Eligibility criteria for biologic disease-modifying antirheumatic drugs in axial spondyloarthritis: going beyond BASDAI

Abstract

ObjectivesTo compare definitions of high disease activity of the Ankylosing Spondylitis Disease Activity Score (ASDAS) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in selecting patients for treatment with biologic disease-modifying antirheumatic drugs (bDMARDs).MethodsPatients from Rheumatic Diseases Portuguese Register (Reuma.pt) with a clinical diagnosis of axial spondyloarthritis (axSpA) were included. Four subgroups (cross-tabulation between ASDAS (≥2.1) and BASDAI (≥4) definitions of high disease activity) were compared regarding baseline characteristics and response to bDMARDs at 3 and 6 months estimated in multivariable regression models.ResultsOf the 594 patients included, the majority (82%) had both BASDAI≥4 and ASDAS ≥2.1. The frequency of ASDAS ≥2.1, if BASDAI<4 was much larger than the opposite (ie, ASDAS <2.1, if BASDAI≥4): 62% vs 0.8%. Compared to patients fulfilling both definitions, those with ASDAS ≥2.1 only were more likely to be male (77% vs 51%), human leucocyte antigen B27 positive (79% vs 65%) and have a higher C reactive protein (2.9 (SD 3.5) vs 2.1 (2.9)). Among bDMARD-treated patients (n=359), responses across subgroups were globally overlapping, except for the most ‘stringent’ outcomes. Patients captured only by ASDAS responded better compared to patients fulfilling both definitions (eg, ASDAS inactive disease at 3 months: 61% vs 25% and at 6 months: 42% vs 25%).ConclusionThe ASDAS definition of high disease activity is more inclusive than the BASDAI definition in selecting patients with axSpA for bDMARD treatment. The additionally ‘captured’ patients respond better and have higher likelihood of predictors thereof. These results support using ASDAS≥2.1 as a criterion for treatment decisions.

Low BASDAI score alone is not a good predictor of anti-tumor necrosis factor treatment efficacy in ankylosing spondylitis: a retrospective cohort study

“…Consistent with our results, one previous study indicated that 36.9% (210/568 patients) of patients with low BASDAI scores (< 4) had high disease activity as measured by the ASDAS-CRP (≥ 2.1) [11]. Moreover, even higher percentages of patients having high ASDAS-CRP (≥ 2.1) among those having low BASDA score (< 4) were shown in two other studies; 62.1% (64/103 patients) and 65.8% (48/73 patients) [12,13].…”

“…One previous study investigating eligibility criteria for initiation of anti-TNF treatment in AS patients showed that an ASDAS-CRP result ≥ 2.1 is associated with a greater likelihood of improvement than a high BASDAI score (≥ 4), but the patients who had both ASDAS-CRP ≥ 2.1 and BASDAI ≥ 4 showed the greatest improvement [12]. Similarly, from another prospective cohort study, applying the ASDAS definition of high disease activity leads to more axial SpA patients being selected to start anti-TNF treatment and these 'captured' patients have a greater likelihood of known predictors of good response to anti-TNF than traditional BASDAI definition (≥ 4) [13]. One study including patients with AS and undifferentiated SpA treated with etanercept or infliximab revealed that the discriminatory ability of the ASDAS outperformed that of the BASDAI, patient global score, ESR, CRP, or acute inflammation score as assessed by MRI [19].…”

The Association Between TNF Inhibitor Therapy Availability and Hospital Admission Rates for Patients with Ankylosing Spondylitis. A Longitudinal Population-Based Study

“…Finally, while not a primary aim of this study but because Australian data are lacking, we used these two datasets to estimate the population prevalence of AS. Based on the assumption that the 1925 AS patients that used a TNFi in 2020 represent 60% of all AS patients [16,17] in WA, the estimated point prevalence for AS was 0.29% in 2020. This figure agreed with the 0.28% period prevalence rate of AS amongst all hospital admissions in WA over 20 years (Suppl Fig.…”

“…Given the lack of efficacy of traditional disease-modifying drugs in AS [ 11 ], the rapid uptake of TNFi following its approval for AS in Australia is not unexpected and in line with early expectations that, depending on national health care systems, 38–78% of AS patients attending rheumatology clinics in Europe would be initiated on TNFi therapy [ 18 ]. Current data suggest that at least 60% of AS patients will be initiating TNFi when following BASDAI-based guidelines, which are also in use in Australia [ 17 ]. This number can be expected to increase in the future as AS patients with BASDAI scores < 4 also have significant reductions in disease activity with TNFi [ 17 ].…”

“…Descriptive statistics were compared by non-parametric methods (Kruskal–Wallis) for continuous variables and by crude odds ratio (OR) with 95% confidence intervals (CI) for categorical data. To reduce confounding, we excluded hospital admissions for TNFi infusions ( n = 10,879 since 2005) and chronic dialysis ( n = 3661) from the admission data which are presented as rate per 100,000 population and compared by rate ratios (RR) with 95% CI derived from conditional maximum likelihood estimates using Poisson distribution [ 17 ]. Direct hospital-based health care costs were based on 2008 costing data provided by the business unit at one of the metropolitan hospitals (personal communication) and adjusted for inflation using the consumer price index (CPI), health expenditure sub-class published by the Australian Bureau of Statistics and expressed in 2020 dollars (average AU$ 2,332/day), ED visits (AU$ 624) and outpatient infusions (AU$ 449).…”