FormalPara Key Summary Points

This retrospective study utilized administrative claims data from a large United States population of patients who initiated erenumab (which was approved in May 2018 for the preventive treatment of migraine) between May 2018 and September 2019 with 12-month pre-index and post-index periods.

Most patients had prior use of acute and preventive therapies for migraine before starting erenumab.

Decreased use of acute and traditional migraine-preventive medications and small reductions or stability in the utilization of healthcare resources over a longer (12-month) post-index period were observed.

Overall, higher adherence to erenumab was associated with greater reductions in these measures.

The results from this study are consistent with previous reports employing a shorter post-index period (6 months).

Introduction

Migraine is a specific type of headache characterized by recurrent attacks of moderate to severe throbbing and pulsating pain, often accompanied by increased sensitivity to light, noise, and odors, nausea, and/or vomiting [1]. Migraine prevalence in the United States (US) was 16% in 2018 across all adults, with a higher prevalence in women (21%) compared with men (11%) [2]; global estimates are similar (14–15%) [3]. Migraine is a significant public health concern which contributed to approximately 4 million emergency room (ER) visits and 4.3 million office visits in the US in 2016, with migraine being the fifth most common reason for an ER visit overall and the third most common for females aged 15–64 years [2].

Calcitonin gene-related peptide (CGRP) is a neuropeptide that plays a pivotal role in the pathophysiology of migraine [4]. Erenumab (erenumab-aooe in the US), an anti-CGRP pathway monoclonal antibody (mAb), was the first of four migraine-specific preventive treatments approved by the US Food and Drug Administration (May 2018); the approval of other mAbs followed: fremanezumab-vfrm (September 2018), galcanezumab-gnlm (September 2018), and eptinezumab-jjmr (February 2020). Except for eptinezumab administered intravenously, anti-CGRP pathway mAbs are self-administered by subcutaneous injection. These medications have demonstrated their clinical efficacy in terms of reductions in monthly days with migraine, the use of acute medication for migraine, as well as positive impacts on functional and patient-related outcomes [4,5,6,7].

Before the availability of anti-CGRP pathway mAbs, medications that were indicated for other conditions (e.g., hypertension, depression, and epilepsy) but had a secondary effect on migraine were used for prevention. These agents, commonly referred to as traditional or non-specific migraine-preventive medications, continue to be used for the preventive treatment of migraine despite their limited efficacy, poor tolerability, and suboptimal outcomes for many patients [8, 9].

Real-world data (RWD) can provide valuable information on migraine prevention treatment patterns and how a treatment may translate into changes in healthcare resource utilization (HRU). A study using US claims data reported erenumab persistence in 47% of patients and a mean adherence of almost 70% [10]. While the use of acute and traditional migraine-preventive medications decreased, there was a minimal reduction in HRU and associated costs overall, a result that may be due to the limited 6-month follow-up period of the study. Another RWD study of US claims data for patients initiating any anti-CGRP pathway mAb (including erenumab, fremanezumab, and galcanezumab) found that 41% were persisting with the index medication at the 12-month follow-up, with a mean adherence of 55%; no HRU was reported [11].

Prior research using RWD has demonstrated reductions in HRU with the initiation of erenumab within a short time period of 6 months. Specifically, Tepper et al. found significant reductions in acute medication use and HRU within 6 months of initiating erenumab [12, 13]. In addition, Hines et al. reported the discontinuation of acute and other prophylactic migraine therapies following the initiation of erenumab [14]. The objectives of this study were to expand on prior work by describing longer-term (12-month) medication use patterns and changes in HRU and associated direct costs, overall and by level of adherence, among patients initiating erenumab.

Methods

Study Design and Data Source

This retrospective cohort study used data from the Merative™ MarketScan® Commercial and Medicare Databases to identify adult patients with migraine treated with erenumab from May 2018 through September 2019. The MarketScan Commercial Database contains the inpatient (IP) and outpatient (OP) medical and OP pharmacy experience of employees and their dependents, covered under a variety of fee-for-service and managed-care health plans. The MarketScan Medicare Database contains the healthcare experience of retirees with Medicare Advantage and Medicare Supplemental insurance plans paid for by employers. It includes the employer-paid portion and out-of-pocket patient expenses for both Advantage and Supplemental plans as well as the Medicare-covered portion of the payment (represented as the coordination of benefits amount) for Supplemental plans. Both the MarketScan Commercial and Medicare Databases contain adjudicated claims which provide detailed cost, use, and outcomes data for healthcare services for nearly 40 million enrollees during the patient selection window.

