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Validity and reliability of the Gout Impact Scale in a multi‐ethnic Asian population
Author(s) -
Lee Weixian,
Teng Gim Gee,
Kok Joon Chong,
Santosa Amelia,
Lim Anita Y. N.,
Wee HweeLin
Publication year - 2019
Publication title -
international journal of rheumatic diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 41
eISSN - 1756-185X
pISSN - 1756-1841
DOI - 10.1111/1756-185x.13595
Subject(s) - medicine , confirmatory factor analysis , scale (ratio) , clinical psychology , population , psychosocial , ethnic group , anxiety , reliability (semiconductor) , demography , gerontology , structural equation modeling , statistics , psychiatry , environmental health , cartography , mathematics , geography , power (physics) , physics , quantum mechanics , sociology , anthropology
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.