Development of the 8-Item Phlegm Pattern Questionnaire (PPQ-8) Using Rasch Analysis

Abstract

The 25-item Phlegm Pattern Questionnaire (PPQ) has been widely used to examine the relationship between the phlegm pattern (PP), quality of life, tongue colour, vocal qualities, and dysfunctional breathing. However, the concerns of response burden and differences in the respondent’s abilities or item difficulty for the original version of the PPQ have not been sufficiently addressed. This study aimed to develop a short-form PPQ using Rasch analysis, an item response theory. Based on the retrospective data, the response order, differential item functioning (DIF), dimensionality, reliability, concurrent validity, and fitting errors were examined for 291 normal participants and 61 inpatients. The discriminative ability of the short-form PPQ was examined using receiver operating characteristic curve analysis. Along with Rasch analysis, another short-form PPQ was developed using equidiscriminative item-total correlation (EITC) analysis and the results between the two short-form PPQs were compared accordingly. Rasch analysis results suggested a 6-point response category for the PPQ, and finally, 8 items without fitting errors or DIF variability were selected for the PPQ (PPQ-8). The PPQ-8 had satisfactory reliability (person separation index = 2.23), unidimensionality (unexplained variance in the first contrast = 1.598), fitting levels (infit mean square, 0.80–1.39; outfit mean square, 0.79–1.34), sensitivity (70.5%), and specificity (76.5%). The PPQ-8 had a moderate discriminative ability of the PP (area under the curve = 0.759), and the cut-off point was 23. Although the 8-item PPQ developed using EITC analysis showed similar levels of reliability, validity, and discriminative ability of the PP to the PPQ-8, it could not present the information of item hierarchy and differences in the respondents’ abilities. In conclusion, the PPQ-8 by Rasch analysis is recommended for future use to evaluate the clinical severity of PP.

Development of the Short-Form Yin Deficiency Scale Using Three Item Reduction Approaches

“…Rasch analysis clarifed the response category of the 27-item YDS by modifying the 7-point response scale of the original version of the YDS to fve points. Te response category of the fve points of the short-form YDS was lower than that of the short-form Phlegm Pattern Questionnaire, where 6point categories were fnally determined using Rasch analysis [36]. After modifying the response category, 11 items with DIF regarding sex and age distribution and two items with inft or outft errors were removed from the twenty-seven items of the YDS, and fnally, fourteen items were determined.…”

A Review of Cold-Wet Mizaj and Phlegm Dominance Indices in Persian Medicine

“…An instance is phlegm patterns in TCM, which are similar to phlegm disorder in PM in terms of name and some characteristics. The common indices of phlegmatic disorders in PM and TCM include phlegmatic post-nasal discharge, nervous system disorders such as headache and sleepiness, digestive disorders such as indigestion, poor appetite, stomach fullness, and mucous stool, feeling of heaviness or weakness in the limbs, fatigue, and joint pain (13,(45)(46)(47). Considering the importance of diagnosis and the association between phlegm patterns and various diseases including cardiovascular disorders, TCM researchers have developed standard diagnostic questionnaires (13,47).…”

“…For instance, some disease classifications in Traditional Chinese Medicine (TCM) are relatively similar to Mizaj classifications in PM. In this regard, a large group of TCM diseases is known as phlegm pattern diseases (47,48). The indices specified for diagnosis of this pattern are very similar to those of cold-wet dystemperament and phlegm dominance in PM (13,47).…”

“…In this regard, a large group of TCM diseases is known as phlegm pattern diseases (47,48). The indices specified for diagnosis of this pattern are very similar to those of cold-wet dystemperament and phlegm dominance in PM (13,47). TCM researchers have developed standard questionnaires to detect phlegm patterns, with research and clinical applications (47,49).…”