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Audit of Diabetes-Dependent Quality of Life (ADDQoL) [Chinese version for Singapore] questionnaire

Reliability and validity among Singaporeans with type 2 diabetes mellitus

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Abstract

Background

The Audit of Diabetes-Dependent Quality of Life (ADDQoL) questionnaire is an individualized instrument that measures the impact of diabetes mellitus on quality of life (QOL). With the worldwide increase in the number of Chinese people diagnosed with diabetes, we anticipated that a Chinese-language version of the ADDQoL would be urgently needed.

Objective

To evaluate the reliability and validity of the ADDQoL (Chinese version for Singapore) among Chinese-speaking Singaporeans with type 2 diabetes mellitus (T2DM).

Methods

Chinese versions of the ADDQoL, EuroQoL-Visual Analogue Scale (EQ-VAS), EQ-5D and SF-6D were administered to Chinese-speaking participants with T2DM (aged ≥21 years) at a tertiary acute-care hospital by convenience sampling. The ADDQoL was assessed for the following: internal consistency (Cronbach’s alpha); test-retest reliability (intraclass correlation coefficient [ICC]); factor structure; known-groups validity (insulin requiring vs non-insulin requiring, with vs without diabetes-related complications, overweight/obese vs not overweight/obese); and convergent and divergent validity (with EQ-VAS, EQ-5D and SF-6D). The usefulness of weighting and ‘not applicable’ (NA) options (key features of ADDQoL) were also evaluated.

Results

In 88 participants (58% male, mean [SD] age 56.6 [11.74] years), the mean (SD) ADDQoL average weighted impact (AWI) score was −2.613 (1.899). Cronbach’s alpha was 0.941 and the ICC was 0.955 (95% CI 0.812, 0.990). In confirmatory factor analysis, the hypothesized one-factor solution was supported. ADDQoL AWI scores correlated strongly with ADDQoL diabetes-dependent global QOL scores (Spearman’s rank correlation coefficient [rs] = 0.5983) and weakly with generic measures (rs = −0.028 for ADDQoL present global QOL scores, 0.310 for EQ-VAS, 0.164 for EQ-5D and 0.281 for SF-6D). Participants who required insulin, those with diabetes-related complications and those who were overweight/obese reported lower AWI scores, but the differences were not statistically significant. Importance scores of zero were assigned 1–28% of the time and the NA options were selected 3–49% of the time.

Conclusions

The ADDQoL is reliable and probably valid for assessing QOL among Chinese-speaking Singaporeans with T2DM, although known-groups validity warrants further investigation.

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Acknowledgements

The authors would like to express their appreciation to Professor Clare Bradley, developer of the ADDQoL, and her staff, Ms Rosalind Plowright, for their valuable input to an initial draft of this article. The authors would also like to thank Ms Zhang Xuhao and Ms Tipaporn Pongmesa for their assistance in data collection; staff of the Diabetes Centre at the Singapore General Hospital for their assistance in study logistics; and Ms Regine Lim, Ms Tipaporn Pongmesa, Ms Zhao Yingjiao and Ms Mandy Ow for their assistance in the typesetting of the manuscript.

The ADDQoL 19 in the original English and other available languages are available from the copyright holder Professor Clare Bradley via her website http://www.healthpsychologyresearch.com.

The authors have no conflicts of interest that are directly relevant to the content of the article.

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Authors and Affiliations

  1. Department of Pharmacy, National University of Singapore, 18 Science Drive 4, Singapore, 117543, Republic of Singapore

    Swee Sung Soon, Jiat Ling Poon, Shu Chuen Li & Hwee Lin Wee (Assistant Professor)

  2. Department of Endocrinology, Singapore General Hospital, Singapore, Republic of Singapore

    Su Yen Goh & Yong Mong Bee

  3. Discipline of Pharmacy and Experimental Pharmacology, School of Biomedical Sciences, University of Newcastle, New South Wales, Australia

    Shu Chuen Li

  4. Department of Rheumatology and Immunology, Singapore General Hospital, Singapore, Republic of Singapore

    Julian Thumboo & Hwee Lin Wee (Assistant Professor)

  5. Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore

    Julian Thumboo

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  1. Swee Sung Soon
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  2. Su Yen Goh
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  3. Yong Mong Bee
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  7. Hwee Lin Wee
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Correspondence to Hwee Lin Wee.

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Soon, S.S., Goh, S.Y., Bee, Y.M. et al. Audit of Diabetes-Dependent Quality of Life (ADDQoL) [Chinese version for Singapore] questionnaire. Appl Health Econ Health Policy 8, 239–249 (2010). https://doi.org/10.2165/11313920-000000000-00000

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