Validity and reliability of the Gout Impact Scale in a multi-ethnic Asian population.

OBJECTIVES: The emphasis on capturing patient-reported outcomes (PRO) is increasing, but gout-specific PRO are lacking. We evaluated the reliability and validity of the 24-item Gout Impact Scale (GIS) of the Gout Assessment Questionnaire 2.0 (GAQ2.0) in a multi-ethnic Asian population. METHODS: Participants with gout in an academic medical center in Singapore completed the GIS which comprises five scales. Confirmatory factor analyses (CFA) were performed. Known-groups validity, divergent validity and internal consistency were evaluated. RESULTS: We analyzed data of 267 participants (mean [SD] age 52.2 [16.08] years, 92.1% men and 76.0% Chinese). CFA based on the original GIS factor structure had good model fit based on Tucker-Lewis Index (TLI) of 0.946 but not when based on Root Mean Square Error Of Approximation (RMSEA), which was 0.123 (90% CI: 0.116-0.130). Internal consistency of GIS exceeded 0.7 in all except one scale, consistent with previous studies. Hypotheses related to known-groups validity were largely supported. Scores were significantly higher (ie greater impact) for participants reporting at least some problem on the EQ-5D-3L anxiety/ depression item across all GIS scales. Correlations between RAND-36 Physical Functioning (PF) scale and all five scales in the GIS were poor (Spearman rank correlation coefficients: -0.2355 to 0.0426), implying that GIS does not measure impact of gout on physical health. CONCLUSION: The GIS is valid and reliable for assessing gout-specific psychosocial functioning in a multi-ethnic Asian population.

Reliability and Validity of the English-, Chinese- and Malay-Language Versions of the World Health Organization Quality of Life (WHOQOL-BREF) Questionnaire in Singapore

<p><b>INTRODUCTION</b>The World Health Organization Quality of Life (WHOQOL-BREF) questionnaire is a 26-item questionnaire that evaluates 4 domains of quality of life (QoL), namely Physical, Psychological, Social Relationships and Environment. This study aimed to evaluate the validity and reliability of the WHOQOL-BREF among Singapore residents aged 21 and above.</p><p><b>MATERIALS AND METHODS</b>We recruited participants from the general population by using multistage cluster sampling and participants from 2 hospitals by using convenience sampling. Participants completed either English, Chinese or Malay versions of the WHOQOL-BREF and the EuroQoL 5 Dimension 5 Levels (EQ-5D-5L) questionnaires. Confirmatory factor analysis, known-group validity, internal consistency (Cronbach's alpha) and test-retest reliability using the intraclass correlation coefficient (ICC) were performed.</p><p><b>RESULTS</b>Data from 1316 participants were analysed (Chinese: 46.9%, Malay: 41.0% and Indian: 11.7%; 57.5% mean, mean standard deviation [SD, range] age: 51.9 [15.68, 24 to 90] years); 154 participants took part in the retest in various languages (English: 60, Chinese: 49 and Malay: 45). Tucker-Lewis Index (TLI) was 0.919, 0.913 and 0.909 for the English, Chinese and Malay versions, respectively. Cronbach's alpha exceeded 0.7 and ICC exceeded 0.4 for all domains in all language versions.</p><p><b>CONCLUSION</b>The WHOQOL-BREF is valid and reliable for assessing QoL in Singapore. Model fit is reasonable with room for improvement.</p>