1Meritxell Sabidó Espin, 2Kiliana Suzart-Woischnik, 3Nydjie Grimes, 4Lisa M Prach, 5Liwei Zhao, 5Katja M Hakkarainen
1Merck Healthcare KGaA, Darmstadt, Germany; 2Bayer AG, Berlin, Germany; 3Biogen Netherlands B.V., Badhoevedorp, Netherlands; 4Novartis Pharma AG, Basel, Switzerland; 5Global Database Studies (GloDaSt), Gothenburg, Sweden
Previous studies showed no increased risk of interferon beta use before or early in pregnancy among women with multiple sclerosis (MS). However, knowledge about the utilisation and safety of interferon beta in later-stage pregnancy remains limited. This study aims to determine (1) the number of pregnancies in women with MS exposed to interferon beta in later-stage pregnancy (i.e. the second and third trimesters) in Finland and Sweden; (2) whether the number of pregnancies available in Finland and Sweden is adequate for a cohort study to assess the outcomes of interferon beta exposure in later-stage pregnancy.
Material(s) and Method(s):
This observational drug utilisation study, using national register data in Finland (1996–2022) and Sweden (2005–2022), will report the number of pregnancies in women with MS (1) exposed to interferon beta only in later-stage pregnancy and (2) unexposed to any MS disease-modifying drugs. The 95% confidence intervals (Cls) of detectable relative risks (RR) for pre-defined adverse pregnancy outcomes are calculated for study size simulation. Based on the available background prevalence among the unexposed (Pbackground) and assuming 4% of all pregnancies are exposed, 100 exposed pregnancies are expected to be sufficient to detect all anomalies, spontaneous abortions, elective terminations (RR=2.00 [95%CI 1.40–2.89]; Pbackground 12.0%); preterm birth (RR=2.00 [95%CI 1.28–3.18]; Pbackground 8.3%); low birth weight (RR=2.00, [95%CI 1.03–4.05]; Pbackground 4.0%); major congenital anomalies (RR=2.50, [95%CI 1.32–4.92]; Pbackground 3.5%); and small for gestational age (RR=2.50 [95%CI 1.08-6.29]; Pbackground 2.0%).
One hundred exposed later-stage pregnancies are considered the minimum number for a cohort study on the adverse pregnancy outcomes. First results of this drug utilisation study will be reported in 2024. In case of inadequate number of pregnancies, the drug utilisation study will be extended for 2 years.
This drug utilisation study (EUPAS38736) will evaluate whether the accrued number of exposed pregnancies is adequate for a cohort study to evaluate the safety of interferon beta exposure in later-stage pregnancy among women with MS.