User:Mdomin27/Multiple sclerosis

Epidemiology
MS is the most common autoimmune disorder of the central nervous system. As of 2020, the estimated number of people with MS was 2.8 million globally, with a prevalence of 36 per 100,000 people. Moreover, prevalence varies widely in different regions around the world. In Africa, there are 5 people per 100,000 diagnosed with MS, compared to South East Asia where the prevalence is 9 per 100,000, 112 per 100,000 in the Americas, and 133 per 100,000 in Europe.

According to the National MS Society, a study conducted in 2017 estimated that there are nearly one million people living with multiple sclerosis in the United States. Increasing rates of MS may be explained by various factors such as improved methods of diagnosis and increased number and availability of treatments. Studies on population and geographical patterns have been common and have led to a number of theories about the cause, though the cause of MS continues to be unclear.

MS usually appears in adults in their late twenties or early thirties, though in rare cases can start in childhood or after 50 years of age. The primary progressive subtype is more common in people in their fifties. Similarly to many autoimmune disorders, the disease is more common in women, and the trend may be increasing. As of 2008, globally it is about two times more common in women than in men. In children, it is even more common in females than males, while in people over fifty, it affects males and females almost equally.

Management
Main article: Management of multiple sclerosis

Although no cure for multiple sclerosis has been found, several therapies have proven helpful. Several effective treatments can significantly decrease the number of attacks and the rate of progression. The primary aims of therapy are returning function after an attack, preventing new attacks, and preventing disability. Starting medications is generally recommended in people after the first attack when more than two lesions are seen on MRI.

The first approved medications used to treat MS were modestly effective, though were poorly tolerated and had many adverse effects. Several treatment options with better safety and tolerability profiles have been introduced, improving the prognosis of MS.

As with any medical treatment, medications used in the management of MS have several adverse effects. Alternative treatments are pursued by some people, despite the shortage of supporting evidence of efficacy.

Initial management of acute flare
During symptomatic attacks, administration of high doses of intravenous corticosteroids, such as methylprednisolone, is the usual therapy, with oral corticosteroids seeming to have a similar efficacy and safety profile. Although effective in the short term for relieving symptoms, corticosteroid treatments do not appear to have a significant impact on long-term recovery. The long-term benefit is unclear in optic neuritis as of 2020. The consequences of severe attacks that do not respond to corticosteroids might be treatable by plasmapheresis.

Relapsing remitting multiple sclerosis
Multiple disease-modifying medications were approved by regulatory agencies for RRMS; they are modestly effective at decreasing the number of attacks. The interferons and glatiramer acetate are first-line treatments and are roughly equivalent, reducing relapses by approximately 30%. Early-initiated long-term therapy is safe and improves outcomes.

Treatment of CIS with interferons decreases the chance of progressing to clinical MS. Efficacy of interferons and glatiramer acetate in children has been estimated to be roughly equivalent to that of adults. The role of some newer agents such as fingolimod, teriflunomide, and dimethyl fumarate, is not yet entirely clear. Making firm conclusions about the best treatment is difficult, especially regarding the long‐term benefit and safety of early treatment, given the lack of studies directly comparing disease-modifying therapies or long-term monitoring of patient outcomes.

The relative effectiveness of different treatments is unclear, as most have only been compared to placebo or a small number of other therapies. Direct comparisons of interferons and glatiramer acetate indicate similar effects or only small differences in effects on relapse rate, disease progression, and MRI measures. Alemtuzumab, natalizumab, and fingolimod may be more effective than other drugs in reducing relapses over the short term in people with RRMS. Natalizumab and interferon beta-1a (Rebif) may reduce relapses compared to both placebo and interferon beta-1a (Avonex) while Interferon beta-1b (Betaseron), glatiramer acetate, and mitoxantrone may also prevent relapses. Evidence on relative effectiveness in reducing disability progression is unclear. All medications are associated with adverse effects that may influence their risk to benefit profiles.

Ublituximab was approved for medical use in the United States in December 2022.

Progressive multiple sclerosis
In 2011, mitoxantrone was the first medication for secondary progressive MS. In this population tentative evidence supports mitoxantrone moderately slowing the progression of the disease and decreasing rates of relapses over two years.

In March 2017, the FDA approved ocrelizumab as a treatment for primary progressive MS in adults, the first drug to gain that approval, with requirements for several Phase IV clinical trials. It is also used for the treatment of relapsing forms of multiple sclerosis, to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease in adults.

New approved medications continue to emerge in modern medicine. In 2019, siponimod and cladribine were approved in the United States for the treatment of secondary progressive multiple sclerosis (SPMS). Subsequently, ozanimod was approved in 2020 and ponesimod was approved in 2021, which were both approved for management of CIS, relapsing MS, and SPMS in the U.S., and RRMS in Europe.