MarketScan databases are in compliance with the Health Information Portability and Accountability Act of 1996 (HIPAA). As this study did not involve the collection, use, or transmittal of individually identifiable data, it did not require institutional review board (IRB) approval.

Patient Selection and Cohort Assignment

Adult patients (≥ 18 years of age) with a pharmacy claim for erenumab between May 2018 and September 2019 were selected for the study. The date of first erenumab claim was considered the index date. Patients were required to have continuous medical and pharmacy coverage for at least 12 months before the index date (pre-index period) and 12 months after the index date (post-index period) and to have evidence of migraine in the pre-index period, defined as at least one medical claim with an International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis code for migraine (applicable G43.* codes are described in Supplementary Table 1) or at least one pharmacy or medical claim for acute migraine-specific medications (i.e., triptans or ergots). Patient selection based on these requirements is presented in Supplementary Fig. 1.

Outcomes

Demographic characteristics (age, sex) were measured on the index date. Comorbidities, migraine type, medications, and HRU were measured during both the pre- and post-index periods. Comorbidities (anxiety, asthma, constipation, depression, hypertension, and irritable bowel syndrome) and migraine type (migraine with aura [including or excluding persistent aura], chronic migraine, menstrual migraine, and status migrainosus) were identified using ICD-10-CM diagnosis codes on IP or OP medical claims. Migraine medications were captured using National Drug Code (NDC) codes on pharmacy claims and Healthcare Common Procedure Coding System (HCPCS) codes on medical claims (for office-administered medications) and included acute medications (i.e., triptans, ergots, nonsteroidal anti-inflammatory drugs [NSAIDs], opioids, other analgesics [acetaminophen, baclofen, butalbital, and ziconotide], gepants [ubrogepant and rimegepant], and lasmiditan) as well as traditional migraine-preventive medications (i.e., anti-convulsants, anti-depressants, anti-hypertensives, botulinum toxins [onabotulinumtoxinA, abobotulinumtoxinA injection, incobotulinumtoxinA injection, onabotulinumtoxinA injection, and rimabotulinumtoxinB injection], and other migraine preventives [carisoprodol, cyproheptadine, guanfacine, memantine, and milnacipran]). Healthcare resources included IP hospitalizations, ER visits, OP care visits, and brain- or other head-imaging services (captured using Current Procedure Terminology [CPT] or HCPCS). Costs associated with acute and traditional migraine-preventive medications and the healthcare resource categories listed above were reported as per patient per year during the 12-month pre- and post-index periods and summed across categories to report total costs excluding the cost of erenumab. Cost information was based on paid amounts of adjudicated claims, including insurer and health plan payments as well as patient cost sharing in the form of a copayment, a deductible, and coinsurance. Costs for services provided under capitated arrangements were estimated using payment proxies based on paid claims at the procedure level using the MarketScan Commercial and Medicare Databases. All dollar estimates were inflated to the most recent data year dollars (2019) using the medical care component of the Consumer Price Index.

Adherence to erenumab was assessed during the post-index period using the proportion of days covered (PDC). PDC was calculated as the number of days in the post-index period covered by erenumab divided by the total number of days in the post-index period (i.e., 12 months). The number of days covered was calculated as the sum of days’ supply for all erenumab prescription fills; overlapping days for early refills were appended (the start date was adjusted to be the day after the previous fill had ended), and days’ supply was truncated on the last day of the post-index period. In addition to reporting the mean and standard deviation (SD) PDC, patients were classified as adherent (PDC ≥ 80%) or non-adherent (PDC < 80%). Erenumab starting dose was captured as 70 or 140 mg on the index claim. Erenumab dose change (maintained, increased, or decreased) during the post-index period was reported according to the starting dose. Erenumab persistence was reported as the proportion of patients remaining on erenumab during the post-index period, with a 45-day gap after exhausting the days’ supply used to define discontinuation and with no switching to or addition of a non-erenumab anti-CGRP pathway mAb (including fremanezumab-vfrm, galcanezumab-gnlm, and eptinezumab-jjmr) required. A switch to or the addition of a non-erenumab anti-CGRP pathway mAb during the post-index period was captured and reported separately from persistence. The specialty of the prescribing physician for the index dose was derived from the most proximal claim with a migraine diagnosis (ICD-10-CM) or office-administered medication (HCPCS) specific for migraine treatments in the 90 days prior to the index date.

