TY - JOUR
T1 - Development and validation of an alternative ankylosing spondylitis disease activity score when patient global assessment is unavailable
AU - Ortolan, Augusta
AU - Ramiro, Sofia
AU - van Gaalen, Floris
AU - Kvien, Tore K.
AU - Landewe, Robert B. M.
AU - Machado, Pedro M.
AU - Ruyssen-Witrand, Adeline
AU - van Tubergen, Astrid
AU - Bastiaenen, Caroline
AU - van der Heijde, D. sirée
N1 - Publisher Copyright: © 2020 The Author(s). Published by Oxford University Press on behalf of the British Society for Rheumatology. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/2/1
Y1 - 2021/2/1
N2 - OBJECTIVE: To develop an alternative Ankylosing Spondylitis Disease Activity Score (ASDAS) to be used in research settings in axial SpA (axSpA) when Patient Global Assessment (PGA) is unavailable in databases. METHODS: Longitudinal data from four axSpA cohorts and two randomized controlled trials were combined. Observations were randomly split in a development (N = 1026) and a validation cohort (N = 1059). Substitutes of PGA by BASDAI total score, single or combined individual BASDAI questions, and a constant value, were established in the development cohort. Conversion factors for each substitute were defined by Generalized Estimating Equations, obtaining seven 'alternative' formulae. Validation was performed in the validation cohort according to the OMERACT filter, taking into consideration: (i) truth (agreement with original-ASDAS in the continuous score, by intraclass correlation coefficient and in disease activity states, by weighted kappa); (ii) discrimination [standardized mean difference of ASDAS scores between high/low disease activity states defined by external anchors, e.g. Patient Acceptable Symptom State; agreement (kappa) in the percentage of patients reaching ASDAS improvement criteria according to alternative vs original formulae]; and (iii) feasibility. RESULTS: Comparing various options, alternative-ASDAS using BASDAI total as PGA replacement proved to be: truthful (intraclass correlation coefficient = 0.98, kappa = 0.90), discriminative [ASDAS scores between Patient Acceptable Symptom State no/yes: standardized mean difference = 1.37 (original-ASDAS standardized mean difference = 1.43); agreement with original-ASDAS in major improvement/clinically important improvement criteria: kappa = 0.93/0.88] and feasible (BASDAI total often available, as questions required for the ASDAS; conversion coefficient ≈ 1). CONCLUSION: Alternative-ASDAS using BASDAI total score as PGA replacement is the most truthful, discriminative and feasible instrument.
AB - OBJECTIVE: To develop an alternative Ankylosing Spondylitis Disease Activity Score (ASDAS) to be used in research settings in axial SpA (axSpA) when Patient Global Assessment (PGA) is unavailable in databases. METHODS: Longitudinal data from four axSpA cohorts and two randomized controlled trials were combined. Observations were randomly split in a development (N = 1026) and a validation cohort (N = 1059). Substitutes of PGA by BASDAI total score, single or combined individual BASDAI questions, and a constant value, were established in the development cohort. Conversion factors for each substitute were defined by Generalized Estimating Equations, obtaining seven 'alternative' formulae. Validation was performed in the validation cohort according to the OMERACT filter, taking into consideration: (i) truth (agreement with original-ASDAS in the continuous score, by intraclass correlation coefficient and in disease activity states, by weighted kappa); (ii) discrimination [standardized mean difference of ASDAS scores between high/low disease activity states defined by external anchors, e.g. Patient Acceptable Symptom State; agreement (kappa) in the percentage of patients reaching ASDAS improvement criteria according to alternative vs original formulae]; and (iii) feasibility. RESULTS: Comparing various options, alternative-ASDAS using BASDAI total as PGA replacement proved to be: truthful (intraclass correlation coefficient = 0.98, kappa = 0.90), discriminative [ASDAS scores between Patient Acceptable Symptom State no/yes: standardized mean difference = 1.37 (original-ASDAS standardized mean difference = 1.43); agreement with original-ASDAS in major improvement/clinically important improvement criteria: kappa = 0.93/0.88] and feasible (BASDAI total often available, as questions required for the ASDAS; conversion coefficient ≈ 1). CONCLUSION: Alternative-ASDAS using BASDAI total score as PGA replacement is the most truthful, discriminative and feasible instrument.
KW - axial spondyloarthrits
KW - disease activity
KW - patient-reported outcomes
KW - validation
UR - http://www.scopus.com/inward/record.url?scp=85102212523&partnerID=8YFLogxK
U2 - https://doi.org/10.1093/rheumatology/keaa241
DO - https://doi.org/10.1093/rheumatology/keaa241
M3 - Article
C2 - 32572483
SN - 1462-0324
VL - 60
SP - 638
EP - 648
JO - Rheumatology (Oxford, England)
JF - Rheumatology (Oxford, England)
IS - 2
ER -