The HERO (Hepatitis C Real Options) study found that self-reported compliance with direct-acting antiviral (DAA) therapy for HCV treatment in persons who inject drugs (PWID) frequently exceeds adherence levels measured objectively. The study found that self-reported adherence to DAA therapy was notably higher than objectively measured adherence by an average of 19.2% among PWID. A threshold of more than 25% overreported adherence optimally predicted reduced sustained virologic response (SVR) rates. Identifying PWID at risk of significant overreporting may be crucial for implementing more targeted interventions to enhance adherence.

Average adherence rates were 95.1% (SD = 8.9) for self-reported, 75.9% (SD = 16.3) for objective, and a 19.2% (SD = 15.2) disparity between the 2. The threshold for overreporting was optimally set at more than 25%. SVR rates were significantly lower in the group with more than 25% overreporting compared to those with less than 25% overreporting (86.7% vs. 95.8%, p < .001). Factors linked to more than 25% discrepancy in adherence included unemployment, a higher frequency of drug injection, more positive drug screens for amphetamine, methamphetamine, and oxycodone, and fewer positive screens for THC (tetrahydrocannabinol)/cannabis.

“The findings of our study are consistent with some prior studies that measured objective adherence with electronic blister packs among PWID and studies that measured objective adherence using medication event monitoring system (MEMS) caps and pill counts among the general population treated for chronic HCV where self-reported adherence overestimated actual adherence,” according to the investigators. “Our estimate of 19.2% difference between the self-reported and the objective measures is comparable to the difference of approximately 17% estimated in a prior study.”

The study analyzed data from 493 participants examining self-reported and objectively measured adherence to a 12-week course of DAA treatment. Adherence levels were assessed using visual analogue scales, for self-reported adherence, and electronic blister packs, for objective adherence. The difference between these 2 measures was calculated. An optimal threshold for overreporting that predicts lower SVR rates was established. Baseline characteristics were compared to identify factors associated with exceeding this threshold, by analyzing differences between participants who met or exceeded the threshold and those who did not.

“This is one of the first studies to focus on investigating how varying levels of discrepancy between self-reported and objective adherence measures relates to SVR,” according to the investigators. “While overreporting adherence is common, we have determined a threshold of overreporting that is predictive of significantly worse chances of achieving SVR; the validity of this threshold for predicting SVR should be tested further in future studies. By exploring the correlates of problematic levels of overreported adherence with respect to achieving the SVR outcome, our study also helps define the subpopulation of PWID with HCV who may benefit from additional adherence support.”

The study has several limitations, including its lack of generalizability due to population-specific factors and challenges of self-reported data, such as recall and social desirability biases. Methodological variations in adherence measurement across studies complicate direct comparisons, with this study employing electronic blister packs while others use different methods, affecting adherence rates and perceived discrepancies. The difficulty in identifying low actual adherence among individuals who report high levels of adherence. Additionally, the sample’s demographic composition, with low representation of women, minority groups, and rural populations, and small sample sizes for certain adherence categories.

All in all, healthcare providers might have to offer intensive support to PWID prone to overreporting to enhance adherence and increase the chances of SVR, directed towards issues like employment and facilitating connections to substance use treatments.

Reference

1. Lopes S, Pericot-Valverde I, Lum P, Taylor L, Mehta S, et. Al. Overreporting of Adherence to Hepatitis C Direct-Acting Antiviral Therapy and Sustained Virologic Response Among People Who Inject Drugs in the HERO Study. BMC Infectious Diseases. Published February 23, 2024. Accessed February 27, 2024. https://doi.org/10.1186/s12879-024-09124-3