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. 2015 Nov;30(11):1633-8.
doi: 10.1007/s11606-015-3285-7. Epub 2015 Apr 9.

Reductions in Use of Colchicine After FDA Enforcement of Market Exclusivity in a Commercially Insured Population

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Reductions in Use of Colchicine After FDA Enforcement of Market Exclusivity in a Commercially Insured Population

Aaron S Kesselheim et al. J Gen Intern Med. .
Free PMC article

Abstract

Background: A brand-name version of colchicine (Colcrys) was introduced after its manufacturer conducted a clinical trial in acute gout patients, leading to higher prices for this drug.

Objective: We analyzed the impact of the new single-source colchicine product on prescribing and patient health spending as well as incidence rates of potentially dangerous concomitant use of clarithromycin and cyclosporine after formal FDA approval.

Design/participants: We conducted a retrospective cohort study of UnitedHealth-affiliated enrollees newly diagnosed with gout or FMF.

Main measures: Among gout and FMF patients separately, we assessed linear trends in colchicine prescriptions, prescription drug costs, and total health care costs from 2009 to September 2010 (market exclusivity announced) compared to January 2011 (market exclusivity enforced) through 2012. Next, we estimated trends in co-prescription within 15 days of clarithromycin, azithromycin (indicated on the Colcrys label for use in place of clarithromycin), and cyclosporine.

Key results: Among gout patients, before Colcrys' market exclusivity, the odds of receiving colchicine within 30 days of gout diagnosis increased 1.4 %/month (OR: 1.014, 95 % CI: 1.011-1.018). Following FDA action, the odds decreased by 0.5 %/month (OR: 0.995, 95 % CI: 0.992-0.999) (p < 0.001). Similarly, among FMF patients, odds of initiating colchicine changed from an increase of 2.8 %/month to a decrease by 7.6 %/month (p = 0.01). Patients receiving colchicine experienced increases in average monthly prescription drug costs ($418 vs. $651, p < 0.001) and health care costs ($3,406 vs. $3,534, p < 0.001). Incidence rates of colchicine/clarithromycin co-prescription before and after FDA action did not change, while co-prescription of colchicine/cyclosporine increased after introduction of Colcrys [-0.75 monthly change in patients (95 % CI: -1.07, -0.43) vs. 0.13 (95 % CI: -0.16, 0.42), p < 0.001].

Conclusions: The FDA's actions were associated with a reduction in colchicine initiation and an increase in patient spending. By contrast, we did not observe any association with improvements in avoidance of potentially dangerous co-prescriptions.

Figures

Figure 1
Figure 1
a Percent of newly diagnosed gout patients receiving colchicine, 2009–2012. b Percent of newly diagnosed FMF patients receiving colchicine, 2009–2012. Legend: This figure shows the raw percent of newly diagnosed gout (a) and FMF (b) patients initiating colchicine each month from January 2009–December 2012, along with the trends in initiation, as estimated from the discontinuity logistic regression model
Figure 2
Figure 2
Panel a Number of patients receiving concomitant prescriptions of colchicine and clarithromycin, adjusted for the overall use of each drug over time, 2009–2012. Panel b Analysis for concomitant prescriptions of colchicine and azithromycin, 2009–2012. c Analysis for concomitant prescriptions of colchicine and cyclosporine, 2009–2012. Legend: This figure shows the number of patients who received a concomitant prescription for clarithromycin (a), azithromycin (b), and cyclosporine (c) within 15 days of a colchicine prescription, adjusted for the background trends in use for each drug, along with the adjusted trends in concomitant use, as estimated from the discontinuity model. In the raw data, adjustment was carried out by standardizing the number of concomitant prescriptions observed each month based on the average number of prescriptions per month for each drug over the entire study period

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