Little is known about the frequency of relapses and relapse-associated healthcare resource utilization (HCRU) among patients with neuromyelitis optica spectrum disorder (NMOSD), a rare, autoimmune condition characterized by unpredictable relapses affecting the optic nerves and spinal cord that can lead to blindness, paralysis, and premature death.
A retrospective, observational cohort analysis was conducted to characterize the rate of relapses and relapse-associated HCRU among patients with NMOSD in US clinical practice.
Data from the IQVIA PharMetrics Plus Healthcare Claims Database were used to identify adults (aged ≥18 years) with evidence of NMOSD (≥1 inpatient diagnosis or ≥2 outpatient diagnoses) between January 2013 and March 2018. Relapses were defined by hospital admissions for NMOSD-related conditions and ambulatory encounters for disease-related treatment. Relapse-associated HCRU was characterized by care setting, relapse duration, reason for admission (inpatient), and drug therapy (outpatient). Relapse rates per patient were annualized to adjust for differential follow-up (maximum 6 years). HCRU was described per relapse.
The study population included 1,363 patients with NMOSD. The mean age was 45 years (standard deviation [SD]: 13 years), 75% of the cohort was female, and many patients had a recent history of drug therapy. The mean follow-up duration was 2.4 years (SD: 1.5 years). Among all patients, the annualized number of relapses was 0.8 (95% confidence interval [CI]: 0.7–0.9), and the annualized relapse duration was 12.8 days (95% CI: 11.2-14.4 days). Among patients with ≥1 relapse (48% of all patients), 28% had a relapse duration of <5 days, 18% had a relapse duration of 5-9 days, 18% had a relapse duration of 10-19 days, and 36% had a relapse duration of ≥20 days. More than one-third of all relapses required inpatient care (1◦ diagnosis: neuromyelitis optica 66%; optic neuritis 10%; transverse myelitis 20%). The mean hospital length of stay was 14.6 days (95% CI: 13.9-15.2 days). Relapses requiring outpatient care were typically treated with intravenous (IV) methylprednisolone (60%), IV immunoglobulin (36%), and/or plasma exchange (11%).
In this large study of patients with NMOSD in US clinical practice, almost one-half of patients experienced ≥1 relapse during follow-up. Among these patients, most experienced multiple relapses, and relapses requiring extended hospital stays were common.