Skip to main content

Table 6 Developing a PCOM de novo: an example of best practice – the Performance of the Upper Limb (PUL) module for DMD [35]

From: Measuring what matters to rare disease patients – reflections on the work by the IRDiRC taskforce on patient-centered outcome measures

Objective: To develop a new measure suitable to cover all the aspects of upper limb function – a concept valued across the whole spectrum of DMD patients (i.e. from younger ambulant to older weaker adults who may only have limited finger movements).
An iterative and multi-stakeholder process: Development of the PUL involved several steps: [1] A systematic review was performed to identify existing measures assessing upper extremity functional aspects used in DMD. Only four ClinROs were found to have been previously used in DMD; [2] An exploratory study was performed to assess the suitability of the existing scales across 61 DMD patients aged 11–30 years. The study identified shortcomings related to posture, pattern of weakness and contractures requiring compensatory strategies; [3] A conceptual model reflecting the progression of weakness and natural history of functional decline in DMD was hypothesized during a multi-stakeholder workshop. Functional tasks were subdivided into three main levels reflecting disease progression from proximal to distal and different stages of the disease: shoulder dimension, elbow dimension, and wrist and finger dimension; [4] An initial set of items was determined based on expert opinion, input from patients and families. Items were refined, added, or eliminated based on feedback; [5] An iterative consultative process with patients, families as well as experts ensured that items in PUL were clinically meaningful and relevant to DMD. Patients and families identified gaps in the proposed assessment; [6] A preliminary pro forma was developed and piloted in 86 patients across seven international sites in Europe and the USA; [7] Rasch analysis was used to create a scale and to review item fit to the underlying construct. A revised version of the PUL including 22 items and a manual were developed and agreed by all the participants. The PUL continues to be reviewed.
Impact: A multi-stakeholder collaboration, where patients with DMD and their families had a prominent role, was key to the successful development of the PUL. Modern psychometric methods were used to create a scale with robust internal reliability and validity.