a substantial minority of acute infections clear spontaneously, more often in symptomatic illness, in women, and in younger patients; and antibody negative with RNA positive is rare, meaning a false-positive RNA, an early acute infection before the antibody has caught up, or hepatitis C in an immunosuppressed host who never mounted an antibody. The first trap is the same one flagged in episode one: the antibody becomes positive only a couple of months after infection, so a high-suspicion patient with a negative antibody isn't cleared, and the RNA is what closes the question, so a stem with an injection drug user, a recent high-risk exposure, and an acute hepatitis picture with a negative antibody doesn't stop there, the next move is the RNA, and documented seroconversion during the illness proves acute hepatitis C. Universal screening covers all adults at least once, with annual testing added in people who inject drugs and other high-risk groups, and it replaced birth-cohort-only screening because incidence has shifted toward young adults driven by the injection drug epidemic, so the principle is simple: if incidence is broad, screening is broad.

3:04Once diagnosed, the pre-treatment workup is a short checklist with internal logic: a chemistry and blood count for baseline, HIV testing because coinfection changes drug interactions, hepatitis B serology because reactivation during antiviral therapy in surface-antigen-positive patients has occurred and carries a warning, a baseline viral load, fibrosis assessment by elastography or the noninvasive scores, and a pregnancy test because ribavirin is teratogenic when added. Genotype testing has become optional in the pangenotypic era, reserved for treatment-experienced or special situations, and the hepatitis B serology is the easiest item to forget and the one the boards love most.

3:30That sets up the treatment decision, taught by mechanism first, regimen second. The two preferred first-line regimens are both pangenotypic, both combinations of two drug classes, and both for treatment-naive patients with or without compensated cirrhosis. The sofosbuvir-velpatasvir combination, a polymerase inhibitor plus an NS5A inhibitor, is twelve weeks, covers all genotypes, and extends into decompensated cirrhosis with ribavirin added, which we'll come back to. The glecaprevir-pibrentasvir combination, a protease inhibitor plus an NS5A inhibitor, is eight weeks and pangenotypic for treatment-naive patients with or without compensated cirrhosis, and that eight-week duration even in treatment-naive compensated cirrhosis is the current rule the boards now test, since older teaching extended the duration in cirrhosis but the current rule keeps it at eight weeks as long as the cirrhosis is compensated and the patient is treatment-naive, with the duration extending only in selected treatment-experienced or prior-failure scenarios. The salvage regimen adds a third drug, a protease inhibitor, to the sofosbuvir-velpatasvir backbone for twelve weeks, reserved for prior NS5A failures and sofosbuvir-regimen failures, so you don't reach for it as initial therapy even in compensated cirrhosis, it's the rescue drug. Older genotype-specific combinations still exist for niches but aren't first-line, so the teaching version is the two pangenotypic regimens plus the one salvage regimen and everything else is footnote. Treatment is recommended for all patients with chronic hepatitis C regardless of fibrosis stage, the only exception being a short life expectancy that cure can't remediate, and mild fibrosis, active substance use, and even ongoing injection drug use don't defer treatment, because the public-health and individual arguments run the same direction.

5:19A few practical pearls travel with the regimens. The first is the sustained-virologic-response language: it means undetectable RNA twelve weeks after the end of treatment, not twelve weeks of treatment, and that's the trap, because stems that describe twelve weeks of drug and call it cure are using the wrong endpoint, since it's the post-treatment measurement that represents durable cure. The second is what cure buys beyond virology: fibrosis regresses in many cirrhotics, cancer incidence in patients who already had cirrhosis drops substantially though not to baseline, which is the entire premise of post-cure surveillance, mortality falls, the liver scores improve modestly in decompensated patients, and the extra-hepatic manifestations resolve, so mixed cryoglobulinemia improves, hepatitis-C-associated lymphoma can remit with cure alone, and the porphyria, glomerulonephritis, lichen planus, and elevated diabetes and cardiovascular rates all decline, which means the rheumatology, renal, and dermatology consults often need cure first, not immunosuppression first. The third is that acute hepatitis C is treated promptly with a full-duration regimen, the same drugs and durations as chronic infection, because waiting for spontaneous clearance trades cures for chronic disease.

6:36The rest of the chapter is the special-populations set, built on a small number of fixed rules, and the first organizes everything else: protease inhibitors are unsafe in decompensated cirrhosis, because they accumulate in hepatic impairment and have been associated with severe decompensation in Child-Pugh B and C cirrhosis, carrying a boxed warning, and that rule is absolute, so a stem with ascites, low albumin, hyperbilirubinemia, or a prior variceal bleed fitting Child B or C is one where the protease-inhibitor-containing regimens are wrong answers. The preferred regimen in decompensated cirrhosis is sofosbuvir-velpatasvir for twelve weeks with weight-based ribavirin when feasible, since the ribavirin combination gives the highest response, or sofosbuvir-velpatasvir without ribavirin extended to twenty-four weeks when ribavirin is contraindicated by anemia or renal or pregnancy concerns, so the binary is twelve weeks with ribavirin or twenty-four weeks without. The practical wrinkle attached is the MELD-improvement problem: patients with decompensated cirrhosis who clear the virus often improve enough that their score falls, but not enough to feel well, so they lose priority on the transplant list while remaining symptomatic, and the decision rule has two halves, offer treatment before transplant when the MELD is roughly fifteen to eighteen or below with preserved albumin, and defer until after transplant when the MELD is higher, because pre-transplant cure in a sicker patient may reduce transplant access without restoring quality of life, and the patient should be counseled about the trade-off.

