Symptom burden in patients with idiopathic multicentric Castleman disease and its impact on daily life: an international patient and caregiver survey

Background

Idiopathic Multicentric Castleman Disease (iMCD) is a rare inflammatory lymphoproliferative disorder with heterogenous clinical presentations. The symptomatology in iMCD patients remains poorly understood. The aim of this study was to identify the type, frequency and severity of iMCD-related symptoms and the impact of these on the daily lives of iMCD patients and informal-caregivers.

Methods

We conducted two bespoke 45-question online surveys for iMCD patients and informal-caregivers of patients recruited from the US, UK, Australia and Canada between April 14 and November 8, 2021. Descriptive data was collected, and a Likert scale was used to quantify the impact of symptoms on various aspects of daily life. Ordinal logistic regression analysis was used to determine associations between age, gender, employment status and symptom burden with aspects of daily life.

Findings

Eligible respondents included 51 iMCD patients and 11 informal-caregivers. Patients reported up to 27 unique symptoms, the mean number of symptoms experienced by a patient was 6.7 (range 0-22 symptoms). Most symptoms had a moderate to severe impact on patients' daily lives, with 'pain/discomfort', 'ability to travel', and 'sexual functioning' being the most impacted. iMCD patient characteristics such as being 40 years or older, female, and either disabled or unemployed was significantly associated with adverse impact on several aspects of daily life. Among caregivers, the aspects of daily life that were disproportionately affected was their own social life and freedom, emotional wellbeing, travel/relocation, and work.

Interpretation

iMCD patients have widely varied and unappreciated symptomatology. High symptom burden adversely impacts several aspects of patient daily lives as well as their caregivers.

Funding

Funding was provided by EUSA Pharma.

Cost-Effectiveness Analysis of Siltuximab for Australian Public Investment in the Rare Condition Idiopathic Multicentric Castleman Disease

OBJECTIVES

This paper presents an Australian model that formed part of the health technology assessment for public investment in siltuximab for the rare condition of idiopathic Multicentric Castleman Disease (iMCD) in Australia.

METHODS

Two literature reviews were conducted to identify the appropriate comparator and model structure. Survival gain based on available clinical trial data were modelled using an Excel-based model semi-Markov model including time-varying transition probabilities, an adjustment for trial crossover and long-term data. A 20-year horizon was taken, and an Australian healthcare system perspective was adopted, with both benefits and costs discounted at 5%. The model was informed with an inclusive stakeholder approach that included a review of the model by an independent economist, Australian clinical expert opinion and feedback from the Pharmaceutical Benefits Advisory Committee (PBAC). The price used in the economic evaluation reflects a confidential discounted price, which was agreed to with the PBAC.

RESULTS

An incremental cost-effectiveness ratio of A$84,935 per quality-adjusted life-year (QALY) gained was estimated. At a willingness-to-pay threshold of A$100,000 per QALY, siltuximab has a 72.1% probability of being cost-effective compared with placebo and best supportive care. Sensitivity analyses results were most sensitive to the length of interval between administrations (from 3- to 6-weekly) and crossover adjustments.

CONCLUSION

Within a collaborative and inclusive stakeholder framework, the model submitted to the Australian PBAC found siltuximab to be cost-effective for the treatment of iMCD.