Refractory MG Poses Burden to U.S. Healthcare System, Needs Better Treatments, Study Finds

People with myastenia gravis (MG) whose disease is refractory, or resistant, to conventional therapies, are more likely to have disease flare-ups, visit an emergency room, be hospitalized, or be admitted to an intensive care unit — using more healthcare resources — than patients with nonresistant MG, a U.S. study found.

The findings highlight the need for more effective treatments for this patient population — ones that will improve outcomes and quality of life, along with reducing the burden on the healthcare system.

The study, “Examining the Impact of Refractory Myasthenia Gravis on Healthcare Resource Utilization in the United States: Analysis of a Myasthenia Gravis Foundation of America Patient Registry Sample,” was published in the Journal of Clinical Neurology.

Recommended medications for MG include anti-acetylcholinesterase agents, corticosteroids such as prednisone, and steroid-sparing immunosuppressant therapies (ISTs).

While these treatments are effective against most or all of the disease symptoms in many patients, in approximately 15% of cases, MG is resistant, or refractory to these medicines.

Refractory MG is usually defined when one of these scenarios occurs: a failure to respond to adequate doses of conventional therapies; an inability to reduce use of ISTs without disease worsening, or the need for ongoing rescue therapy, including plasma exchange (PLEX) or intravenous immunoglobulin G (IVIg); severe and intolerable side effects of IST; other conditions that restrict use of conventional therapies; and frequent myasthenic crises.

A myasthenic crisis is a medical emergency that occurs when the muscles that control breathing weaken to the point where patients require a ventilator to help them breathe.

Having refractory MG not only poses a burden to patients’ quality of life. With its associated poor symptom control and greater risk of exacerbations, it likely also requires the use of more healthcare resources.

In fact, a prior study based on U.S. claims data showed that, compared with those with nonrefractory MG, patients with the refractory disease experienced more exacerbations, including crises, visited the emergency room (ER) more frequently, and were hospitalized more often.

Researchers now sought to examine the impact of refractory versus nonrefractory MG on patients’ healthcare resource utilization (HRU) in the U.S., and to confirm prior claims data. To do that, this study used patient-reported data from 825 adults with MG enrolled in the Myasthenia Gravis Foundation of America (MGFA) Patient Registry.

Patients were registered between July 2013 and February 2018, and had been diagnosed with MG for at least two years.

There currently is no widely accepted definition of refractory MG. For the study, participants were classified as having refractory MG if they experienced persistent symptoms after receiving at least two ISTs, or at least one IST and repeated use of IVIg or PLEX in the past, and if they were currently receiving treatment and still had total score of at least 6 in the MG activities of daily living scale (MG-ADL). The MG‐ADL profile is an eight‐item, patient‐reported scale developed to assess MG symptoms and their effects on daily activities.

Among 825 participants, 76 (9.2%) were classified as having refractory MG based on this criteria. The majority (66) were females. The other 749 participants (90.8%, 590 females) were classified as having nonrefractory disease.

During the six months before enrollment, a significantly greater proportion of participants with refractory disease, compared with nonrefractory patients, had experienced at least one MG exacerbation (67.1% vs. 52.0%), had visited an ER at least once (43.4% vs. 27.1%), or had been hospitalized at least once (32.9% vs. 20.5%).

Participants with refractory MG also had been admitted more frequently to an ICU (61.8% vs. 33.4%) for reasons associated with MG. Those with the refractory disease all were more likely to have required a feeding tube (21.1% vs. 9.1%).

A total of 75.8% of younger females with refractory disease (<51 years, 33 patients) experienced at least one exacerbation, with 69.7% admitted to an ICU, and 30.3% requiring a feeding tube. For older females with refractory disease (≥51 years, 33 patients), 60.6% had at least one exacerbation, while 54.6% were admitted to an ICU, and 6.1% required a feeding tube. Between-group differences were not significant.

“Our findings … support the hypothesis that patients with refractory MG have more exacerbations and utilize more healthcare resources than those with nonrefractory MG,” the researchers said.

“Although further research is needed into the difference in the costs of treating refractory and nonrefractory MG, the increased HRU [healthcare resource utilization] of patients with refractory MG suggests higher associated costs,” they added.

Researchers stress this data reaffirms the “need for therapies that are effective against refractory MG, improve outcomes, and reduce the HRU by these patients.”