Background/Purpose :Juvenile and adult forms of ankylosing spondylitis (AS) have been shown different in initial symptoms,clinical presentation ,imaging manifestations and prognosis.So,according to the diagnostic criteria of adult ankylosing spondylitis (AAS),it is difficult to diagnose early and treat timely for the Juvenile ankylosing spondylitis(JAS).Meanwhile, the JAS mostly will progress to adulthood, the delayed diagnosis and treatment may seriously affect the prognosis and the quality of life in adulthood, We did this retrospective analysis to compare the similarities and differences between the two phenotypes of AS in southern Chinese Han patients, so as to provide  foundation for the early diagnosis and treatment for JAS.

Methods :Case records of 576 patients diagnosed as AS according to modified New York criteria(1984) were reviewed. All the patients satisfied the ACR classification criteria for AS.They were grouped according to age: those with onset of symptoms before the age of 16 years were classified as JAS, and patients older than 16 at onset were classified as AAS. Data on age at disease onset, initial symptoms, clinical features, uveitis and imaging manifestations were recorded.

Results :

There were 165 patients with JAS and 411 with AAS. The former had higher male preponderance(10.8:1 VS 4.3:1, P<0.01) and more frequent onset with peripheral arthritis(P<0.001), while most AAS with initial symptoms of lumbosacral pain.Peripheral joints involved in JAS include lower extremity joints such as the hip, knee, ankle and heel, followed by the upper limb joints, such as the shoulder, elbow and wrist. Positive family history was present in 28 JAS patients (16.97%) and 84 (28.44%) in JAS(p>0.05).JAS patients also had greater involvement of hip joints than AAS( P<0.001).The incidence of spinal involvement was significantly lower in JAS than that in AAS(P<0.001).Through the x - ray examination,the spinal lesions in JAS were characterized by osteoporosis and blurred articular surface,but in AAS were sclerosis of spine bone,  formation of syndesmophyte and bony bridge, bone loss and osteoporosis. The incidence of anterior uveitis was also comparable: 4.91% (8 patients) in JAS and 11.44%(47 patients) in AAS(P<0.05).BMD T-score at the femoral neck was significantly lower in JAS than that in AAS(p<0.05). In addition,the mean time from onset to final diagnosis was much longer in JAS than in AAS (P < 0.01);for those patients with the onset symptoms of Peripheral joints,the mean time from onset to symptoms of axial joints much longer in JAS than in AAS (P < 0.001).

Conclusion :Gender advantage in JAS was more obvious, and JAS had onset more often with peripheral arthritis than with Spinal symptoms. Hip joint involvement was more common in JAS than AAS. The femoral neck BMD was reduced much seriously in JAS compared with that in AAS, while there was lower incidence of ophthalmia in JAS than AAS, clinicians should focus on the different manifestations in JAS and AAS,so as to make early diagnosis, provide aggressive treatment and prevent complications.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-observation-on-ankylosing-spondylitis-patients-with-different-phenotypes/