Clinical burden and healthcare resource utilization associated with myasthenia gravis: Assessments from a Japanese claims database

Abstract

Objectives To compare the burden of illness for refractory and non‐refractory myasthenia gravis (MG) in Japanese patients. Methods Adults in a large Japanese health insurance claims database (1 September 2008 to 31 October 2016) were included in this retrospective, observational study if they had: at least two separate claims coded as MG by a neurologist; and continuous enrollment for 12 months after any MG claim (non‐refractory cohort) or the earliest claim associated with refractory disease (refractory cohort). A cohort with Parkinson's disease was used as the reference for the burden of illness of MG, and comprised patients matched (sex, age and index date) to patients with MG. Outcomes included respiratory failure, myasthenic exacerbations, outpatient hospital and emergency room visits, and hospitalizations. Results A significantly greater proportion of the refractory cohort (n = 165) than the non‐refractory cohort (n = 3137) experienced respiratory failure (17.0% vs 5.5%, respectively; P < 0.001) and/or exacerbations (57.6% vs 5.8%, respectively; P < 0.001) over 12 months. The mean numbers of hospitalizations (0.68 vs 0.09/year), emergency room visits (0.07 vs 0.03/year) and outpatient hospital visits (16.79 vs 11.88/year), and the mean duration of hospital stays (22.19 vs 2.81 days/year) were also significantly greater for the refractory cohort (all P < 0.001). Except for emergency room visits, healthcare resource utilization was significantly greater for non‐refractory MG than for Parkinson's disease (n = 3168). Conclusions In Japanese patients, refractory MG is associated with a greater clinical burden and healthcare resource utilization than non‐refractory MG.

Healthcare resource utilization by patients with treatment-refractory myasthenia gravis in England

“…The study showed that patients in England with refractory MG visit healthcare providers more frequently, are hospitalized more often and visit an ER more often than patients with non-refractory MG. These findings agree with recent analyses of US and Japanese health insurance claims data, which used similar algorithms to identify refractory patients 15,18 . The largest difference in resource utilization between the refractory and non-refractory MG cohorts was for inpatient hospitalization.…”

“…As a result, patients with refractory MG spent more total time in hospitals since diagnosis than patients with non-refractory MG. These results are in line with those from the US and Japanese studies 15,18 and indicate that patients with refractory MG more frequently experience serious or life-threatening exacerbations and crises than patients with non-refractory MG.…”

“…We found that thymectomy was performed for only 2.6% of MG patients overall (6.1% for refractory MG and 2.4% for non-refractory MG) at any time after the index date and 1.7% within the first 12 months after the index date (4.6% for refractory MG and 1.6% for non-refractory MG). This is in line with rates of thymectomy within 12 months of the index date reported in the studies of US claims data (1.8% overall, 5.5% for refractory MG, 1.4% for non-refractory MG) 15 and Japanese claims data (1.6% overall, 5.5% for refractory MG, 1.4% for non-refractory MG) 18 . The relatively low rates may be because most of the MG patients in these studies were older than 45 years of age at the index date.…”

“…In the current study, 5.6% of MG patients were refractory, which is lower than the rates reported in the US study (9.6%) 15 and in two other previous studies (10-15%) 16,17 but similar to a recent Japanese study (5.0%) 18 . The US study also found that patients with refractory MG were more likely to be female, younger and to have more comorbidities than patients with non-refractory MG 15 , although the differences were small.…”

“…A smaller study that included patients referred to a tertiary neuromuscular clinic in the US found that refractory patients were younger at the onset of MG and more likely to be female, thymomatous and positive for antibodies to muscle-specific receptor tyrosine kinase 16 . A recent study of Japanese claims data found that 5.0% of patients with MG were refractory to conventional treatment and that patients with refractory MG were more likely than patients with non-refractory MG to experience respiratory failure and exacerbations each year, and to be hospitalized, visit an ER or have an outpatient hospital visit 18 .…”