Table 1.

Classification criteria of IBP versus MBP from various mechanical and nonmechanical causes

IBP (according to ASAS experts’ criteria, axSpA) [60]

MBP (injury to or derangement of spine structures or rheumatologic, vascular, gastrointestinal, renal, infectious, or oncologic causes) [27, 48]

ASAS criteria: when patient presents with back pain of ≥ 3 months in duration  • Age at onset < 40 years  • Insidious onset  • Improvement with exercise  • No improvement with rest  • Pain at night (with improvement upon getting up) Diagnoses are made by combining clinical criteria with radiological findings (MRI, CT, ultrasound) and/or laboratory test results (e.g., testing for HLA-B27)

Identification of symptoms (no clear evidence about which are clinically relevant)  • Onset at any age; may be more common in middle-aged, working individuals  • Variable onset; may be acute  • Pain may worsen with movement  • Pain often improves with rest Physical examination involving patient history, such as an acute injury  • This process can involve ruling out IBP along with other causes of back pain (e.g., malignancies, infection) Injury or derangement of an anatomical structure in the lower back  • Soft tissue (lumbar sprain or strain)  • Muscle/fascia (myofascial pain)  • Disks (herniated disk, discogenic pain)  • Joints (zygapophysial joint and sacroiliac joint pain)  • Bone (vertebral fractures, spondylolisthesis, kyphosis, scoliosis) MBP persisting for > 4 to 6 weeks may warrant further diagnostic testing and imaging

ASAS Assessment of SpondyloArthritis international Society, axSpA axial spondyloarthritis, CT computed tomography, IBP inflammatory back pain, MBP mechanical back pain, MRI magnetic resonance imaging