Validity and reliability of the Assessment of Spondyloarthritis International Society Health Index in English‐speaking patients with axial spondyloarthritis in Singapore

Abstract

Objectives To assess the validity and reliability of the Assessment of Spondyloarthritis International Society Health Index (ASAS HI) among patients with axial spondyloarthritis (axSpA) in Singapore. Methods We collected data from English‐speaking patients with axSpA seen at a dedicated axSpA clinic in a Singapore tertiary referral hospital from 2017 to 2018. Face validity of the English version of ASAS HI was assessed through cognitive debriefing interviews (CDIs). Structural validity was assessed with confirmatory factor analysis. Convergent construct validity was assessed with 12 a priori hypotheses about the magnitude and direction of correlations between the ASAS HI summary score and other patient‐reported outcome measures. Internal consistency was assessed using Cronbach's alpha. Test‐retest reliability was assessed by intraclass correlation coefficient (ICC). Measurement error was assessed by analyzing smallest detectable change (SDC). Results Ten patients (age range 22‐46 years, 50% male) participated in CDIs and face validity was supported. Among 108 patients (median age: 37 [21‐77], 80.6% males), unidimensionality was confirmed (comparative fit index = 0.960, Tucker‐Lewis Index = 0.952, root mean square error of approximation = 0.038, standardized root mean residuals = 0.068, model Chi‐square test P = 0.1251) in the 17‐item ASAS HI. The ASAS HI showed good internal consistency of 0.83 and excellent test‐retest reliability (ICC = 0.95; 95% CI 0.91‐0.98) when baseline was compared with week 2. SDC was 1.02. Convergent validity was supported as hypotheses were confirmed in 100% of the results. Conclusions This study supports the ASAS HI as a valid and reliable measure of health status for use in patients with axSpA in Singapore.

ASAS Health Index as an Addition to Routine Clinical Practice

“…With its multidimensional structure, the ASAS HI has the ability to identify not only aspects clearly related to the disease (e.g., pain) but also other more patient-dependent aspects (e.g., feelings of frustration). It is logical to expect some concordance between the ASAS HI and other more standard assessment measures of SpA (construct validity), as we and others have verified 4,5,6,7,8 , but this does not point, in any way, to interchangeability between these measures. In the Kiltz, et al editorial, the authors state that in our study, we argued in favor of the use of ASAS HI to evaluate disease activity, thus replacing more conventional tools such as ASDAS or BASDAI in this task 1,4 .…”

Test–retest reliability of outcome measures: data from three trials in radiographic and non-radiographic axial spondyloarthritis

“…Information available from the literature regarding reliability of the instruments included in the current study is presented in table 1. [23][24][25][26][27][28][29][30][31][32][33][34][35][36] Detailed results from all trials and subgroups are provided in tables 1 and 2. In the text, reliability per domain is described only for the total axSpA group in the COAST datasets, as these included most instruments.…”

Protocol for a randomized controlled trial of electroacupuncture in the management of patients with axial spondyloarthritis in Singapore (E‐AcuSpA)

“…The outcome measures selected were guided by the endorsed ASAS/Outcome Measures in Rheumatology (OMERACT core sets 29 . All PROMs used have been validated across various countries, including Singapore 30–41 . We have selected week 3 as the first time‐point as it would be after the first five sessions of acupuncture.…”

“…29 All PROMs used have been validated across various countries, including Singapore. [30][31][32][33][34][35][36][37][38][39][40][41] We have selected week 3 as the first time-point as it would be after the first five sessions of acupuncture. Pain-relieving effects of electroacupuncture are expected to be faster than manual acupuncture and would be more evident at this point.…”