O001. Juvenile-onset spondyloarthritis: a study of 54 cases in Senegal
Authors: Sabounji Mounib M , Ndiaye Aïssatou , Niasse Moustapha , Abba Abbasse , Gueye Aminata , Diallo Saïdou 
Published: November 2021

Abstract

Background
Juvenile onset spondyloarthritis (JoSpA), also known as enthesitis-related arthritis (ERA), accounts for approximately 10-20% of all juvenile idiopathic arthritis (JIA) and affects four times more boys than girls. It’s characterized by frequent arthritis of the lower limbs and strongly associated with presence of HLA-B27. In sub-Saharan Africa, SpA is considered as a rare disease where the frequency of HLA-B27 is &lt; 1% in the population. However, an interesting exception is found in the Fula ethnic group of Gambia, where the prevalence of HLA-B27 was estimated at 6% to 7.8%. This ethnic group is also present in Senegal Aims: To determine the epidemiological, clinical, Para clinical, therapeutic and disease course aspects of JoSpA in Senegal.

Methods
A retrospective observational study, was conducted in rheumatology department of Aristide Le Dantec Hospital, between January 2012 and December 2020. Two hundred and fifteen JIA cases were collated, 54 were JoSpA fulfilling the ILAR classification criteria of ERA, with age of onset of symptoms ≤ 16 years. Exclusion criteria were: psoriasis or history of psoriasis, presence of rheumatoid factor and presence of systemic arthritis. Disease activity was assessed by activity indexes (BASDAI and ASDAS), functional impact by BASFI, and Quality of Life by Nottingham Health Profile (NHP).

Results
A total of 54 patients (29 males and 25 females with a sex ratio M/F of 1.16) were included in the study. The mean age at onset of symptoms was 12.4 years, mean age at diagnosis was 23.2 years. 34 (63%) patients were of Fula ethnicity. The inaugural symptomatology was exclusively peripheral in 33 cases (61.1%), axial and peripheral in 23 cases (42.6%). At the time of diagnosis, arthritis was located in the lower limbs in 92.1% of cases, where knee involvement was predominant in 30 (55.6%) cases, followed by hip involvement in 17 (31.5%) cases. Axial involvement was present in 46 cases (85.2%), dominated by sacroiliac pain/ buttock pain in 73.9%, followed by low back pain in 52.1%. Entheseal involvement was present in 30 cases, dominated by Achilles enthesitis and plantar fasciitis in 83.3%. Involvement of the anterior chest wall was found in 12 patients. Uveitis was present in 3 patients. Biological inflammatory syndrome was found in 55.5% of cases, with a mean CRP level of 17.1mg/l. Search for HLA-B27 was carried out in 34 patients, 25 were HLA-B27 positive (73.5%). Among HLA-B27 positive patients, 21 (84%) were of Fula ethnicity. On radiography, sacroiliitis was present in 29 patients, and 8 had coxitis. On admission, the mean BASDAI and ASDAS-CRP were 4.66/10 and 2.98 respectively, mean BASFI was 4.36/10. NHP showed impairment of all items, especially the concepts of energy, pain, sleep and physical mobility. Treatment was based on: NSAIDs (42 patients, 79.6%), methotrexate (30 patients, 55.5%), sulfasalazine (8 patients, 14.8%), oral steroids (15 patients, 27.7%), intra-articular joint steroid injections (6 patients), hip replacement surgery (2 patients), and functional rehabilitation (5 patients). The evolution was favorable, after 6 months of treatment, mean BASDAI and BASFI were 2.47/10 and 2.19/10 respectively.

Conclusion
In our study, JoSpA affects both girls and boys. The prevalence of HLA-B27 was 73.5% of cases, especially in the Fula ethnic group. The disease is considered as a source of significant functional impact and impairment of quality of life. The treatment was based mainly on conventional treatment. Evolution was globally favorable after treatment. Further epidemiological studies are needed to obtain reliable prevalence rates and to better understand our findings.