Similar biologic drug response regardless of radiographic status in axial spondyloarthritis: data from the BSRBR-AS registry by Michelena, et al. Rheumatology (Oxford). 2021 Jan 27;keab070. doi: 10.1093/rheumatology/keab070.
By Jean Liew, MD
This study uses the BSRBR-AS registry, a UK-based registry of participants with axSpA meeting the ASAS criteria who were starting their first biologic between 2012-2017. The authors compared r-axSpA to nr-axSpA for the following: 1) baseline characteristics; 2) biologic response at one year as measured by ASDAS low disease activity, ASDAS-CII, and ASDAS-MI; and 3) drug survival.
They included 1145 from the registry. At baseline, the r-axSpA group had a higher proportion who were male, were older, and had a longer disease duration. This is expected, based on prior studies. There were no difference between axSpA groups in either of the three outcomes for biologic response at one year. Finally, drug survival was similar between two groups, after adjusting for important confounders (age, sex, baseline ASDAS, HLA-B27 status, smoking status, disease duration, and biologic type), with adjusted HR 0.94 (95% CI 0.69, 1.28) for first biologic discontinuation.
This study provides similar data to a prior study conducted in the Danish registry, DANBIO, which looked at a similar number of participants (n=1250) and also found similar response rates between r-axSpA and nr-axSpA. Another similar study in the Swiss registry, SCQM (n=1090), however, found that r-axSpA particpants had higher response rates (measured by ASAS40) compared to nr-axSpA. Study heterogeneity may be a factor here, especially in terms of which people are able to get biologics, and when, as determined by country-specific factors.
Limitations of the current study included use of a complete case analysis for the outcome of biologic response at one year. As there were many missing follow-up ASDAS values, this cut the study sample down to 290. However, the authors were able to use most of the study sample for survival analysis assessing biologic response. They did not note that any imputation needed to be done for this last analysis.
Comparison of an online self-referral tool with a physician-based referral strategy for early recognition of patients with a high probability of Axial SpA by Proft et al (Semin Arthritis Rheum, Oct 2020)
By Delamo Bekele, MD
This study explores an important question of finding ways to reduce the incredibly long diagnostic delay in patients with axial SpA. The study was conducted at the Spondyloarthritis clinic of the Charite Hospital in Berlin, Germany. The authors compared two groups:
(1) Physician referred patients using the Berlin referral tool: performed by Orthopedics and Primary Care Physicians requiring: chronic back pain for > 3 months, back pain onset < 45 years and at least one of the following three parameters: inflammatory back pain, HLA B27 positivity and sacroiliitis on imaging (radiographs or MRI).
(2) Self referred patients using an online tool developed based on the Assessment in SpondyloArthritis international Society (ASAS) referral recommendations chronic back pain for > 3 months, back pain onset < 45 years and one out of 13 parameters (inflammatory back pain features or other clinical or serologic parameters indicative of SpA).
Over a 12 month period, 361 patients who met the study criteria was evaluated (180 via the online self-referral tool and 181 via the physician referral tool). 35 (19.4%) of the self-referred and 71 (39.2%) in the physician-referred group were finally diagnosed with ax SpA. The online self-referred group was more likely HLA-B27 negative, female sex and non-radiographic (12.8% versus 6.7%).
The strength of this study is providing data on an alternate/additional referral system which can address delays due to access, and lack of . A positivity rate of 19% eclipses the estimated prevalence of SpA (0.5-1.5%) and assumed prevalence of 5% in patients with chronic back pain. Further studies replicating these findings and in different populations are needed before it could be implemented into clinical practice. Consideration of more rigid entry criteria (2 or more parameters) for online referral patients may increase the utility. A limitation was the lack of evaluation of individual who filled out the online tool and did not meet study criteria. Application of similar online tools may not be as feasible in areas with lower socio-economic status and advanced education.
