The efficacy of treatment in Axial Spondyloarthritis (SpA) can be influenced by several factors, such as gender, age at the start of treatment and disease duration. Most data on factors that influence the efficacy of TNF inhibitors are available of ankylosing spondylitis (AS) and some on non-radiographic axial SpA (nr-ax SpA).
Gender differences have shown to be very relevant in the prediction of response as well as on drug survival. In general, most studies describe that females have higher disease activity (BASDAI), a higher age at diagnosis, more enthesitis and worse function (BASFI), but that males have more radiographic changes and a higher radiographic progression rate. There are controversial data on the gender differences associated with raised CRP or ESR levels.
Response to NSAID's was shown to be higher in young patients with a short disease duration. These factors also play an important role in the predictors of a good response to TNF blockers: young age and a short duration of symptoms (less than 10 years), as well as high disease activity parameters (BASDAI, raised CRP), presence of the HLA-B27 antigen and a better function (lower BASFI)1.
Drug survival on anti-TNF treatment in AS is also influenced by gender. Females switch more often between TNF blocking agents compared to males and show lower responsiveness2.
In non-radiographic axial SpA, studies show that response rates and drug survival were higher in HLA-B27 positive patients, younger patients, in case of raised CRP and low BASFI scores whereas others found an association between inflammatory MRI-sacroiliitis and male sex3.
Less data are available of radiographic changes as an efficacy parameter of anti-TNF treatment. In most clinical trails with TNF blockers ankylosed patients were excluded but there is evidence that these patients also benefit from this treatment. In several short term follow up studies radiographic progression was not delayed by anti-TNF treatment but a longer, four year follow up study showed a significant reduction in the chance of radiographic progression4. This radiographic progression was also influenced by baseline damage and smoking but not by gender differences.
In conclusion, patients with axial SpA, show higher responsiveness to anti-TNF treatment at a younger age with a short disease duration and higher disease activity parameters, such as BASDAI and CRP. Females have a lower response to anti-TNF compared with males and switch more often to another TNF blocker.
Vastesaeger N, et al. Predicting the outcome of ankylosing spondylitis therapy. Ann Rheum Dis. 2011 Jun;70(6):973-81
van der Horst-Bruinsma IE, et al. Female patients with ankylosing spondylitis: analysis of the impact of gender across treatment studies. Ann Rheum Dis. 2013; 72 (7):1221-4
Gulfe A, et al.Efficacy and drug survival of anti-tumour necrosis factor-alpha therapies in patients with non-radiographic axial spondyloarthritis: an observational cohort study from Southern Sweden. Scand J Rheumatol. 2014;43(6):493-7.
Haroon N, et al. The impact of tumor necrosis factor α inhibitors on radiographic progression in ankylosing spondylitis. Arthritis Rheum. 2013 Oct;65(10):2645-54
Disclosure of Interest None declared