Body weight distribution of US patients with myasthenia gravis

Several novel therapies have been approved for treatment of generalized myasthenia gravis (gMG). The dosing requirements of certain therapies (efgartigimod intravenous, nipocalimab, ravulizumab, rozanolixizumab, zilucoplan) are based on patient's body weight. To determine costs of weight-based gMG treatments to payers, accurate assessment of the body weight distribution of patients with MG is required. However, little is known about these patients' weight profile. The current study aims to provide robust weight data in multiple cohorts of patients with MG and elucidate the cost of gMG therapies based on weight.

Body weight distribution of patients with MG was analyzed using Optum's de-identified Market Clarity Data and data from the efgartigimod patient support program (PSP). Adult patients with MG with available body weight were included. Additionally, a literature review of clinical trials of gMG therapies that reported patient body weight was conducted. An analysis of the annual cost of weight-based dosing was also performed.

Patients from the Optum database (N = 5,033) had mean body weight = 86.6 kg (standard deviation [SD] = 23.1 kg) and median weight = 83.7 kg (interquartile range [IQR] 70.3-99.9 kg). Patients from the PSP (N = 4,539) had mean weight = 92.1 kg (SD = 25.6 kg) and median weight = 89.0 kg (IQR = 74.0-106.1 kg). In each cohort, most patients weighed ≥80 kg (58.0% Optum, 66.2% PSP). Across clinical trials of patients with gMG, mean body weights ranged from 79.1-91.2 kg and median weights from 74.4-90.0 kg. The annual cost of health-care-provider-administered treatment for patients with gMG was estimated at $223,272-$648,960 depending on drug and body weight; annual cost was highest for patients who weighed >80 kg (up to $648,960 versus up to $467,044 for patients who weighed <80 kg).

Our findings demonstrate that patients with MG may be heavier on average than previously assumed, which may influence the cost-effectiveness of gMG therapies with weight-based dosing.