Statistical Analysis

All data were summarized using descriptive statistics overall and by erenumab adherence category. Categorical variables were presented as the count and percentage of patients in each category; continuous variables were summarized by providing the mean and standard deviation (SD). The change (difference) from pre- to post-index period was described overall and by PDC category (adherent/non-adherent).

Results

Sample Size, Demographics, and Baseline Characteristics

A total of 7528 patients met the eligibility criteria (Supplementary Fig. 1); of those, 2898 (38.5%) and 4630 (61.5%) comprised the cohorts of patients adherent (PDC ≥ 80%) and non-adherent to erenumab treatment, respectively. Mean (SD) age at first erenumab claim was 45.1 (11.4) years, and 85.4% of patients were female (Table 1). The most common pre-index comorbidities were anxiety (23.0%), depression (20.0%), hypertension (18.6%), and asthma (7.5%). The majority of patients had a diagnosis of chronic migraine (59.4%) during the pre-index period.

Table 1 Patient demographics and baseline clinical conditions
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Baseline Migraine Medication Use

Nearly all patients (95.6%) had prescription claims for acute migraine medications in the pre-index period; of these, 36.0% had claims for three or more types of acute medications (Supplementary Table 2). The most commonly used acute medications during the pre-index period were triptans (72.7%), NSAIDs (58.2%), and opioids (50.9%). Few patients had claims for ergots (4.4%) and, as expected based on the timing of FDA approval, none had claims for gepants/lasmiditan (0.0%). Pre-index-period mean costs for acute migraine medications were $1763 overall, with slightly lower costs for patients adherent to erenumab ($1607) compared to non-adherent patients ($1860).

Similarly, nearly all patients (89.6%) had prescription claims for traditional migraine-preventive medications in the pre-index period; among these, 32.2% had claims for three or more types of these medications. The most commonly used traditional migraine-preventive medications included anti-convulsants (56.6%) and anti-depressants (56.0%). Pre-index-period mean costs for traditional migraine-preventive medications were $2276 overall, with slightly lower costs for adherent ($2201) compared to non-adherent ($2323) patients.

Baseline HRU

Overall, there was minimal utilization of IP hospitalization (7.8%) in the pre-index period; however, almost all patients (99.8%) had at least one OP care visit, and over a third of patients (36.5%) had an ER visit (Supplementary Table 3). The pre-index mean cost of medical services per patient was over $13,000. Pre-index utilization of medical services was lower for adherent compared with non-adherent patients for ER visits (34.3% of adherent and 37.8% of non-adherent patients), IP hospitalizations (6.7% and 8.5%, respectively), and brain or other head imaging (26.8% and 29.0%, respectively). Aligned with this, the mean cost of medical services was lower among adherent patients ($12,811) compared with non-adherent patients ($13,719).

Erenumab Treatment Patterns

Overall, the mean (SD) PDC was 0.60 (0.32) (Supplementary Table 4). The majority (67.8%) of all patients started on the 70-mg dose of erenumab. Dose escalation during the post-index period from 70 to 140 mg occurred in 37.4% of all patients starting on 70 mg, with a higher proportion of adherent (50.0%) versus non-adherent (28.9%) patients undergoing a dose increase. Dose reduction from 140 to 70 mg occurred in 15.4% of all patients starting on 140 mg, with a higher proportion of adherent (19.7%) versus non-adherent (13.1%) patients reducing their dose. The proportion of patients switching to/adding non-erenumab anti-CGRP pathway mAbs (i.e., fremanezumab, galcanezumab, and eptinezumab) was 19.2% overall: 3.8% among adherent and 28.9% among non-adherent patients. Persistence on erenumab was 40.1% overall: 93.6% among adherent and 6.7% among non-adherent patients. Overall, the most common prescribing physician specialty was neurology (42.6%).

Changes in Comorbidities and Migraine Type

The proportion of patients with each comorbid condition remained stable between the pre- and post-index periods; the absolute difference between periods was no more than 2% (Supplementary Table 5). The proportion of patients with claims relating to migraine type decreased between the pre- and post-index periods. The change in the proportion of patients with each migraine type from the pre-index to the post-index period differed by level of adherence; it was most noticeable for chronic migraine, with reductions of 5.3% and 1.5% among the adherent and non-adherent subgroups, respectively.

