A link between hormonal contraception and MS?

A study scheduled to be presented at the American Academy of Neurology’s 66th annual meeting in April suggests a possible connection between use of hormonal contraception and risk of multiple sclerosis (MS).

Researchers conducted a population-based nested case-control study, “Hormonal Contraceptives and Multiple Sclerosis Susceptibility,” using data from members of Kaiser Permanente Southern California (KPSC). They identified females aged 14-48 years who had MS or its precursor (clinically isolated syndrome [CIS]) between 2008 and 2011.

Ten controls per case were matched on age, race/ethnicity, and membership characteristics. Data were obtained from the complete electronic health record and analyzed using conditional logistic regression, adjusted for smoking and live births 3 years prior to symptom onset.

The authors identified 305 women with MS/CIS and 3050 matched-controls. Hormonal contraception was used for at least 3 months within the 3 years prior to symptom onset by 29.2% of cases and 23.5% of controls. The majority used estrogen/progestin combination pills. Risk of MS/CIS was increased slightly in women who used any hormonal contraceptive in the 3 years prior to symptoms onset, particularly those who had stopped at least 1 month prior to symptom onset (ever-users adjusted OR = 1.35, 95% CI = 1.01-1.80, P = 0.04; not current users adjusted OR = 1.50, 95%CI =1.05-2.14, P = 0.026).

In the abstract for the meeting, the researchers write that their findings suggest that use of modern hormonal contraception may be contributing, at least in part, to the rise in incidence of MS in women. Additional analysis will be presented at the meeting in a question-and-answer session on risk factors for MS.