(361) Distribution and cost of common CF prescription drugs using claims data

Background: The IBM® MarketScan® Commercial Databases contain individual-level, de-identified, healthcare claims information from employers, health plans, and hospitals for a sample of privately insured individuals in the United States (US). Claims data has not been widely studied in Cystic Fibrosis (CF). We characterized the prescription drug elements of this dataset to evaluate opportunities to use pharmacy claims as a marker for adherence and to summarize out-of-pocket cost burden. Study aims were to 1) characterize frequency of pharmacy claims, 2) describe out-of-pocket cost of CFTR modulator prescriptions and 3) describe cost for other common CF medications.

Methods: We obtained a sample of IBM® MarketScan® data for individuals with at least one ICD-9 or ICD-10 code related to CF from 2010-2020. We reviewed CF specific pharmacy claims in this period to identify patients who have filled a prescription for any modulator medication. We also looked at of out-of-pocket cost for other commonly prescribed CF medications including dornase alfa, inhaled tobramycin, and inhaled aztreonam. We quantified total treatment supply by days for each medication to compare costs by frequency of claims.

Results: There were 3,065 individuals with over 55,000 claims for modulator therapy (62% adult and 48% female). Individuals could have claims for multiple modulators; there were 2,204 individuals (72%) with claims for a single modulator and 861 (28%) had claims for two or more different modulators. There were 783 (26%) with a claim for ivacaftor (Iva), 1,427 (47%) with lumacaftor/ivacaftor (Lum/Iva), 812 (26%) with tezacaftor/ivacaftor (Tez/Iva), and 1,170 (38%) with elexacaftor/tezacaftor/ivacaftor (ETI). Among individuals with ≥6 months of treatment supply, median (IQR) out-of-pocket annual cost was $384 (72, 720) for Iva, $367 (47, 750) for Lum/Iva, $300 (0, 646) for Tez/Iva, and $469 (50, 900) for ETI. The median (IQR) treatment supply within a year was 254 days (140, 336) for Iva, 168 (84, 308) for Lum/Iva, 196 (112, 280) for Tez/Iva, and 168 (56, 336) for ETI.

There were 9,777 individuals with over 190,000 claims for one or more claims of dornase alfa (49% female), tobramycin (48% female), or aztreonam (53% female). There was variation in age of claim for each treatment with; 48% of dornase alfa claims, 60% of tobramycin claims, and 76% of aztreonam claims being in adults. Among individuals with ≥6 months of treatment supply, median (IQR) annual out-of-pocket cost was: $204 (50, 401) for dornase alfa; $100 (0, 250) for tobramycin and $210 (0, 450) for aztreonam. The median (IQR) treatment supply within a year was: 120 days (60, 180) for dornase alfa; 56 days (28, 112) for tobramycin and 56 days (28, 85) for aztreonam.

Conclusions: This is the first summary of out-of-pocket drug costs for privately insured individuals with CF for commonly prescribed medications. Despite having private insurance, it appears that many people with CF do not fill their CF specialty medications at the suggested interval, it is unclear if this due to out of pocket cost or other factors. We found variation in cost of treatment, frequency of claims, and quantity of supply suggesting claims data may be a useful proxy for adherence and summarizing burden of care. Further work will explore the relationship between variation of cost of treatment and quantity of supply to define measures of adherence.

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