Persistence on therapy and propensity matched outcome comparison of two subcutaneous interferon beta 1a dosages for multiple sclerosis.

• Main Authors: Tomas Kalincik, Timothy Spelman, Maria Trojano, Pierre Duquette, Guillermo Izquierdo, Pierre Grammond, Alessandra Lugaresi, Raymond Hupperts, Edgardo Cristiano, Vincent Van Pesch, Francois Grand'maison, Daniele La Spitaleri, Maria Edite Rio, Sholmo Flechter, Celia Oreja-Guevara, Giorgio Giuliani, Aldo Savino, Maria Pia Amato, Thor Petersen, Ricardo Fernandez-Bolanos, Roberto Bergamaschi, Gerardo Iuliano, Cavit Boz, Jeannette Lechner-Scott, Norma Deri, Orla Gray, Freek Verheul, Marcela Fiol, Michael Barnett, Erik van Munster, Vetere Santiago, Fraser Moore, Mark Slee, Maria Laura Saladino, Raed Alroughani, Cameron Shaw, Krisztian Kasa, Tatjana Petkovska-Boskova, Leontien den Braber-Moerland, Joab Chapman, Eli Skromne, Joseph Herbert, Dieter Poehlau, Merrilee Needham, Elizabeth Alejandra Bacile Bacile, Walter Oleschko Arruda, Mark Paine, Bhim Singhal, Steve Vucic, Jose Antonio Cabrera-Gomez, Helmut Butzkueven, MSBase Study Group
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2013-01-01
• Series: PLoS ONE
• Online Access: https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23704913/?tool=EBI

<h4>Objectives</h4>To compare treatment persistence between two dosages of interferon β-1a in a large observational multiple sclerosis registry and assess disease outcomes of first line MS treatment at these dosages using propensity scoring to adjust for baseline imbalance in disease characteristics.<h4>Methods</h4>Treatment discontinuations were evaluated in all patients within the MSBase registry who commenced interferon β-1a SC thrice weekly (n = 4678). Furthermore, we assessed 2-year clinical outcomes in 1220 patients treated with interferon β-1a in either dosage (22 µg or 44 µg) as their first disease modifying agent, matched on propensity score calculated from pre-treatment demographic and clinical variables. A subgroup analysis was performed on 456 matched patients who also had baseline MRI variables recorded.<h4>Results</h4>Overall, 4054 treatment discontinuations were recorded in 3059 patients. The patients receiving the lower interferon dosage were more likely to discontinue treatment than those with the higher dosage (25% vs. 20% annual probability of discontinuation, respectively). This was seen in discontinuations with reasons recorded as "lack of efficacy" (3.3% vs. 1.7%), "scheduled stop" (2.2% vs. 1.3%) or without the reason recorded (16.7% vs. 13.3% annual discontinuation rate, 22 µg vs. 44 µg dosage, respectively). Propensity score was determined by treating centre and disability (score without MRI parameters) or centre, sex and number of contrast-enhancing lesions (score including MRI parameters). No differences in clinical outcomes at two years (relapse rate, time relapse-free and disability) were observed between the matched patients treated with either of the interferon dosages.<h4>Conclusions</h4>Treatment discontinuations were more common in interferon β-1a 22 µg SC thrice weekly. However, 2-year clinical outcomes did not differ between patients receiving the different dosages, thus replicating in a registry dataset derived from "real-world" database the results of the pivotal randomised trial. Propensity score matching effectively minimised baseline covariate imbalance between two directly compared sub-populations from a large observational registry.