COPENHAGEN — , even after accounting for treatment discontinuations during pregnancy and the postpartum period, new research suggested.
“We believe that pregnancy-related considerations probably still explain the major part of this gap,” said Antoine Gavoille, MD, University of Lyon, France, who presented the study at the 2024 ECTRIMS annual meeting.
This is likely due to “factors such as anticipation of pregnancy long before it occurs and fear of exposing women of childbearing age to certain treatments even in the absence of planned pregnancy,” he added.
Caution is warranted when medications are first marketed because there are no data on safety in pregnancy. However, in 2024, “this lesser treatment in women is unacceptable,” said Dr. Gavoille. “We now have several highly effective treatment options which are compatible with pregnancy,” he noted.
The researchers analyzed the French MS registry of 22,657 patients with relapsing MS (74.2% women) between 1997 and 2022 for treatment differences between women and their male counterparts. The results were adjusted for multiple factors including educational level, disease activity, disability levels, and discontinuation of drugs during pregnancy.
They found that over a median follow-up of 11.6 years, women had a significantly lower probability of receiving any disease-modifying treatment (odds ratio [OR], 0.92; 95% CI, 0.87-0.97).
In addition, women were even less likely to receive high-efficacy treatments such as natalizumab, anti-CD20 antibodies, or S1P modulators such as fingolimod (OR, 0.80; 95% CI, 0.74-0.86).
The difference in disease-modifying treatment usage varied across different treatments and over time. Teriflunomide, fingolimod, and anti-CD20 therapies were significantly underused throughout their entire availability (OR, 0.87, 0.78, and 0.80, respectively).
Interferon and natalizumab were initially used less frequently in women, but the use of these medications equalized over time.
In contrast, glatiramer acetate and dimethyl fumarate were initially used equally between genders but eventually became more commonly prescribed to women (OR, 1.27 and 1.17, respectively).
The disparity in treatment emerged after 2 years of disease duration for disease-modifying treatments in general and as early as 1 year for highly effective treatments.
The gender-based treatment gap did not significantly vary with patient age, indicating that therapeutic inertia may persist regardless of a woman’s age.
“Women may not be receiving the most effective therapies at the optimal time, often due to concerns about pregnancy risks that may never materialize,” said the study’s lead investigator Sandra Vukusic, MD, Lyon University Hospital, France.
“The main impact of this therapeutic inertia in women is the less effective control of disease activity, leading to the accumulation of lesions and an increased risk of long-term disability. This represents a real loss of opportunity for women, especially in an era where disease-modifying treatments so effective when used early,” she added.
Dr. Gavoille said that recommendations in France allow the use of moderately active drugs, including interferon and glatiramer acetate, during pregnancy or in women planning a pregnancy. More recently there has been enough data to allow the use of natalizumab up until the second trimester.
In addition, although not in the guidelines, it is thought that the anti-CD20 monoclonal antibodies, such as rituximab or ocrelizumab, may be safe as they are very long acting. Women can be dosed before pregnancy and be covered for the whole pregnancy period without exposing the fetus to the drug, he explained.
“The message is that now we have both moderately and highly effective treatments that are compatible with a pregnancy plan,” Dr. Gavoille said.
First, clinicians have to select a level of treatment based on disease activity and then choose the best option, depending on the woman’s plans with respect to pregnancy.
Drugs that are contraindicated in pregnancy include teriflunomide and S1P modulators such as fingolimod, which have been shown to be harmful to the fetus.
“But they could still be used in women of childbearing years as long as they are not planning a pregnancy and understand the need for contraception,” Dr. Gavoille noted.
He believes both neurologists and patients are afraid of using drugs in pregnancy. “It is, of course, important to be cautious on this issue, but we should not let fear stop these women receiving the best treatments available.”
However, he added, clinical practice is changing, and confidence is gradually building around using highly effective treatments in women of childbearing age.
Dr. Gavoille also called for more research to collate data in pregnant women with MS who are exposed to various treatments, starting with case reports and then academic registries, which he described as “difficult but important work.”
Commenting on the study, Robert Hoepner, MD, University Hospital of Bern, Switzerland, agreed that this treatment disparity between men and women is “unacceptable.”
Dr. Hoepner noted that a recent study showed that women have different relapse symptoms than men, which may also affect treatment choice.
Dr. Gavoille responded that other research has shown that women are less likely to have treatment escalation post-relapse. “This could be because of a difference in symptoms. But this is something we haven’t looked at yet.”
Also commenting on the research, Frauke Zipp, MD, University Medical Center Mainz in Germany, said it would be interesting to follow this cohort over the long term to see if the women do less well several years down the line.
The study authors and commentators reported no relevant disclosures.
A version of this article first appeared on Medscape.com.