AB0942 Concordance between fatigue, pain and patient global assessment in individual patients with psoriatic arthritis
Authors: O. Rintek Madsen
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Associations between fatigue (FTG), pain and patient global assessment (PaGl) have been examined on the group level in patients with psoriatic arthritis (PsA), but studies focusing on the concordance between these patient-reported outcome measures (PROMs) in individual patients are missing. A better understanding of how tight the measures are bounded in individuals may improve our ability to deal with them in the daily clinic. <h3>Objectives</h3> To examine associations on the group level and concordance on the individual patient level between FTG, pain and PaGl as scored on 0–100 visual analogue scales (VAS) in the daily clinic by patients with PsA. The influence of other clinical disease activity measures on these measures was also examined. <h3>Methods</h3> Data on 132 outclinic PSA patients treated with biological agents were extracted from the Danish registry for biological treatment in rheumatology (DANBIO). Data comprised VAS FTG, pain, PaGl and physician global assessment (PhGl), and HAQ-DI, swollen and tender joint counts (66/68), CRP, DAS28-CRP and age. Simple linear regression analyses were used to assess the association between FTG, pain and PaGl. Independent predictors of FTG, pain and PaGl were identified using stepwise multiple regression analysis. Degrees of association were expressed by coefficients of correlation, beta-values and standard errors of estimation (SEE). Concordance between FTG, pain and PaGl on the individual patient level was examined using the Bland-Altman method yielding 95% lower and upper limits of agreement (LLoA and ULoA) and corresponding biases (mean of intra-individual differences). <h3>Results</h3> Mean age was 54±13 years, mean DAS28 3.7±1.5 and mean PaGl 56±28. FTG, pain and PaGl were strongly inter-associated but errors of estimation were substantial (r-range 0.80–0.94, p&lt;0.0001, SEE-range 11.5–16.9). FTG, pain and PaGl were only poorly correlated with objective measures of disease activity (for example, r-range for swollen joint count 0.19–0.25, p&lt;0.05). FTG was independently predicted (beta, p-value) by PaGl (0.51,&lt;0.001) and pain (0.31,&lt;0.05) (R<sup>2=</sup>0.66, p&lt;0.05, SEE=16.7), pain by PaGl (0.82,&lt;0.0001) and HAQ-DI (0.15,&lt;0.005) (R<sup>2</sup>=0.88, p&lt;0.005, SEE=10.5) and PaGl by pain (0.80,&lt;0.0001) and fatigue (0.17,&lt;0.001) (R<sup>2</sup>=0.89, p&lt;0.001, SEE=12.4). Swollen and tender joint count, CRP and PhGl did not add to the explanation of the patient-reported VAS scores. The bias [LLoA; ULoA] for FTG versus pain was 8.5±19.1 (p&lt;0.0001) [−29.1; 45.9], for FTG versus PaGl 4.1±19.4 (p&lt;0.05) [−34.0; 42.2] and for PaGl versus pain 4.4±11.5 (p&lt;0.0001) [−18.1; 26.9]. Thus biases were small but limits of agreement were pronounced. <h3>Conclusions</h3> In patients with PsA, VAS FTG, pain and PaGl were nearly identical and were strongly inter-associated on the group level with no explanatory influence of more objective measures. However, on the individual patient level substantial discrepancies between the VAS scores were observed. The findings emphasise the complexity of understanding and dealing with PROMs in the daily clinic. <h3>Disclosure of Interest</h3> None declared