Development of a disease model for sporadic inclusion body myositis (Sibm)
sIBM is a progressive idiopathic inflammatory myopathy characterized by the asymmetric atrophy and weakness of proximal and distal muscle groups. Atrophy of the quadriceps, wrist, and finger flexor muscles and dysphagic processes are clinical hallmarks and result in significant functional disabilities with progression. To understand impact on patients, a qualitative study was conducted to support the development of a disease model depicting relationships among patient concepts relevant to disease progression that may be impacted by the treatment of sIBM. No such disease model is currently available.
A literature review was conducted to determine a preliminary understanding of the impact of sIBM. This was followed by therapeutic area expert input and interviews of patients diagnosed with sIBM (n = 20). Based on all results, a model was constructed.
Results from literature and expert input allowed for the development of an initial diagram depicting a proposed pathway from a diagnosis of sIBM, modifying factors (e.g. age, gender, duration, severity, falls), proximal concepts of signs and symptoms of disease (weakness, atrophy), functioning (upper extremity, lower extremity, general, swallowing) and through more distal psychosocial concepts (emotions, mood, relationships). Patient feedback was used to further refine the model. Some physical impacts were described as difficulty standing from a seated position or using stairs in early disease followed by increased falls, gait impairment, and progressive loss of ambulation resulting in the need for assistive devices. Upper extremity weakness results in difficulty with activities requiring gripping and lifting. Dysphagia can include swallowing difficulties, choking, and interference with nutritional intake. Psychosocial impacts were often related to the loss of autonomy, fear of falls, social and familial impacts and the need for assistance.
This sIBM disease model adds significantly to the literature describing the patient impact of sIBM and may be used to guide selection of clinical trial endpoints.