The shoulder function index (SFInX): a clinician-observed outcome measure for people recovering from a proximal humeral fracture

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the Department of Physiotherapy, School of Allied Health, Faculty of Health Sciences, La Trobe University, Bundoora.

This thesis describes the development of a new outcome measure for ‘shoulder function’, the Shoulder Function IndeX (SFInX), for people with a proximal humeral fracture. A systematic review identified seventeen existing shoulder outcome measures used in this population, four of which had undergone limited psychometric evaluation. Subsequently, content and psychometric properties of five measures were evaluated. All measures included items from multiple domains of the International Classification of Functioning, Disability and Health, which might limit their ability to measure a single dimension such as ‘shoulder function’, the ability to perform daily tasks and activities in which the shoulder is involved. Also, relatively low absolute agreement between repeated measurements using the same tool (up to 23 percent of available score range) might limit their use as outcome measures in individuals. Concerns about content, psychometric properties and measurement methods of existing measures motivated the development of a unidimensional outcome measure for ‘shoulder function’ that is psychometrically sound and easy to administer. The SFInX is a 13-item clinician-observed outcome measure. Patients are asked to perform tasks, and completion of tasks is judged by a clinician as ‘able’, ‘partially able’ or ‘unable’. The SFInX has been developed with involvement of patients and clinicians, has undergone Rasch analysis and has been evaluated psychometrically using data from 92 people recovering from a proximal humeral fracture. Psychometric evaluation included intra-rater reliability, inter-rater reliability and measurement error; convergent, discriminant and known-groups validity; longitudinal validity (responsiveness); and minimal clinically important differences, floor and ceiling effects. The SFInX is a promising outcome measure to monitor ‘shoulder function’ of people with a proximal humeral fracture for rehabilitation and research purposes. It has content relevant to patients and clinicians, is feasible for testing in clinical and home settings, is a unidimensional measure of ‘shoulder function’ and has sound psychometric properties in this population.