OBJECTIVE: The aims of this study were to develop the cut off value of Yin deficiency questionnaire for diagnosis of Yin deficiency and compare diagnostic ability between Yin deficiency questionnaire(YDQ) and Yin deficiency scale score(YDS) in xerostomia patients.

METHOD: We recruited 58 xerostomia patients. The subjects were diagnosed as yin deficiency and non yin deficiency by 3 korean medicine doctors. We assessed patients condition of yin deficiency using YDQ and YDS. We surveyed their oral dryness using VAS of Xerostomia, the Dry Mouth Symptom Questionnaire (DMSQ), Stimulated Salivary Flow Rate(SSFR), Unstimulated Salivary Flow Rate(USFR), Oral moisture on buccal mucosa(OMB) and Oral moisture on tongue surface(OMT). And we also surveyed their tongue coatings using Winkel Tongue Coating Index(WTCI).

RESULTS: We diagnosed 23 of 58 patients as yin deficiency and 35 of 58 patients as non yin deficiency. There were no significant difference of age, sex distribution and body mass index between yin deficiency group and non yin deficiency group. Using receiver operating characteristic curve analysis optimal cut off value of YDQ was defined as 304, and it’s sensitivity, specificity and Youden index were 86.96%, 71.43% and 1.5839. To assess degree of agreement between korean medicine doctor’s diagnosis and YDQ diagnosis, Cohen’s coefficient of agreement was computed and Cohen’s kappa of YDQ was 0.524. Using pearson’s correlation analysis, we found that concurrent validity of YDQ and YDS was statically significant correlated. To compare diagnostic ability between YDQ and YDS, area under curve value(AUC) was calculated, AUC of YDS and YDQ were 0.802 and 0.758, and there were no significant difference(p=0.505). But there were statistically significant strong correlations between DMSQ-symptom and YDQ(r=0.731, p<0.001), weak correlations between DMSQ-behavior and YDQ(r=0.350, p<0.01). There were intermediate correlations between DMSQ-symptom and YDS(r=0.418, p<0.01), weak correlation between DMSQ-behavior and YDS(r=0.283, p<0.05).

CONCLUSIONS: The results shows that the cut off value of YDQ can help to provide diagnostic assesment to yin deficiency in xerostomia. And diagnostic ability of YDQ in xerostomia is better than YDS.