As Out-of-Pocket Costs Rise, Drug Adherence Falls in Rheumatoid Arthritis

The cost of disease-modifying antirheumatic drugs for rheumatoid arthritis remains a concern.

Patients who have higher member out-of-pocket (OOP) costs are less likely to initiate or refill a biologic disease-modifying antirheumatic drug (DMARD) therapy for rheumatoid arthritis (RA), a recent study found.

For the study, published in the Journal of Managed Care & Specialty Pharmacy, researchers identified members of Humana, a national Medicare Advantage and Prescription Drug (MAPD) plan, with an adjudicated claim — either paid or reversed – for a biologic DMARD for RA from July 1, 2007 to December 31, 2012.

Two distinct populations were analyzed in the study, with the first being used to assess prescription drug abandonment rates, while the date of the initial claim was considered the index date.

Members were required to have 180 days of continuous enrollment pre- and post-index and ≥ 1 diagnosis for RA (ICD-9-CM: 714.0 or 714.2) during pre-index or ≤ 30 days post-index.

Patients in the low income subsidy and with Medicaid and Medicare dual eligibility were excluded.

A preliminary univariate trend test was calculated to determine if the OOP cost was associated with the likelihood of abandoning a prescription for a biologic DMARD. Researchers then used multivariate logistic regression models to test for an association between OOP cost and the rate of prescription abandonment.

Initially, 8442 patients were eligible for the study, but this number dropped down to 4777 because of the lack of continuous enrollment in a health plan, 180 days before and after the index date. The population dropped again to 3209 after participants were excluded for age and lack of a medical claim for RA.

After all exclusions, the final sample size included 864 MAPD members with an adjudicated claim for a biologic DMARD. The majority of participants were female (77.4%) with a mean age of 63.5 years (SD=10.9).

More than half of study participants lived in urban areas and most had conventional nonbiologic DMARD utilization during pre-index (78%).

Overall, there was an initial abandonment rate of 18.2%, ranging from 1.3% for the lowest OOP cost group ($0-$250) to 32.7% for the highest OOP cost group (> $550; P < 0.0001 for Cochran-Armitage trend test).

Researchers observed that the rate of prescription abandonment increased when the OOP cost increased. The overall abandonment rate increased from 18.4 to 32.7 to 41.2 for OOP costs of $250.01-$400.00, $400.01-$550.00, and > $550.00, respectively, relative to OOP costs of ≤ $250.00 (all P < 0.0001).

Meeting the catastrophic coverage limit and the utilization of a specialty pharmacy for the index claim were both associated with a decreased likelihood of abandoning therapy (OR = 0.29 and OR = 0.14, respectively; both P < 0.05).

The negative association between OOP cost and the likelihood of refilling a prescription was highly significant (P < 0.0001), the study found. Among the subset of the 533 members with a paid claim, 82.4% were reported to have had at least 1 refill post-index.

The study concluded that there is an unmet need for affordable biologic DMARDs. The higher the OOP cost, the less likely it is for an MAPD member to follow through with refilling a biologic DMARD prescription.

If these issues are addressed by reducing OOP costs, it could help increase adherence among RA Medicare members. However, further research needs to be done to better understand the reasons for initial prescription abandonment and the lack of medication refills, including benefit design and adverse events.