Figure 1: 7MM, age-standardized diagnosed prevalence of ankylosing spondylitis
Ankylosing spondylitis and psoriatic arthritis are part of a disease family called spondyloarthropathies (SpAs), which includes debilitating chronic inflammatory joint diseases. Although the diseases have relatively low prevalence, GlobalData’s primary market research in the seven major markets (US, 5EU [France, Germany, Italy, Spain, and UK] and Japan) indicates that we should expect a significant increase in the diagnosis rate of ankylosing spondylitis and psoriatic arthritis in the next 10 years, resulting in increases in the patient population for both diseases (the annual growth rate for diagnosed prevalent cases of ankylosing spondylitis is 7.44%, for psoriatic arthritis is 4.56%). Understanding the disease characteristics and prevalence trends across the major pharmaceutical markets will be imperative in preparing for the increase in the size of the patient population.
SpAs mainly affect the sacroiliac joint, the attachment between lower back and pelvis, thus resulting in pain in the lower back, hips or shoulders, stiffness in the joints in the mornings, and swollen joints. SpAs can be easily misdiagnosed, as the symptoms are not specific to SpAs and can be similar to other diseases such as rheumatoid arthritis and gout. There are also numerous diagnostic criteria available for SpAs, thus making epidemiological studies and comparisons across populations difficult.
The cause of SpA is unknown; however, the presence of a specific gene, HLA-B27, is frequently associated with developing SpA. About 80% of SpA patients have HLA-B27 positivity. In fact, the prevalence of SpA mirrors closely the prevalence of the HLA-B27 gene. The prevalence of the HLA-B27 gene in Caucasian populations is approximately 10%, while in Japanese patients it is only approximately 1%. It is therefore expected that ankylosing spondylitis and psoriatic arthritis would be more prevalent in Caucasian populations than Japanese populations.
GlobalData epidemiologists conducted a thorough literature review on the prevalence of the two major SpAs, ankylosing spondylitis and psoriatic arthritis, and confirmed the expected geographical variations in disease prevalence. The figures above and below present the age-standardized diagnosed prevalence of ankylosing spondylitis and psoriatic arthritis. For ankylosing spondylitis, US men have the highest prevalence at 0.31%, whereas Japanese men and women have the lowest prevalence, at 0.01%. For psoriatic arthritis, men in Spain and Italy have the highest prevalence at 0.20%, whereas men and women in Japan have the lowest, at 0.01%. This data reflects the fact that Japan only constitutes about 1% of the patient population in the 7MM, whereas the US constitutes 40–50%.
Figure 2: 7MM, age-standardized diagnosed prevalence rate of psoriatic arthritis
For more information and detailed epidemiology forecast of ankylosing spondylitis and psoriatic arthritis, please see the EpiCast reports and models.
GlobalData (2015). EpiCast Report: Ankylosing Spondylitis – Epidemiology Forecast to 2024, July 2015, GDHCER56-15
GlobalData (2016). EpiCast Report: Psoriatic Arthritis – Epidemiology Forecast to 2025, December 2016, GDHCER134-16