Pregnancy Briefly Lowers MS Relapse Rates and Treatment Reliance, Real-world Study Shows

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by Santiago Gisler |

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pregnancy and MS

Relapse rates in women with multiple sclerosis (MS) decline during pregnancy, as does the use of disease-modifying therapies, before both adjust to pre-pregnancy levels again, a large U.S. study based on real-world data shows.

The study, “Relapses and disease-modifying drug treatment in pregnancy and live birth in US women with MS,” was published in the journal Neurology.

One-fifth to one-third of women are thought to become pregnant and give birth after an MS diagnosis. Yet, little is known about the disease burden or treatment approaches directly before, during, and after pregnancy.

To better understand this in real-world populations, researchers used administrative U.S. data claims — healthcare data collected for billing and administration — for what the described as  is the first North American claims-based study investigating MS relapse and disease-modifying therapy (MDT) use in pregnancy.

Researchers at Harvard Medical School and EMD Serono gathered this data on 2,158 MS patients (mean age, 30.3) between 2006 and 2015, all with a confirmed diagnosis prior to childbirth, and available claims data spanning from one year before and one year after pregnancy.

The team analyzed MS relapse rates and treatment rates before, during, and after pregnancy. (Most relapses were so-called outpatient relapses, meaning patients were treated in a hospital for a relapse but not hospitalized.)

In general, data showed that relapse rates were lower during pregnancy compared to the year before pregnancy. Yet, after delivery, relapse rates increased and reached higher levels than before pregnancy, spiking at puerperium, which is the six-week period after delivery, before again dropping  “to similar rates observed in the prepregnancy period,” the study noted.

Pharmacy and medical claims one year before pregnancy through one year after delivery were used to assess DMT use by these patients.

Although disease-modifying treatment use was low in general (about 20% of the women pre-pregnancy), researchers found its decreased significantly during pregnancy compared with the period before pregnancy (1.9% versus 20%). DMT use continued to remain relatively low through puerperium (about 8.3%), before increasing again (25.5% at 9-12 months postpartum).

Based on the results, the team concluded: “the rate of MS relapse decreased during pregnancy, increased 6 months postpartum, and decreased 6 to 12 months postpartum. DMD treatment was uncommon in the year before pregnancy, further decreased immediately prepregnancy and during pregnancy, and increased postpartum.”

Researchers noted that, because they relied on claims data, their work likely fails to fully represent minority and poorer MS populations in the U.S. who rely on public health coverage, among other groups. Still, they said their  “findings are consistent with previous studies outside of North America evaluating relapse rates in women with MS during pregnancy.”

They added, “the size and relative ease of analysis with this retrospective administrative database, despite its limitations, affords us a great tool for understanding ‘real-world’ outcomes and opportunities for improving patient care,” and suggested that further such studies be conducted to explore patterns in clinical practice and pediatric outcomes in this patient population.

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