Diagnosing Low Back Pain

Introduction to Diagnostic Approach

The American College of Physicians recommends that clinicians conduct a thorough diagnostic triage by asking about pain characteristics, red flags, and psychosocial factors that may influence outcomes in patients with low back pain 1, 2

Clinicians should ask about location of pain, frequency of symptoms, and duration of pain, as well as any history of previous symptoms, treatment, and response to treatment in patients with low back pain 1
For patients with leg pain, clinicians should inquire about typical sciatica symptoms, such as back and leg pain in a typical lumbar nerve root distribution 1
For suspected spinal stenosis, clinicians should ask about pseudoclaudication, such as leg pain with walking or standing relieved by sitting, and whether pain is relieved by sitting 3

Clinicians should screen for cauda equina syndrome by assessing for urinary retention, fecal incontinence, saddle anesthesia, and motor deficits at multiple levels in patients with low back pain 1, 4
Clinicians should screen for malignancy by assessing for history of cancer, unexplained weight loss, failure to improve after 1 month, and age older than 50 years in patients with low back pain 1, 4
Clinicians should screen for spinal infection by assessing for fever, recent infection, intravenous drug use, and immunocompromised status in patients with low back pain 1, 4
Clinicians should screen for vertebral compression fracture by assessing for older age, history of osteoporosis, and steroid use in patients with low back pain 1

For patients with radicular symptoms, clinicians should assess knee strength and reflexes, great toe and foot dorsiflexion strength, foot plantarflexion and ankle reflexes, and distribution of sensory symptoms 1, 3
Clinicians should document any rapidly progressive or severe neurologic deficits, including motor deficits at more than one level in patients with low back pain 1

Clinicians should assess psychosocial factors and emotional distress, as they are stronger predictors of low back pain outcomes than either physical examination findings or severity and duration of pain 3
Clinicians should screen for depression, passive coping strategies, job dissatisfaction, higher disability levels, disputed compensation claims, or somatization, as these may predict poorer outcomes in patients with low back pain 3

Clinicians should categorize patients into one of three diagnostic groups: nonspecific low back pain, back pain potentially associated with radiculopathy or spinal stenosis, or back pain potentially associated with another specific spinal cause 1, 2
Nonspecific low back pain is defined as pain occurring primarily in the back with no signs of a serious underlying condition, spinal stenosis, radiculopathy, or another specific spinal cause 2

Clinicians should avoid routine imaging for nonspecific low back pain, as it does not improve outcomes and may expose patients to unnecessary radiation 3
Clinicians should not delay imaging when red flags are present, and immediate MRI is indicated rather than waiting the usual 4-6 weeks recommended for nonspecific back pain 4
The posttest probability of cancer increases from approximately 0.7% to 9% in patients with a history of cancer presenting with back pain 4