Changes in Claims and Associated Cost for Migraine Medication Use

There was a reduction in the proportion of patients with claims for acute (Fig. 1) and traditional migraine-preventive (Fig. 2) medications post-erenumab initiation that was more pronounced in adherent patients. The largest change in the proportion of patients with acute medication claims was for triptans, with a 7.3% reduction (− 8.3% in adherent and − 6.6% in non-adherent patients), while the largest change for traditional migraine-preventive medication claims was for anti-convulsants, which had a 12.3% reduction (− 15.4% in adherent and − 10.4% in non-adherent patients).

Fig. 1
figure 1

Acute migraine medications: a pre-index, post-index, and change overall and b change by erenumab adherence

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Fig. 2
figure 2

Traditional migraine preventive medications, a pre-index, post-index, and change overall and b change by erenumab adherence

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Reductions in medication claims resulted in decreases in acute, traditional migraine-preventive, and total medication costs, which were more pronounced in adherent compared to non-adherent patients (Fig. 3). Acute migraine medication costs decreased by $293 from the pre- to the post-index period, and traditional migraine-preventive medication costs decreased by $471. The reductions were nearly the same for adherent and non-adherent patients for acute medication costs (− $297 and − $290, respectively) but greater for adherent compared to non-adherent patients for traditional migraine-preventive medication costs (− $568 and − $411, respectively). The mean total per patient cost of acute and traditional migraine-preventive medications was $4039 in the pre-index period and $3275 in the post-index period, a reduction of $764. Reductions observed among adherent patients (− $864) were greater than those among non-adherent patients (− $701).

Fig. 3
figure 3

Migraine medication costs: a pre-index, post-index, and change overall and b change by erenumab adherence

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Changes in HRU and associated cost

There were reductions in the proportions of patients requiring ER visits and brain/head-imaging studies (− 3.8% and − 7.5%, respectively) post-erenumab initiation, with more-pronounced reductions among adherent patients (Fig. 4). The use of OP care visits and IP hospitalizations remained relatively stable overall and by level of adherence. Similarly, the mean number of visits/services per 100 patients decreased overall from the pre-index to the post-index period, with a more-pronounced reduction seen among adherent patients for ER visits and OP office visits (Supplementary Fig. 2).

Fig. 4
figure 4

HRU by service category: a pre-index, post-index, and change overall and b change by erenumab adherence. ER emergency room, IP inpatient, OP outpatient

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Reductions in claims for ER visits and brain/head-imaging studies post-erenumab initiation resulted in modest reductions in mean costs for these services overall (− $167 and − $143, respectively; Fig. 5). The pre- to post-index change in costs by adherence level revealed greater reductions for all services in adherent versus non-adherent patients. While there was a small increase in total medical service costs post-erenumab initiation overall ($76), the pre- to post-index change in costs for adherent versus non-adherent patients translated into an overall reduction in medical services costs among adherent patients (− $1083) and a cost increase for non-adherent patients ($802).

Fig. 5
figure 5

Costs by service category: a pre-index, post-index, and change overall and b change by erenumab adherence. ER emergency room, IP inpatient, OP outpatient

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Combining both medication (acute and traditional migraine-preventative therapies) and medical costs, the total cost reduction post-erenumab initiation was $688 (Fig. 6). For adherent patients, there was a cost reduction of nearly $2000. For non-adherent patients, there was a $101 cost increase.

Fig. 6
figure 6

Medication and medical costs: a pre-index, post-index, and change overall and b change by erenumab adherence

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Discussion

This study demonstrated the continued real-world clinical benefits of erenumab over 12 months of follow-up among a large US patient population. Results from this study showed a decrease from the pre-index to the post-index period in acute and traditional migraine-preventive medication use as well as in ER visits and brain/head-imaging studies, with more-pronounced reductions among patients who were adherent versus those who were non-adherent to erenumab. Notably, these reductions in utilization resulted in a total cost decrease of nearly two thousand dollars per patient for adherent patients over the year of follow-up, reflecting reductions in both acute and traditional preventive-migraine medication costs (− $864) and associated medical utilization (− $1083).

