Benefit restrictions and gout treatment

Gout is a chronic rheumatic disease that can have serious sequelae, including persistent pain, nerve compression, joint destruction and deformities if left untreated. Febuxostat, initially introduced in the United States in 2009, was the first new treatment option for gout in over 40 years. With the introduction of a new drug into a therapeutic class that is composed of generically available options, utilization management will be a common strategy employed in an effort to contain cost; however, the effects of these strategies are not known for chronic gout treatment.

To evaluate the effect of utilization management strategies on chronic gout treatment.

This retrospective analysis examined claims data from a large, national pharmacy benefits manager with a client base that includes commercial HMOs, Medicaid, Medicare Part D, and self-insurers. The study population included patients aged 18 years or older who had at least 1 rejected claim for febuxostat in the 16-month identification period from March 1, 2009, through June 30, 2010. Outcomes of interest were the proportion of patients who filled a febuxostat prescription and proportion of patients who filled a prescription for another chronic gout treatment within 1 month of the febuxostat claim rejection date (the index date). Multivariate logistic regression models were used to assess factors affecting patient response to a rejected febuxostat claim.

Of 1,034 patients with rejected febuxostat claims, 95% had claims denied due to utilization management: 36% due to step therapy, 25% due to lack of drug coverage, 18% due to quantity or other limits (i.e., fill limit exceeded, days supply exceeding benefit maximum, or maximum days supply limit exceeded), 16% due to prior authorization requirements, while 5% were due to "other reasons" unrelated to the utilization management strategies of interest. "Other reasons" included over 100 possible rejection reasons such as fill dispensed too soon, missing/invalid days supply, group not having benefit, physician not covered, non-matched group, not a network pharmacy, non-matched member, claim/member birth date not matching, and missing/invalid prescriber identifier. Subsequently, 474 (46%) of these patients filled a febuxostat prescription within 1 month of a rejected claim; 364 (35%) had not filled a prescription for any chronic gout medication within a month of the febuxostat claim rejection. Those filling a febuxostat prescription had higher pre-index total 6-month pharmacy costs than those not filling a chronic gout prescription ($1,718 vs. $988; P < 0.001) . They also had a higher number of pre-index drug claims (25 vs. 18; P < 0.001). The regression model found the following variables to be statistically significant in positively influencing the likelihood of patients filling a febuxostat prescription within a month of a febuxostat claim rejection: (a) self-insured coverage (compared with commercial HMO coverage); (b) pre-index total prescription costs of at least $1,800; (c) claim rejection due to quantity or other limit (compared with lack of drug coverage); (d) claim rejection due to "other reason" (compared with lack of drug coverage); and (e) 1 and ≥1 pre-index colchicine claim. Patients with projected febuxostat copay of $100 to $149 were found to be less likely to fill febuxostat compared with patients with a projected copay of $0 to $19.

Utilization management strategies likely result in gaps in gout treatment; 35% of patients with a denied febuxostat claim in this study population did not fill a prescription for any chronic gout therapy within a month of the claim denial. These findings are important in the consideration of benefit design in gout treatment.