成人型アトピー性皮膚炎患者の痒みに対する不安の研究 : 構造方程式モデリングを用いて  [in Japanese] Effect of "Anxiety to Itch" in Adult Atopic Dermatitis Patients : by use of Structural Equation Modeling  [in Japanese]

本研究の目的は,構造方程式モデリングを用いて成人型アトピー性皮膚炎(成人型AD)患者の痒みに対する不安とそう痒,掻破行動,健康関連QOLの因果関係について検討し,痒みに対する不安モデルを構築することであった.モデルの適合度を算出した結果,痒みに対する不安モデルは痒みに対する不安からそう痒,掻破行動を介して健康関連QOLへ影響を及ぼすモデルであることが示された.各影響度は,痒みに対する不安からそう痒へはγ=0.84,そう痒から掻破行動へはr=0.91,そして掻破行動から健康関連QOLへはγ=O.73であった.以上の結果から,成人型AD患者の健康関連QOLの低下は,痒みに対する不安がそう痒や掻破行動へ影響を及ぼした結果生じていると考えられる.今後,成人型AD患者の健康関連QOLを向上させるためには,痒みに対する不安を治療対象とする必要があると考えられる.

Objective: It has been indicated that atopic dermatitis (AD) has association with health related quality of life (HRQOL) because it can have an impact on work, sleep and social relations (Kiebert et al., 2002). Anxiety in the adult AD patient has an influence on the itch related to deterioration of the symptom and particularly, scratching behavior and it is suggested that anxiety reduced HRQOL. In the previous study, it was made clear that the adult AD patient also holds "anxiety to itch". However, it remains still unclear how "anxiety to itch" relates to the "itch" and "scratching behavior", which influence the HRQOL. The purpose of this study is to investigate the causal relationship among "anxiety to itch", "itch", "scratching behavior", and the "disease specific HRQOL" for adult AD patients by using Structural Equation Modeling (SEM). Method: Subjects were 50 adult AD patients. The "anxiety to itch" was measured by using the Itch Anxiety Scale for Atopic Dermatitis (IAS-AD: Himachi et al., 2007). Itch was measured using the Numerical Rating Scale (NRS), scratching behavior was measured using the scratching checklist (Tsutsui, 1999), and the disease specific HRQOL was measured using the skindex29 (Fukuhara, 2004). Results: Mean score on the IAS-AD was 51.07 (SD=12.73), an itch was 73.19 (SD=34.31), strength of scratching behavior was 20.20 (SD=10.54), length of scratching behavior was 19.40 (SD=11.78), and Skindex29 was 38.41 (SD=25.05). Two causal models were hypothesized referring to the previous studies and were compared by using the structural equation modeling (SEM). The result of comparison between two causal models showed that the model that "anxiety of itch" influences "itch" (r=0.84), "itch" influences "scratching behavior" (r=0.91), and "scratching behavior" influences "HRQOL" (r=0.73) is more suitable (χ^2=14.78, df=13, p=0.32, AIC=44.784, BIC=73.465, GFI=0.925, AGFI=0.835, CFI=0.995, RMSEA=0.053). Conclusion: It is concluded that the high level of "itch to anxiety" increases in itch and itch increases scratching behavior, and scratching behavior adversely effects "itch to anxiety" on HRQOL in adult AD patients. In order to improve the HRQOL of adult AD patients, it is necessary to develop the treatment method which focuses on "itch to anxiety".