Background Spondyloarthritis (SpA) comprises a heterogeneous group of diseases sharing several clinical, biochemical and radiological features. Biomarkers for SpA are scarce and their validation in real practice is essential in predicting radiologic progression or establishing personalized therapies. In previous studies we have reported that serum VIP levels could be useful as a prognostic biomarker in early RA (1).
Objectives To analyse the potential correlation between VIP serum levels and disease activity/severity in patients with early SpA.
Methods Longitudinal prospective study of 2 years follow-up of all patients under 45 years of age with inflammatory back pain, more than 3 months and less than two years onset, referred to our early SpA Unit. Register protocol included 3 scheduled visits (baseline, 1, 2 years) for demographic, clinical, laboratory, imaging and serum sample collection. Therapy was also recorded. Clinical data included – Spa features and specific metrology parameters (BASDAI, BASFI), laboratory parameters [HLA-B27, CRP, ESR, alkaline phosphatase (ALP) and haemoglobin (Hb)] and imaging studies [X-Rays and/or sacroiliac joint MRI (ASAS/OMERACT criteria)]. VIP levels were measured by enzyme immunoassay in serum samples from 162 visits. To assess the association of independent variables with serum VIP levels, we performed a longitudinal multivariate analysis, nested by patient and visit, using the command xtgee of Stata 12 for Windows (StataCorp LP, College Station, TX, USA)
Results A total of 54 patients were included. After two years of follow-up, 37 patients (67%) were diagnosed of SpA. The mean age of the entire cohort was 37.5±10.6 years and 61.1% were women. Those patients diagnosed of SpA showed higher frequency of familiar history of Spa (38,9% vs 5,6%), higher prevalence of HLA-B27 positivity (58,3% vs 16,7%), more frequent inflammatory or structural damage findings in the imaging in the sacroiliac joint (58,8% vs 11,1% and 33,3% vs 0%, respectively) than patients without definite diagnosis. Additionally lowers levels of Hb were observed in SpA patients. No significant differences were detected in the others studied variables.
The multivariate analysis showed that those patients with lower levels of VIP displayed significantly higher BASFI score (p=0,003), presence of bone edema in MRI (p=0,006) and lower Hb levels (p=0,013). In addition, coexistence of cutaneous psoriasis was also independently associated with lower levels of VIP in serum (p=0.013) and a similar trend was observed for enthesitis (p=0.068). Finally, we observed that treatment with TNF-blockers seems to increase VIP serum level, although no statistical significance was achieved (p>0.1) likely due to the small number of patients under this therapy
Conclusions Patients with SpA and low serum levels of VIP showed worse 2-year disease outcomes in terms of functional status and inflammation in MRI. Extended patient sample or follow-up could confirm this promising data
Martinez C, Ortiz A M, Juarranz Y, et al. Serum levels of vasoactive intestinal Peptide as a prognostic marker in early arthritis. PloS one 2014; 9: e85248. doi: 10.1371
Acknowledgements This research has been funded by RETICS program, RD 12/0009 (RIER), PI12/758, PI11/195, PI11/505, from Instituto de Salud Carlos III, S2010/BMD-2350 from Comunidad de Madrid.
Disclosure of Interest : None declared