OIG finds only 23% of Medicaid patients with hepatitis C were treated within 6 months of testing

On November 2, 2026, the HHS Office of Inspector General posted a data brief titled *Less Than 25 Percent of Medicaid Beneficiaries With Hepatitis C Received Treatment Within 6 Months* (OEI-BL-24-00450, issued October 28). OIG used 2023 and 2024 Medicaid and Medicare claims to see how many Medicaid beneficiaries with hepatitis C started one of the curative oral drugs within 6 months of testing.

The answer was fewer than one in four. For a coding desk, the more useful part of the report is how OIG decided who had hepatitis C in the first place: it relied on the diagnosis codes on claims, and it says plainly that it didn't check whether those codes were right.

What OIG found in the Medicaid hepatitis C data brief

OIG identified about 230,000 Medicaid beneficiaries with hepatitis C in 2023. Only 23 percent of them received treatment within 6 months of testing through Medicaid, or through Medicare for beneficiaries who were dual-eligible.

Among beneficiaries who were treated within 6 months, the median time from test to treatment was 49 days. One-third started within 30 days, and one-quarter waited more than 90 days. Forty-one percent of the beneficiaries treated within 6 months got their first prescription from a primary care provider, and 33 percent got it from gastroenterology, hepatology or infectious disease specialists.

OIG points out that clinical and public health guidance recommends immediate treatment for nearly all patients, whatever the stage of the disease. During the review period, the drugs weren't explicitly FDA-approved for acute infection, which OIG says may have held down treatment for that group. A widely used hepatitis C drug received that expanded indication in June 2025.

How OIG used diagnosis codes to build the study population

OIG didn't have test results, so it worked from claims alone. A beneficiary counted as having hepatitis C if a 2023 claim included a hepatitis C test (screening, antibody, RNA or genotype testing) and a claim within the next 180 days carried an ICD-10-CM code for acute, chronic or unspecified hepatitis C. OIG then left out people who had been treated in the 6 months before the test, children under 3, and people without full-scope Medicaid benefits.

In its limitations section, OIG says it didn't review medical records or test results and didn't verify whether providers assigned hepatitis C diagnosis codes correctly. Its example is one coders will recognize: a provider assigns a hepatitis C code after a positive antibody test, without waiting for the confirmatory RNA test. OIG says that kind of misclassification may artificially reduce the measured treatment rate.

The ICD-10-CM codes for hepatitis C

The FY 2027 ICD-10-CM code descriptions file splits hepatitis C into acute, chronic and unspecified codes, the same three groups OIG searched for. You can look each one up in the Code Book. The right column shows how each code maps in CMS's 2027 initial ICD-10-CM mappings for the CMS-HCC V28 model, which you can also check in the ICD-10 to HCC lookup.

In the V28 model software, HCC 64 (Cirrhosis of Liver) sits above HCC 65 in the hierarchy, so when both are present, HCC 64 is the one that counts. The table isn't a reason to pick one code over another. The code has to match what the provider documents. It does show why the difference between "chronic," "acute" and an unqualified "hepatitis C" in the note matters for Medicare Advantage risk adjustment as well as for studies like this one.

What the outpatient guidelines say about an unconfirmed result

OIG's example lines up with Section IV.H of the FY 2027 ICD-10-CM Official Guidelines for Coding and Reporting. In outpatient settings, coders don't code diagnoses documented as "probable," "suspected," "questionable," "rule out," "compatible with," "consistent with," or "working diagnosis." Instead, they code to the highest degree of certainty for that visit, such as symptoms, signs or abnormal test results. Under that rule, a reactive antibody test that the provider documents as suspected or not yet confirmed is coded as the abnormal result, not as hepatitis C.

Section IV.J covers the other end of the timeline. Coders don't report conditions that were treated and no longer exist. When a cured infection still affects current care, a personal history code from subcategory Z86.1- (personal history of infectious and parasitic diseases) can be reported as a secondary code. If the provider's note doesn't make clear whether the infection is active, chronic or resolved, that's a question for the provider. Our MEAT criteria guide is a quick way to check whether the note supports a current condition.

What CMS agreed to do

OIG made two recommendations, and CMS concurred with both:

• Raise hepatitis C treatment rates in Medicaid. CMS says it will build on its work with states and support reporting on a new voluntary hepatitis B and C measure in the 2027 Medicaid Adult Core Set. In its comments, CMS says the measure looks at adult Medicaid beneficiaries who aren't dual-eligible and counts those tested for hepatitis B, tested for hepatitis C and treated for hepatitis C. Reporting on the 2027 Adult Core Set, for services provided mostly during 2026, takes place in fall 2027.
• Take targeted steps for dual-eligible beneficiaries. Because Medicare is generally the primary payer for people enrolled in both programs, OIG says CMS may be better positioned than state Medicaid programs to find and address the barriers. CMS says it will review existing data and work with partners on options. OIG also suggests CMS look at treatment rates across all Medicare beneficiaries, since this study covered only those who were dual-eligible.

For more on hepatitis C coverage, see our earlier report on CMS's reconsideration of the HCV screening NCD.