Receiving a 90-day supply of tenofovir disoproxil fumarate (TDF) or entecavir versus a 30-day supply was linked to better adherence among commercially insured adults with chronic hepatitis B, according to study findings published in Open Forum Infectious Diseases.

Antiviral therapy can keep hepatitis B virus replication suppressed, but it usually does not lead to a cure, so long-term treatment is necessary. People who do not take antivirals consistently face poor outcomes, including viral load rebound and hepatitis flare-ups.

Jonathan Alpern, MD, of the Minneapolis Veterans Affairs Health Care System, and colleagues analyzed risk factors for nonadherence to antiviral therapy among people with chronic hepatitis B.

Using the Merative MarketScan Commercial Database, they accessed claims data for commercially insured adults with were prescribed either entecavir (Baraclude or generic equivalents) or TDF (Viread or generic equivalents) in 2019. The analysis included 770 people who only received entecavir and 852 who only received TDF.

Participants who filled prescriptions to cover at least 80% of days were considered adherent. About 90% received generic rather than brand-name medications. The average out-of-pocket spending for a 30-day supply was higher for entecavir ($73) than for TDF ($44). People who received 90-day prescriptions were more like to use mail-order pharmacies.

Overall, adherence levels were similar for the two groups: 83% of those on entecavir and 81% of those on TDF were deemed adherent. Among people prescribed entecavir, those given a 90-day supply more likely to be adherent than those given a 30-day supply (90% versus 77%). In addition, those who used a mail-order pharmacy had a higher adherence rate than those who did not. Adherence was similar regardless of out-of-pocket and insurance payments.

Among people prescribed TDF, those given a 90-day supply again achieved better adherence than those who received a 30-day supply (89% versus 74%). Those with a high-deductible health plan also showed better adherence. Further, people who paid more than $25 out of pocket for a 30-day supply of TDF had a lower rate of adherence than those who paid less than $5.

“These findings suggest that longer duration of prescribed supplies of entecavir and TDF may improve medication adherence for patients with chronic hepatitis B requiring long-term therapy and should be prioritized by clinicians,” the study authors wrote. “Longer-duration supplies have the advantage of requiring fewer trips to the pharmacy and less frequent refills, thus theoretically reducing the risk of late refills.”

Nonetheless, more people in this study received 30-day supplies than 90-day supplies of entecavir or TDF. Possible reasons include health plan restrictions on the duration of prescriptions and clinician behavior. Longer-duration supplies, the researchers suggested, “would be an important step to improve adherence among vulnerable, high-risk populations with chronic hepatitis B.”

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