8:04The second rule is about kidneys, and the data have shifted: sofosbuvir was historically restricted in advanced renal impairment, but that restriction is gone, and it's now used in advanced kidney disease including dialysis, so sofosbuvir-velpatasvir is acceptable there when needed, while glecaprevir-pibrentasvir has no nucleotide and is directly renally safe, remaining the favored choice in advanced kidney disease or dialysis when liver function is preserved. So the general rule is that decompensated cirrhosis forbids protease inhibitors and renal impairment no longer forbids sofosbuvir, making the dominant choice in kidney disease without decompensation the glecaprevir-pibrentasvir regimen. The third rule is transplant: post-transplant treatment achieves cure rates similar to pre-transplant, using the standard pangenotypic regimens for twelve weeks, with decompensated allograft cirrhosis following the same rules as a decompensated native liver, and the drug-interaction map mattering because the transplant medication list is long, so tacrolimus is generally easier than cyclosporine with protease-inhibitor regimens, amiodarone plus sofosbuvir produces symptomatic bradycardia and is avoided, and acid blockers alter the absorption of the pH-dependent NS5A drugs. The fourth rule is pregnancy: the antivirals aren't approved during gestation, so the recommendation is to treat before pregnancy when feasible or postpartum when the diagnosis is made on prenatal screening, which is universally recommended at the first prenatal visit, with vertical transmission at a modest rate that's higher with HIV coinfection, fetal-blood-exposure procedures like scalp electrodes avoided, and breastfeeding not a transmission risk. Some women clear the virus spontaneously postpartum, which is why the RNA is rechecked before postpartum treatment rather than assuming chronic infection, and ribavirin is teratogenic with a six-month washout applying to female patients and to female partners of male patients on it. Children of infected mothers are tested with the antibody at eighteen months or later, when maternal antibody has cleared, and with the RNA later to confirm chronicity.

10:01That brings us to the post-cure question, the highest-yield single point in the back half of the chapter: after cure, who continues cancer surveillance and who stops. The answer hinges on fibrosis stage at the time of cure, because cure doesn't eliminate the cancer risk in patients who already have cirrhosis, dropping the incidence substantially but leaving a rate still above the surveillance threshold. So surveillance continues every six months with ultrasound, with or without alpha-fetoprotein, indefinitely in patients with cirrhosis at cure, meaning F4 fibrosis, because the cancer risk never returns to baseline so the surveillance never stops. And the next level is explicit: surveillance is not recommended in patients with advanced bridging fibrosis without cirrhosis after clearance, so F3 is where the rule changes, because cure plus the absence of true cirrhosis drops the residual risk below where surveillance pays off. Hold that boundary precisely: F4 means continue surveillance forever, F3 without cirrhosis means stop after cure, the two tiers look adjacent on the scoring system but the surveillance decision flips between them, and that's the test point. Patients with milder fibrosis plus additional risk factors like ongoing alcohol, fatty liver, or persistent diabetes get repeat fibrosis assessment a few years post-cure to recalibrate, since the data on stopping are still maturing, so the rule is to reassess rather than discharge. One more pearl in the post-cure folder: the antiviral therapy itself does not increase cancer recurrence after curative resection or transplant, contrary to early signals, so the decision to treat after curative cancer therapy isn't constrained by that fear. And the last piece is reinfection: cure is durable as long as exposure stops, so a patient with prior cure who resumes high-risk exposure can be reinfected, which looks like new viremia in someone known to have cleared, and a genotype change supports reinfection over relapse, with retreatment using a pangenotypic regimen like any treatment-naive patient because the prior cure didn't produce resistance, and active substance use isn't a reason to defer.

12:01So pull it together. Hepatitis C is diagnosed in two tests, the antibody then the reflex RNA, the antibody establishing exposure and the RNA active infection, with the first trap being that the antibody lags viremia by a couple of months in acute infection, so the RNA confirms acute hepatitis C when the antibody is negative. Universal screening covers all adults at least once with annual testing in high-risk groups, and the pre-treatment workup includes hepatitis B serology because reactivation during therapy is the reason for it. Treatment uses two preferred pangenotypic regimens, sofosbuvir-velpatasvir for twelve weeks and glecaprevir-pibrentasvir for eight, including in treatment-naive compensated cirrhosis, with the three-drug salvage regimen for failures, and cure is the undetectable RNA twelve weeks after treatment ends. Special populations modify the regimen by two rules: decompensated cirrhosis forbids protease inhibitors, so the answer is sofosbuvir-velpatasvir with ribavirin for twelve weeks or without for twenty-four, and advanced kidney disease no longer forbids sofosbuvir but glecaprevir-pibrentasvir is the simplest choice when liver function is preserved. And post-cure, cancer surveillance continues indefinitely in patients with cirrhosis at cure while patients with advanced fibrosis short of cirrhosis stop after clearance, which is the single highest-yield post-cure question.

13:26The next chapter shifts from viral injury to drug injury and shared final pathways: drug-induced liver injury and acute liver failure, with amoxicillin-clavulanate the most commonly implicated single agent, metabolic activation turning innocuous drugs into hepatotoxins, Hy's Law as the severity-with-mortality threshold, N-acetylcysteine for acetaminophen, and the transplant-triage criteria that move a patient from supportive care to listing.

13:53For the full chapter, the practice vignettes, and the topic-tagged question bank, head to board pearls dot com. You'll find the rest of the series on Apple Podcasts, Spotify, or wherever you listen to podcasts. That brings us to the end of episode three of three of chapter eighteen, and I'll see you in the next one.