1. Wang, R, Crowson, C.S, Wright, K, Ward, M. Clinical Evolution of Patients with New-Onset Inflammatory Back Pain: A Population-based Cohort Study. Arthritis & Rheumatology "Accepted Article"; 2018 doi: 10.1002/art.40460.
2. Weber, U, Jurik, AG, Zejden, A, Larsen, E, Jorgensen, SH, Rufibach, K, Schioldan, C, Schmidt-Olsen, S. Frequency and Anatomic Distibution of Magnetic Resonance Imaging Features in the Sacroiliac Joints of Young Athletes. Arthritis & Rheumatology "Accepted Article"; 2018 doi10.1002/art.40429.
One of the challenges in young adults with low back pain is determining if features of inflammatory back pain(IBP) are related or will progress to spondyloarthritis(SpA).
In a recently accepted article in Arthritis and Rheumatology, Wang, et. al.used the Rochester Epidemiology Project, a longstanding population-based study of residents of Olmstead County, Minnesota, retrospectively to look at long-term outcomes of patients with IBP and determine the prevalence of progression to SpA.
Olmstead County residents who had newly diagnosed IBP from age 16 to 35 years between January 1, 1999 and December 31, 2003 were identified from EMR based records which allowed at least 12 years of follow-up. Initially 5304 patients were identified for back pain. Their medical records were reviewed by rheumatologists and classified as "No IBP","possible IBP" and "definite IBP". 172 patients had "possible IBP" and "definite IBP".On detailed review, 124 patients(2.3% of the cohort; 82 men and 42 women) were identified with new-onset IBP. Using the Callin criteria, Berlin criteria and ASAS criteria for IBP, at the end of follow up, 39 patients with IBP had progressed to SpA including 33 patients with AS based on radiographic sacroilitis and 6 with SpA diagnosed clinically by treating rheumatologists. 58 IBP patients resolved and 15 patients evolved into non-SpA conditions( 9 degenerative disk, 3 fibromyalgia, 2 mechanical back pain and 1 systemic lupus erythematosus).
In this cohort, the probabilities of IBP evolving to SpA at 5, 10, and 15 years were 24%, 30%, and 33% respectively. The most important predictors of progression to SpA were uveitis(5 fold risk), male sex and a family history of SpA. The authors concluded that as a minority of patients with new-onset IBP progress to SpA; the resolution of IBP may explain the difference in the prevalence of IBP (3-6%) and SpA(0.5-1%).
MRI has become a helpful tool in assessing inflammation in the spondyloarthritides. In the March Arthritis and Rheumatology, "Frequency and anatomical distribution of magnetic resonance imaging features in the sacroiliac joints of young athletes" examine young athletes for the frequency and anatomical distribution of sacroilitis as bone marrow edema (BME) has been reported in the sacroiliac joints(SIJ) of 25 % of healthy individuals and mechanical back pain which may help better define sacroilitis in early spondyloarthritis. Weber, et. al, examined semicoronal SIJ MRI scans of 20 hobby runners pre/post running and 22 elite ice-hockey players with 3 blinded readers. 3 blinded readers examined 8 anatomical SIJ regions: upper/lower ilium and sacrum, subdivided in anterior/posterior slices for BME. BME was found most commonly in the posterior lower ilium region and on average in 3-4 SIJ quadrants in the hobby and elite athletes. The reason for the frequency of BME in young healthy active adults is unknown and is theorized to be from mechanical stress and anatomical variations. 30-41% of the athletes had average 5-6 SIJ quadrants affected by BME meeting the ASAS definition for active sacroilitis. SIJ erosions were almost absent from the athletic cohort suggesting high specificity for recognition of early axial SpA.
