Age and Disc Degeneration in Low Back Pain: Automated Analysis Enables a Magnetic Resonance Imaging Comparison of Large Cross-Sectional Groups of Symptomatic and Asymptomatic Subjects

Background: Degeneration of the intervertebral disc has long been associated with low back pain even though disc degeneration is seen in people who are asymptomatic. Investigations into the relationship between pain and disc degeneration in symptomatic and asymptomatic subjects are hampered by study sizes, by variations in definition of back pain and differences in MRI annotations of degeneration, study-to-study. Methods: We compared prevalence of disc degeneration between large symptomatic (724) and asymptomatic (701) groups of anonymised female subjects, 30-80yrs. We used SpineNet, a verified automated MRI annotation system to re-annotate MRIs onto the same objective system, irrespective of their original annotation. SpineNet rapidly annotated all MRIs for disc degeneration using the Pfirrmann scale 1-5, and for other degenerative features (herniation, endplate defects, marrow signs, spinal stenosis) as binary present/absent, taking age and spinal level into account. Findings: Severe disc degeneration (Pfirrmann 4 or 5) and degenerative features were significantly more prevalent in symptomatics than in asymptomatics in the lower (L4-S1) but not the upper (L1-L3) lumbar discs, and in subjects <60years. We showed high co-existence of several degenerative features; in both populations c.90% of marrow signs, over all ages and spinal levels, were found in discs which were severely degenerate. We also found 40-50% of the symptomatic population had no MR identified degenerative features up to c. 60 years. Interpretation: The study shows that automated MRI provides a valuable means of rapidly comparing large MRI datasets. Here, it enabled us to detect age and spinal-level related differences in the prevalence of degenerative features between asymptomatic and symptomatic populations. Results also suggest that MRI, by distinguishing between symptomatics whose discs have structural defects, and symptomatics with minimal degenerative changes, could provide a means of clinical stratification, and provide a useful pathway to investigate possible pain sources. Funding: SpineNet: EPSRC Programme Grant Seebibyte (EP/M013774/1) Genodisc: EC FP7 project GENODISC (HEALTH-F2-2008-201626). TwinsUK: Funded by the Wellcome Trust; European Community's Seventh Framework Programme (FP7/2007-2013). OSCLMRIC: Funded by Back-to-Back Charity (1079089). Declaration of Interest: None declared. Ethical Approval: Approval received from NRES Committee South Central - Portsmouth, reference: 09/H0501/95, and from St. Thomas' Hospital Research Ethics Committee (EC95/041). Patient consent was obtained according to the terms of the ethics committee approvals.