Construction of a traditional Chinese medicine syndrome-specific outcome measure: the Kidney Deficiency Syndrome Questionnaire (KDSQ)

Abstract

Background: Development of Traditional Chinese Medicine (TCM) syndrome-specific outcome measures is needed for the evaluation of TCM syndrome-specific therapies. We constructed a Kidney Deficiency Syndrome Questionnaire (KDSQ) for the evaluation of the common TCM syndromes Kidney-Yin Deficiency Syndrome (KDS-Yin) and Kidney-Yang Deficiency Syndrome (KDS-Yang) in middle-aged women with menopausal symptoms.

Methods: KDS-Yin and KDS-Yang were traditionally defined by expert opinion were validated by exploratory factor analysis (EFA) and structural equation modeling (SEM). Content validity was tested by EFA on a sample of 236 women from a seminar and SEM on another sample of 321 women from a postal survey. Other psychometric properties were tested on 292 women from the seminar at baseline and two systematically selected sub-samples: 54 who reported no changes in discomforts 11-12 days after the baseline and 31 who reported changes in discomforts 67-74 days after the baseline. All participants completed the KDSQ, the Greene Climacteric Scale and the standard 12-item Short Form Health Survey.

Results: The EFA and SEM established the measurement models of KDS-Yin and KDS-Yang supporting content validity of the KDSQ. Internal consistency was good (Cronbach's Alpha >0.70). Construct validity was supported by theoretically-derived levels of correlation with the established external measures. Test-retest reliability was strong (ICC(agreement): KDS-Yin, 0.94; KDS-Yang, 0.93). The KDSQ was responsive to changes over time as tested by effect size and longitudinal validity.

Conclusions: The KDSQ was a valid and reliable measure for KDS-Yin and KDS-Yang in Hong Kong Chinese middle-aged women with menopausal symptoms.

Figure 1

The measurement model of KDS-Yin. “Thirsty at night” was identified to measure “Kidney-Essence deficiency” by the EFA was trimmed off by the SEM; whereas this symptom that added to measure “restlessness at night” was validated by the SEM. Of the KDSQ 24 items, 16 measure KDS-Yin, 9 are common items to KDS-Yin and KDS-Yang.

Figure 2

The measurement model of KDS-Yang. The EFA defined five domains but the SEM merged the fifth domain “abnormal water metabolism” to “abnormal urine excretion” for they were found to be highly correlated (>0.90), and this merge was justifiable by the theory. “Urine dripping” and “dizzy spells” were identified by the EFA to measure “Kidney-Qi deficiency” and “deficiency cold”, respectively, were trimmed off by the SEM; whereas these symptoms added to measure “abnormal urine excretion” and “Kidney-Qi deficiency”, respectively, were validated by the SEM. Of the KDSQ 24 items, 17 measure KDS-Yang, 9 are common items to KDS-Yin and KDS-Yang.