(A) Primary Hydroxychloroquine Adherence in Lupus Pregnancy

Publication Number: 291

Background: Many treatment adherence measures use pharmacy databases or claims using fill and refill interval data. Solely relying on fill data to measure adherence may result in equating perceived underutilization to patient non-adherence, and consequently ignores potential under-prescribing practices or other system challenges. For example, poor adherence has been reported for hydroxychloroquine (HCQ) use in lupus pregnancy based on fill data – often interpreting no fills as evidence of non-adherence, while failing to consider what was ordered.

Objectives: The main objective of this work is to demonstrate how incorporating medication order data, in combination with fill data, informs important discussions of adherence. Using both data sources, we quantified measured primary medication non-adherence in a cohort of lupus pregnancies.

Methods: In a retrospective cohort of 419 pregnancies of patients with lupus from a large integrated healthcare system, we used data on new medication orders and corresponding fill data for HCQ (2011-2020). New orders included past and never users. We calculated the proportion of new orders filled (and filled within 30 days) during pregnancy. For pregnancies with no new order, we identified those with refills that extended into pregnancy. We stratified by calendar year: 2011-2015, 2016-2019, and 2020 separately to account for COVID-19-related HCQ shortages.

Results: The overwhelming majority of patients filled their HCQ orders during pregnancy, most within 30 days of the order. Nearly 46% of pregnancies had a new order for HCQ and 93.2% were filled (83.3% filled 30d). In 2011-2015, 92.3% of new orders were filled (88.5% 30d), in 2016-2019 96.6% were filled (80.9% 30d), and fewer in 2020 (84.0% ever, 76.0% 30d). A considerable proportion of pregnancies without new orders for HCQ had refills before pregnancy that extended into pregnancy. During 2011-2015, 53% of pregnancies either had a new order or refill from a previous period, compared to 63.2% of 2016-2019 pregnancies, and 68.6% in 2020.

Conclusions: Published studies of HCQ use and adherence in lupus pregnancy have repeatedly found low proportions of patients with filled prescriptions for HCQ (often < 40%). Given that HCQ is almost universally indicated for managing SLE pregnancy, this low proportion is often interpreted as low patient adherence, without accounting for whether a prescription was ordered. By incorporating order information, our study shows that the overwhelming majority of patients (>90%) fill new orders for HCQ at least once.