To understand Chinese AS patients, reading this article is enough!

*For medical professional reading reference only

Spondyloarthritis (SpA) is a diverse group of interrelated inflammatory arthritis with diverse clinical features and common genetic susceptibility, histopathology, and etiology

Among them, ankylosing spondylitis (AS) is considered to be the most typical subtype of SpA.

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The incidence of AS was 5.

The global incidence of AS fluctuates widely, and the Han population in northern China is at a low-to-medium level (however, since China has 56 ethnic groups, a multicenter, multi-ethnic epidemiological survey is currently lacking to fully elaborate)

Looking back at the AS epidemiological surveys conducted in China over the past 15 years, the results are as follows:

• Seven cross-sectional studies based on community population (n=55959) showed that the prevalence of AS in community population was 0.

  
  

• A comparison of two non-overlapping meta-analyses showed that the prevalence of AS was higher in China from 2005 to 2019 than from 1994 to 2006 (0.

  
  

In contrast, the prevalence of AS ranges from 0.
20% to 0.
55% in the United States, 0.
25% in Europe, 0.
02% in Africa, 0.
11% in the Middle East, 0.
16% in East Asia, 0.
07% in Southeast Asia, and 0.
07% in South Asia was 0.
06%
.

The male-to-female ratio of AS prevalence in mainland China was 2.
8:1 (0.
42%:0.
15%), which was slightly higher than the global AS prevalence [2.
58:1 (0.
31%:0.
12%)]
.

It can be seen that the prevalence of AS is higher than before, and compared with women, the risk of AS in the male group is obviously higher
.

In addition, men with AS were significantly younger than women at onset and diagnosis, and had higher rates of CRP, erythrocyte sedimentation rate, acute anterior uveitis (AAU), HBV infection, and osteoporosis
.

The overall prevalence of HLA-B27 varies significantly worldwide
.

The prevalence of HLA-B27 in the Han population was between 3.
6% and 5.
7%, lower than the 8% reported in Europe
.

Two large-scale multicenter studies conducted a statistical analysis of the prevalence of HLA-B27 in Chinese AS patients, and the results showed that 88.
8%-89.
4% of Chinese AS patients were HLA-B27 positive
.

Among AS patients in Korea, Europe, Canada, and Latin America, the prevalence of HLA-B27 was 94.
8%, 83%, 79%, and 71%, respectively
.

The average age of onset in Chinese AS patients was 29.
2 years
.

The age of AS onset in HLA-B27 carriers was lower than that in non-HLA-B27 carriers (26.
2±9.
45 vs 31.
3±12.
3), the duration of AS (5 years vs 3 years) and the prevalence of family history (24.
3%) in HLA-B27 carriers vs 11.
5%) higher than non-HLA-B27 carriers
.

For extra-articular manifestations, HLA-B27 patients had a lower prevalence of psoriasis (0.
7% vs 2.
5%) and a higher prevalence of uveitis (11.
2% vs 5.
1%)
.

HLA-B27 typing showed that the incidence of uveitis was associated with HLAB*2704 and HLA-B*2705 subtypes
.

Furthermore, HLA-B27 patients exhibited higher disease activity as measured by CRP and ASDAS-CRP
.

The etiology of AS is unknown, but in addition to genetic risk factors (including HLA-B27), environmental factors (eg, geographic location, lifestyle, gut microbial dysbiosis, infection, and physical activity) have also been implicated in the pathogenesis of AS
.

A two-center cross-sectional study (n=807) compared the clinical characteristics of AS patients in northern and southern China, and based on their place of origin, and found that the proportion of patients with peripheral joint disease in the northern group was significantly higher than that in the southern group, while the proportion of patients with axial joint disease was significantly higher in the northern group than in the southern group.
The proportion of patients showed the opposite result
.

The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI) were reported to be significantly higher in smokers than in non-smokers
.

Because smoking patients have a longer disease course, higher disease activity index, poorer disease function index, higher inflammatory index, and increased MRI inflammatory manifestations
.

A study analyzing the stool of untreated AS patients (n=85) showed increased oxidative phosphorylation, lipopolysaccharide biosynthesis, and glycosaminoglycan degradation
.

Common features associated with autoimmunity, such as Bacteroides fragilis and type III secretion systems (T3Ss), were also found in the AS gut microbiota, suggesting a perturbed gut microbiota in untreated AS patients
.

A large community-based cohort study (n=121,656) demonstrated that baseline hs-CRP was positively associated with risk of future AS, and suggested that CRP plasma concentrations may predict future risk of AS in the Chinese population
.

In addition, it was also found that adherence to physical activity (>80 min/week) may reduce the risk of developing AS
.

As in other countries, the most common clinical manifestations of AS patients in China are low back pain and stiffness
.

In one cohort study (n=449), patients with a longer disease course were more likely to present with thoracic spine involvement early in the disease course
.

Second, among AS patients in China, the hip joint is the most prone to disability
.

33.
9% of patients with AS (n=4875) had current or previous peripheral arthritis, 29.
7% had peripheral arthritis swelling, 66.
2% had enthesitis, and 22.
7% had current or past heel pain symptoms
.

Uveitis is the most common extra-articular manifestation of AS
.

The prevalence of AAU in AS patients in China was 9.
7%-16.
2%, which was lower than 23% in the United States and 25.
8%-32.
7% in Europe
.

At the same time, uveitis has also been confirmed by many studies to be closely related to the course of AS and other manifestations
.

The three studies together showed that the mean disease duration in the uveitis group was longer than that in the non-uveitis group (7.
84±7.
45 years vs 4.
14±4.
43 years), and the percentage of peripheral joint involvement in the uveitis group (51.
4%-77.
8%) was higher than that in the non-uveitis group.
Uveitis group (32.
5%~47.
6%)
.

In the process of disease diagnosis and treatment, patient self-management is very important
.

Exercise therapy is an important intervention to improve the function and quality of life of patients with AS, and several studies have confirmed the effectiveness of exercise therapy on AS
.