Results from this study are generally consistent with other real-world analyses of patients initiating erenumab. The erenumab patient profile was similar to those in published studies, including a mean age between 44 and 51 years and a majority who were female (79–92%) [4]. The change in migraine type prevalence observed in this study is consistent with results observed in the Chandler et al. study, which also used MarketScan data but with a 6-month follow-up [10].

The reduction in acute migraine medication utilization after erenumab initiation observed in this study is well documented in the literature. Using Optum’s combined electronic health record and claims database, Tepper and colleagues observed significant reductions in migraine-specific acute medication use and HRU in the 6 months after erenumab initiation: a significant decrease in migraine-specific office visits from 86.2% to 77.6% and a decrease in claims for health care utilization of 10–19% [12, 13]. Hines and colleagues used IQVIA’s open-source claims database to report the discontinuation or reduced consumption of acute migraine-specific medication in the 6 months following erenumab initiation; among those patients with pre- and post-medication use, 36.8% discontinued their acute migraine-specific medication, based on there being no refills for ≥ 60 days [14]. Less information exists about the change in traditional migraine-preventive medication usage after erenumab initiation. Chandler et al. demonstrated a reduction in preventive medication use during the 6-month pre- to post-index period: the use of preventive medication (which included non-erenumab anti-CGRP pathway mAbs) changed from 87.3% in the pre-index period to 80.2% in the post-index period [10].

In this study, the proportion of patients using each specific acute and traditional migraine-preventive medication class decreased from the pre-index to the post-index period (e.g., triptan use decreased from 72.7% to 65.4% and anti-convulsants from 56.6% to 44.3%). Of note, this study included data through September 2020, allowing for the capture of newly approved medications (gepants/lasmiditan) in the post-index period that were not readily available during the pre-index period due to the relative timing of FDA approval.

While a reduction in migraine-preventive medication was observed from the pre-index to the post-index period, the use of traditional migraine-preventive medication was not replaced completely with the initiation of erenumab (e.g., 44.3% used anti-convulsants, 50.9% used anti-depressants, and 33.2% used anti-hypertensives in the post-index period). The literature supports the use of combination therapy in migraine prevention, potentially leading to better outcomes and lower dosages [15]. Approximately 40% of patients do not significantly benefit from monotherapy for migraine prevention, so using multiple agents from at least two different preventive medication classes may be beneficial [16]. In a retrospective analysis of medical charts from five US headache centers, chronic migraine patients treated with erenumab continued to be managed via a polypharmacy approach despite the demonstrated effectiveness of erenumab [17]. Finally, many of the traditional preventative medications are indicated not just for migraine but for other conditions (e.g., depression and hypertension), which can also contribute to their continued use. Particularly in this analysis using claims data, the indication (e.g., migraine versus depression) cannot be confirmed. But utilizing medications that result in positive benefits for coexisting conditions may be beneficial.

Despite the introduction of gepants and lasmiditan in the post-index period, the total medication cost (for acute and traditional migraine-preventive medications) decreased from the pre-index to the post-index period by $764. The medication cost reduction was nearly $900 for erenumab-adherent patients. The additional 6 months of follow-up in this study confirm the trends observed in Chandler et al.; total associated costs for healthcare resources among adherent patients were $770 lower during the 6-month follow-up period compared to the corresponding pre-index timeframe in Chandler et al. and $1083 lower during the 12-month follow-up period compared to the corresponding pre-index timeframe in this study [10]. A recent publication by Tepper et al. using US claims data from the Komodo Health database included erenumab costs and demonstrated an initial entrance cost associated with erenumab via an increase in migraine-related prescription costs during the 6-month pre- to post-index period; however, this was offset by reduced migraine-related medical costs and lower odds of migraine-related ER, office, and neurologist visits [18].

It is noted that differences in associated non-medication costs appear to be driven by small differences in the mean number of services. For example, the difference in ER visits per 100 patients was a reduction of 9.6 overall (− 18.5 in adherent and − 4.1 in non-adherent patients), and the difference in costs was a reduction of $167 overall (− $260 in adherent and − $109 in non-adherent patients). But for OP office visits, while the number of visits decreased among non-adherent patients (− 49.1 per 100 patients), an increase in OP visit costs of $816 ($9320 pre-index vs $10,136 post-index) was observed, suggesting that non-adherent patient visits were more intensive and therefore more costly.

