Patient-centred measurement in ophthalmology – a paradigm shift

Ophthalmologists and researchers in ophthalmology understand what a rapidly evolving field ophthalmology is, and that to conduct good research it is essential to use the latest and best methods. In outcomes research, one modern initiative has been to conduct holistic measurement of outcomes inclusive of the patient's point of view; patient-centred outcome. This, of course, means including a questionnaire. However, the irony of trying to improve outcomes research by being inclusive of many measures is that the researcher may not be expert in all measures used. Certainly, few people conducting outcomes research in ophthalmology would claim to be questionnaire experts. Most tend to be experts in their ophthalmic subspecialty and probably simply choose a popular questionnaire that appears to fit their needs and think little more about it. Perhaps, unlike our own field, we assume that the field of questionnaire research is relatively stable. This is far from the case. The measurement of patient-centred outcomes with questionnaires is a rapidly evolving field. Indeed, over the last few years a paradigm shift has occurred in patient-centred measurement

Rasch Analysis of the Upper-Limb Sub-scale of the STREAM Tool in an Acute Stroke Population

Background – Stroke is a leading cause of disability worldwide. The most common impairment resulting from stroke is upper limb weakness. Objectives - To determine the usefulness and psychometric validity of the upper limb sub-scale of the STREAM in an acute stroke population. Methods: Rasch Analysis, including unidimensionality assumption testing, determining model fit, and analysis of: reliability, residual correlations, & differential item functioning. Results - 125 individuals were assessed using the upper limb sub-scale of the Stroke Rehabilitation Assessment of Movement (STREAM) tool. Rasch analysis suggests the STREAM is a unidimensional measure. However, when scored using the originally proposed method (0-2), or using the response pattern (0-5) neither variant fit the Rasch model (p < 0.05). Although, the reliability was good (Person-Separation Index – 0.847 & 0.903 respectively). Correcting for the disordered thresholds, and thereby producing the new scoring pattern, led to substantial improvement in the overall fit (chi-square probability of fit - 22%), however, the reliability was slightly reduced (PSI – 0.806). Conclusions - The study proposes a new scoring method for the upper limb sub-scale of the STREAM outcome measure in the acute stroke population.Stroke Associatio

Cross-cultural validation of the Educational Needs Assessment Tool in RA in 7 European countries

<p>Abstract</p> <p>Background</p> <p>The Educational Needs Assessment Tool (the ENAT) is a 39-item patient questionnaire originally developed in the UK to assess educational needs of patients with rheumatoid arthritis (RA). The objective of this study was to assess the cross-cultural validity of the ENAT in 7 European countries.</p> <p>Methods</p> <p>The ENAT was translated into Dutch, Finnish, Norwegian, Portuguese, Spanish and Swedish versions by using Beaton's cross-cultural adaptation process, and was completed by a convenience sample of patients with RA in each country. The generated country-specific data were assessed for construct validity and were then pooled and assessed for cross-cultural invariance using Rasch analysis.</p> <p>Results</p> <p>Individual country-specific analysis showed adequate fit to the Rasch model after adjustment for local dependency within domains. When data from the different countries were pooled, the 39 items deviated significantly from Rasch model's expectations (X²= 977.055, DF = 351, p = 0.000, PSI = 0.976). Again, most items within domains were found to be locally dependent, significantly affecting the fit. Consequently each domain was treated as a unit (i.e. testlet) and the ENAT was re-analysed as a seven-testlet scale resulting into a good fit to the Rasch model (X²= 71.909; DF = 63; p = 0.207, PSI = 0.951). A test of strict unidimensionality confirmed that all domains contributed to measuring a single construct. Cross-cultural non-invariance was discounted by splitting domains for DIF maintaining an excellent fit to the Rasch model. This allowed calibration of the ENAT into an interval scale.</p> <p>Conclusion</p> <p>The ENAT is a simple tool, which is a valid measure of educational needs of people with RA. Adjustment for cross-cultural non-invariance is available if data from the 7 European countries are to be pooled or compared.</p