Erenumab Reduces Migraine Drug Utilization but Adherence Challenges Remain for Migraine Prophylaxis

An analysis of patient characteristics, adherence, and treatment patterns among US adult migraineurs prescribed erenumab revealed almost all individuals had prior use of acute or preventive therapies. Following initiation of erenumab, there was an observed decrease in use of acute and preventive prescription medications following initiation of erenumab—suggesting effectiveness in the real-world setting.

Adherence to erenumab was higher than that reported with traditional oral prophylactic migraine therapies. However, researchers noted that adherence rates for all migraine therapies were lower than desired.

Erenumab, a monoclonal antibody, is administered monthly via self-injection of a 70- or 140-mg dose and was first approved in 2018. The treatment blocks the calcitonin gene-related peptide (CGRP) receptor, which is believed to play a crucial role in migraine.

Although erenumab’s efficacy and safety have been established in placebo-controlled trails, little data is available on the treatment’s real-world use. To help address this knowledge gap, investigators used open-source pharmacy and medical claims databases to assess the treatment’s real-world use within the first year of its market availability in the United States.

Specifically, the retrospective cohort study included deidentified data from IQVIA’s LRx (pharmacy) and Dx (medical) claims databases. Individuals aged 18 or older with 1 or more prescriptions filled for erenumab between May 2018 and April 2019 were identified for inclusion.

“Patients were followed from their index date until discontinuation of erenumab, the end of their data stream, or the end of the study period; whichever occurred first,” authors wrote. A 12-month pre-index period and minimum 6-month follow-up period were also included in the study window.

Researchers assessed adherence by calculating proportion of days covered (PDC) and medication possession ratio (MPR). “PDC was measured as the number of days covered by erenumab divided by the number of days in the follow-up period,” while “MPR was measured as the total sum of days’ supply (where one dose was imputed as 30 days’ supply) divided by the number of days in the follow-up period.”

Of the 64,174 patients who met the study criteria, mean (SD) age was 48 (13) years while the majority (85.2%) were female. A total of 41,790 individuals received an initial erenumab dose of 70 mg and 81.4% of these patients maintained their index dose during follow-up.

Analyses revealed:

• 30.8% (n = 19,797) of patients had a PDC ≥ 0.80 and 41.7% (n = 26,769) had a MPR ≥ 0.80
• Discontinuation rates of acute and other prophylactic migraine therapies after initiation of erenumab (among users of the respective therapies) were 48.7% (22,965/47,190) and 36.1% (16,602/46,006), respectively
• Dose decreases among triptan, ergot compound, opioid, and barbiturate users were observed after initiation of erenumab
• Neurologists were the most common prescribers followed by nurse practitioners/physicians’ assistants and primary care providers

In the 12 months prior to starting erenumab, nearly one-quarter of migraineurs reported comorbid diagnoses including chronic pain, sleep disorders, depression, generalized anxiety disorder and osteoarthritis.

During the study window, researchers found that patients whose erenumab was covered by a commercial payer had higher rates of second and third refills compared with those with a discount/coupon or Medicare/Medicaid/cash payers. Adherence was lowest for those who accessed the treatment through a discount/coupon program and highest among patients with commercial coverage.

In a separate analysis of an adequate trial cohort (patients with 2 or more claims for erenumab within 80 days following the index claim [n = 29,451]), data indicated higher adherence rates than those in the overall population, “driven in part by the requirement that patients in this cohort had at least 3 months of treatment,” researchers explained.

As diagnoses are not available in the pharmacy claims database, researchers assumed erenumab prescriptions were made for treatment of migraine and cannot confirm utilization patterns observed were specifically related to migraine, marking limitations to the study. Consumption of therapy also was not confirmed.

“While exploration of adherence in an adequate trial population (patients with at least 3 months of continuous therapy) showed higher adherence, methods to improve adherence and the factors related to nonadherence merit additional inquiry,” authors said.

“Additional real-world studies that include experienced erenumab users, within an insurance coverage environment that is more established and longer follow-up periods are warranted,” they concluded.

Reference:

Hines DM, Shah S, Multani JK, et al. Erenumab patient characteristics, medication adherence, and treatment patterns in the United States. Headache. Published online February 16, 2021. doi:10.1111/head.14068