The trial showed that the conventional slow tapering regimen enabled discontinuation of prednisone earlier than previously reported but the new rapid-tapering regimen enabled an even faster discontinuation.
Noting that although both regimens led to a comparable myasthenia gravis status and prednisone dose at 15 months, the authors state: “We think that the reduction of the cumulative dose over a year (equivalent to 5 mg/day) is a clinically relevant reduction, since the risk of complications is proportional to the daily or cumulative doses of prednisone.
“Our results warrant testing of a more rapid-tapering regimen in a future trial. In the meantime, our trial provides useful information on how prednisone tapering could be managed in patients with generalized myasthenia gravis treated with azathioprine,” they conclude.
The trial was published online February 8 in JAMA Neurology.
Myasthenia gravis is a disorder of neuromuscular transmission, resulting from autoantibodies to components of the neuromuscular junction, most commonly the acetylcholine receptor. The incidence ranges from 0.3 to 2.8 per 100,000, and it is estimated to affect more than 700,000 people worldwide.
The authors of the current paper, led by Tarek Sharshar, MD, PhD, Groupe Hospitalier Universitaire (GHU), Paris, France, explain that many patients whose symptoms are not controlled by cholinesterase inhibitors are treated with corticosteroids and an immunosuppressant, usually azathioprine. No specific dosing protocol for prednisone has been validated, but it is commonly gradually increased to 0.75 mg/kg on alternate days and reduced progressively when minimal manifestation status (MMS; no symptoms or functional limitations) is reached.
They note that this regimen leads to high and prolonged corticosteroid treatment — often for several years — with the mean daily prednisone dose exceeding 30 mg/day at 15 months and 20 mg/day at 36 months. As long-term use of corticosteroids is often associated with significant complications, reducing or even discontinuing prednisone treatment without destabilizing myasthenia gravis is therefore a therapeutic goal.
To investigate whether different dosage regimens could help wean patients with generalized myasthenia gravis from corticosteroid therapy without compromising efficacy, the researchers conducted this study in which the current recommended regimen was compared with an approach using higher initial corticosteroid doses followed by rapid tapering.
In the conventional slow-tapering group (control group), prednisone was given on alternate days, starting at a dose of 10 mg then increased by increments of 10 mg every 2 days up to 1.5 mg/kg on alternate days without exceeding 100 mg. This dose was maintained until MMS was reached and then reduced by 10 mg every 2 weeks until a dosage of 40 mg was reached, with subsequent slowing of the taper to 5 mg monthly. If MMS was not maintained, the alternate-day prednisone dose was increased by 10 mg every 2 weeks until MMS was restored, and the tapering resumed 4 weeks later.
In the new rapid-tapering group, oral prednisone was immediately started at 0.75 mg/kg/day, and this was followed by an earlier and rapid decrease once improved myasthenia gravis status was attained. Three different tapering schedules were applied dependent on the improvement status of the patient.
First, If the patient reached MMS at 1 month, the dose of prednisone was reduced by 0.1 mg/kg every 10 days up to 0.45 mg/kg/d, then 0.05 mg/kg every 10 days up to 0.25 mg/kg/d, then in decrements of 1 mg by adjusting the duration of the decrements according to the participant’s weight with the aim of achieving complete cessation of corticosteroid therapy within 18-20 weeks for this third stage of tapering.
Second, if the state of MMS was not reached at 1 month but the participant had improved, a slower tapering was conducted, with the dosage reduced in a similar way to the first instance but with each reduction introduced every 20 days. If the participant reached MMS during this tapering process, the tapering of prednisone was similar to the sequence described in the first group.
Third, if MMS was not reached and the participant had not improved, the initial dose was maintained for the first 3 months; beyond that time, a decrease in the prednisone dose was undertaken as in the second group to a minimum dose of 0.25 mg/kg/day, after which the prednisone dose was not reduced further. If the patient improved, the tapering of prednisone followed the sequence described in the second category.
Reductions in prednisone dose could be accelerated in the case of severe prednisone adverse effects, according to the prescriber’s decision.
In the event of a myasthenia gravis exacerbation, the patient was hospitalized and the dose of prednisone was routinely doubled, or for a more moderate aggravation, the dose was increased to the previous dose recommended in the tapering regimen.
Azathioprine, up to a maximum dose of 3 mg/kg/d, was prescribed for all participants. A total of 117 patients were randomly assigned, and 113 completed the study.
The primary outcome was the proportion of participants having reached MMS without prednisone at 12 months and having not relapsed or taken prednisone between months 12 and 15. This was achieved by significantly more patients in the rapid-tapering group (39% vs 9%; risk ratio, 3.61; P < .001).
Rapid tapering allowed sparing of a mean of 1898 mg of prednisone over 1 year (5.3 mg/day) per patient.
The rate of myasthenia gravis exacerbation or worsening did not differ significantly between the two groups, nor did the use of plasmapheresis or IVIG or the doses of azathioprine.
The overall number of serious adverse events did not differ significantly between the two groups (slow tapering, 22% vs rapid-tapering, 36%; P = .15).
The researchers say it is possible that prednisone tapering would differ with another immunosuppressive agent but as azathioprine is the first-line immunosuppressant usually recommended, these results are relevant for a large proportion of patients.
They say the better outcome of the intervention group could have been related to one or more of four differences in prednisone administration: an immediate high dose vs a slow increase of the prednisone dose; daily vs alternate-day dosing; earlier tapering initiation; and faster tapering. However, the structure of the study did not allow identification of which of these factors was responsible.
“Researching the best prednisone-tapering scheme is not only a major issue for patients with myasthenia gravis but also for other autoimmune or inflammatory diseases, because validated prednisone-tapering regimens are scarce,” the authors say.
The rapid tapering of prednisone therapy appears to be feasible, beneficial, and safe in patients with generalized myasthenia gravis and “warrants testing in other autoimmune diseases,” they add.
Particularly Relevant to Late-Onset Disease
Commenting on the study for Medscape Medical News, Raffi Topakian, MD, Klinikum Wels-Grieskirchen, Wels, Austria, said the results showed that in patients with moderate-to-severe generalized myasthenia gravis requiring high-dose prednisone, azathioprine, a widely used immunosuppressant, may have a quicker steroid-sparing effect than previously thought, and that rapid steroid tapering can be achieved safely, resulting in a reduction of the cumulative steroid dose over a year despite higher initial doses.
Topakian, who was not involved with the research, pointed out that the median age was advanced (around 56 years), and the benefit of a regimen which leads to a reduction of the cumulative steroid dose over a year may be disproportionately larger for older, sicker patients with many comorbidities who are at considerably higher risk for a prednisone-induced increase in cardiovascular complications, osteoporotic fractures, and gastrointestinal bleeding.
“The study findings are particularly relevant for the management of late-onset myasthenia gravis (when first symptoms start after age 45-50 years), which is being encountered more frequently over the past years,” he commented.
“But the holy grail of myasthenia gravis treatment has not been found yet,” Topakian noted. “Disappointingly, rapid tapering of steroids (compared to slow tapering) resulted in a reduction of the cumulative steroid dose only, but was not associated with better myasthenia gravis functional status or lower doses of steroids at 15 months. To my view, this finding points to the limited immunosuppressive efficacy of azathioprine.”
He added that the study findings should not be extrapolated to patients with mild presentations or to those with muscle-specific kinase (MuSK) myasthenia gravis.
Sharshar has disclosed no relevant financial relationships. Disclosures for the study coauthors appear in the original article.
JAMA Neurol. Published online February 8, 2021. Abstract