This study measured persistence with and adherence to erenumab, with the results stratified by adherence and non-adherence. At 12 months, the reported persistence in this study was 40.1%, based on a 45-day gap. In Chandler et al., the reported persistence at 3 and 6 months following erenumab initiation was 72.6% and 47.3%, respectively, based on the same 45-day gap [10]. Mean PDC was 0.68 in the 6-month follow-up period in Chandler et al., compared to the value of 0.60 observed during the 12-month follow-up period in this study [10]. However, the 38.5% adherence over the 12-month post-index period in this study is higher than the 30.8% adherence measured over the 6-month post-index period using IQVIA’s open-source claims database [19].

The adherence to and persistence with erenumab reported in this study as well as others are higher than those for medications traditionally used for migraine prevention [20, 21]. A study using MarketScan data to compare anti-CGRP pathway mAbs (including erenumab, fremanezumab, and galcanezumab) to traditional migraine-preventive medications showed that 32.7% were adherent to anti-CGRP pathway mAbs, compared to 18.7% who were adherent to medications considered the standard of care in a 12-month follow-up [11].

This study was not intended as an economic analysis, so associated costs of anti-CGRP pathway mAbs were not included. Rather, the costs of acute or traditional migraine-preventive medications and the associated HRU were included as an indicator of the impact of erenumab that accounts for both changes in the proportion of patients utilizing and the extent of that utilization. Economic analyses of cost-effectiveness, clinical effectiveness, and value-based price for erenumab in the US have been previously published [22,23,24].

The results from this study highlight the impact of adherence to erenumab on associated medication and healthcare resource cost savings in the post-index period. Patients who were adherent to erenumab had an overall cost reduction (− $1947), whereas non-adherent patients had a cost increase ($101). Future studies may consider capturing both indirect costs from negative impacts on work productivity as well as direct costs, as this can provide a more complete story of the significant burden of migraine [24, 25]. For example, a Finnish study reported a 73.9% decrease in headache-related sick leave days in the 12 months following erenumab treatment among a cohort of employed patients with migraine [26].

Limitations

The limitations of this study include those inherent in any retrospective claims-based analysis. This study was limited to medical claims from US-centric databases. Results of this analysis may not be generalizable to migraine patients overall or to other countries. The potential for misclassification of migraine status, covariates, or study outcomes was present, as patients were identified through administrative claims data as opposed to medical records. Claims data lack information on the frequency or severity of migraine attacks and do not distinguish among migraine subtypes (while there is an ICD-10-CM code for chronic migraine [G43.7*], there is no similar code for episodic migraine). A potential imbalance in healthcare resource utilization by migraine severity may result in less-precise cost estimates. As with any claims databases, the MarketScan Research Databases rely on administrative claims data for clinical detail. These data are subject to data-coding limitations and data entry error. Medication use was based on filled prescriptions. Patients were assumed to take the medications as prescribed, but whether patients actually took the medications cannot be confirmed. The intended indication for the traditional migraine-preventive medications prescribed cannot be established, whether they were intended for migraine, another condition, or both, and whether they were used acutely or on a regular schedule, such as daily use. Patients with discontinuation due to a change in insurance drug coverage of erenumab may confound the assessment of adherence. Outpatient pharmacy claims do not include the diagnosis or prescribing physician information; therefore, the prescribing physician was approximated based on proximal ICD-10-CM or HCPCS medical claims. Because this study aimed to quantify the changes in utilization and direct cost associated with acute and traditional migraine-preventive medications when initiating erenumab, the associated cost of anti-CGRP pathway mAbs was not included. Therefore, reductions in cost reported here are specifically within the context of the medication categories reported and do not represent cost decreases related to overall migraine medication use. Finally, there may be systematic differences between the adherent and non-adherent cohorts that account for differences found in healthcare costs and utilization.

Conclusions

In this study of a large US population of patients who initiated erenumab, most patients had prior use of acute and preventive therapies for migraine before starting erenumab. The results from this study are consistent with those previous that employed a shorter follow-up period. This study observed reductions in claims for migraine types, a shift to decreased use of acute and traditional migraine-preventive medications, and small reductions or stability in the utilization of healthcare resources over a longer (12-month) follow-up period. Overall, higher adherence to erenumab was associated with greater reductions of these measures. These observations provide additional evidence indicative of the clinical benefits of erenumab in the real-world setting.