Objective: This study explores, based on the International Classification of Functioning, Disability and Health, the consequences of different operationalizations of participation in regression models predicting participation in one sample of patients. Design: Cross-sectional, comparative study. Setting: Department of Neurology of a University Hospital. Subjects: A total of 677 patients with a Neuromuscular Disease. Measures: Participation was measured using the Neuromuscular Disease Impact Profile questionnaire, the RAND-36 Item Health Survey (social functioning, role limitations—physical, role limitations—emotional) and the Impact on Participation and Autonomy questionnaire (autonomy outdoors, social relations). Potential predictors of participation included type of neuromuscular disease, body functions (measured with Neuromuscular Disease Impact Profile), activities (measured with Neuromuscular Disease Impact Profile), environmental factors (measured with Neuromuscular Disease Impact Profile), and personal factors (measured with the 13-item Sense of Coherence questionnaire). The results were controlled for patient characteristics. Results: Participation was statistically predicted by different determinants depending on the operationalization used for participation. Additionally, the regression coefficients differed significantly. Body functions and activities were predictors in five out of six operationalizations of participation. Sense of coherence predicted participation in all of the operationalizations. The explained variance of the different models ranged from 25% (RAND-36 role limitations—emotional) to 65% (Neuromuscular Disease Impact Profile). Conclusions: Different operationalizations of participation result in different prediction models. Lack of conceptual consensus makes participation an ambiguous concept in research, and this ambiguity makes evidence-based decisions directed at enhancing participation difficult. Participation needs to be operationalized in an unambiguous and standard way in order to improve the comparability of outcomes.
Development and testing psychometric properties of an ICF-based health measure: The Neuromuscular Disease Impact Profile
