Exploring the construct validity of the Patient Perception Measure – Osteopathy (PPM-O) using classical test theory and Rasch analysis

Abstract

BackgroundEvaluation of patients’ experience of their osteopathic treatment has recently been investigated leading to the development of the Patient Perception Measure – Osteopathy (PPM-O). The aim of the study was to investigate the construct validity of the PPM-O.MethodsPatients presenting to osteopathy student-led teaching clinics at two Australian universities were asked to complete two questionnaires after their treatment: a demographic questionnaire and the PPM-O. Confirmatory factor analysis (CFA) and Rasch analysis were used to investigate the construct validity of the PPM-O.ResultsData from the present study did not fit the a-priori 6-domain structure in the CFA. Modifications to the 6-domain model were then made based on the CFA results, and this analysis identified two factors: 1) Education & Information (9 items); and 2) Cognition & Fatigue (6 items). These two factors were Rasch analysed individually. Two items were removed from the Cognition & Fatigue factor during the analysis. The two factors independently were unidimensional.ConclusionsThe study produced a 2-factor, 13-item questionnaire that assesses the patients’ perception of their osteopathic treatment using the items from a previous questionnaire. The results of the current study provide evidence for the construct validity of the PPM-O and the small number of items makes it feasible to implement into both clinical and research settings. Further research is now required to establish the measures’ validity in a variety of patient populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12998-015-0055-x) contains supplementary material, which is available to authorized users.

Evaluation of New Zealand osteopathy patients experiences of their treatment

“…The PPM-O is a 13-item self-report measure (17) designed to identify patient perceptions and selfreported outcomes of osteopathic treatment. The questionnaire has been used to assess patients' experiences of both cranial and structural osteopathic treatment.…”

“…The questionnaire has been used to assess patients' experiences of both cranial and structural osteopathic treatment. Previous work (17) using both confirmatory factor analysis and Rasch analysis suggests the items load onto two factors: 'Education and Information' (9 items), and 'Cognition and Fatigue' (4 items). Items are answered on a five-point Likert scale, and include both positively and negatively worded statements.…”

“…This data analysis has been employed in a previous study involving the PPM-O and its precursors (15). Cronbach's alpha was calculated as the reliability estimate for each of the individual subscales, as per Mulcahy and Vaughan (17).…”

“…A lack of data on patient perception and treatment outcomes associated with OCF lead Mulcahy et al (16) to develop a questionnaire to collect and analyse patient experiential data. Originally intended only for patients receiving OCF (16), the questionnaire was later revised and condensed using both confirmatory factor analysis and Rasch analysis (17). The questionnaire was titled the Patient Perception Measure -Osteopathy (PPM-O) and these authors suggested that it may be useful to evaluate both 'cranial' and 'structural' osteopathic treatments (15,17).…”

“…Originally intended only for patients receiving OCF (16), the questionnaire was later revised and condensed using both confirmatory factor analysis and Rasch analysis (17). The questionnaire was titled the Patient Perception Measure -Osteopathy (PPM-O) and these authors suggested that it may be useful to evaluate both 'cranial' and 'structural' osteopathic treatments (15,17). In further work Mulcahy and Vaughan (15) also observed that the sensations patients experience during their OCF treatment may be associated with how those patients perceive their treatment.…”