History

A 25-year-old man presented to the ED with the chief complaint of low back pain. The pain onset gradually about 10 days prior, days after he lifted some furniture. The pain was described as dull and constant, with an intensity of level 7 out of 10 and getting worse in the past few days. He also had milder pain in the mid-back. Nothing seemed to make the pain better, and movement made the pain somewhat worse. He denied any prior back injury or surgery.

Exam

The physician exam showed the patient to be in moderate discomfort. Triage vital signs entered in the EMR showed BP 130/85, RR 16, P 88, Temp 101.7°F (38.7°C). He had mild to moderate lumbar tenderness; neurologic exam of lower extremities was normal.

Diagnosis and Disposition

The emergency physician diagnosed the patient with “musculoskeletal strain” based on the history of lifting furniture and findings of focal tenderness. He was discharged home on ibuprofen 800 mg tid and instructed to follow up with his primary physician.

The Outcome

The patient returned to the ED 2 days later with increasing back pain and continued fever; he was diagnosed with a spinal epidural abscess at the thoracic and lumbar spinal levels.

The Background on Back Pain

1. Back pain is one of the most common chief complaints presenting to the emergency department, affecting millions of patients and comprising about 2.4% of all ED visits.¹
2. About 0.2% of patients diagnosed with nonspecific back pain return to the ED within 30 days and are admitted for a serious neurologic condition or die in the hospital.²
3. The most common missed condition for patients diagnosed with nonspecific back pain is intraspinal abscess (44% of missed diagnoses).²
4. It is estimated that more than half of patients with spinal epidural abscess are initially misdiagnosed.^3,4
5. The incidence of spinal epidural abscess has doubled over the past decades.

Diagnostic Drivers

Returning to our case of back pain, there were several opportunities to avoid the missed diagnosis of spinal epidural abscess. First, there were several key elements in the history and exam that were either not elicited or simply missed. These key elements are known as diagnostic drivers. The failure to elicit or evaluate these diagnostic drivers is responsible for many, if not most, diagnostic errors.

• IV Drug Abuse. The physician did not evaluate known risk factors for spinal epidural abscess: diabetes, immunocompromised, recent spinal procedure, and IV drug abuse. The patient was an IV drug abuser, but the physician did not ask about this crucial risk factor.
• No discrete mechanism of injury. The pain came on gradually, days after he lifted furniture. There was no discrete mechanism of injury responsible for the pain.
• Multiple levels of pain. The patient complained of pain in the lower and mid-back. Pain at multiple spinal levels is a red flag for spinal epidural abscess.
• Fever by history or exam. The patient had a fever on the initial ED visit, but the physician did not see this EMR entry by the triage nurse. Had the physician realized this patient with back pain was febrile, he would have been more likely to consider the possibility of spinal epidural abscess. The patient continued to have a fever after discharge. The combination of back pain and fever raises the suspicion for a spinal epidural abscess.
• Neurological Exam. The physician documented a “normal” neurological exam. A thorough exam should reflect the consideration of spinal pathology and include documentation of motor strength, sensation, reflexes and gait.

In retrospect, this patient was an IV drug abuser presenting with multiple levels of back pain and fever. These key diagnostic drivers for spinal epidural abscess were not addressed during this seemingly routine evaluation of back pain. The only chance of diagnosing a spinal epidural abscess in the early stages – when there is time to do something about it – is through a careful focused history and exam that takes into consideration the diagnostic drivers for serious causes of back pain.

Beyond the ED Visit: Post-Discharge Check-Ins

For patients with high-risk chief complaints (e.g., back pain, chest pain, abdominal pain, headache) for whom no serious diagnosis is found on the initial visit, there is opportunity to improve diagnostic excellence and patient compliance beyond the point of discharge. A comprehensive Care Coordination program can include periodic communications with the patient regarding the persistence or appearance of “red flag” symptoms and signs.

In the case just discussed, involving the patient in his care after discharge by asking about fever, worsening pain, or neurologic symptoms may have prompted him to return to the ED much earlier. For patients with high-risk, time-sensitive chief complaints, coupling a disciplined clinical process with a program of post-discharge check-ins, both of which routinely consider diagnostic drivers, is the key to improving patient care and avoiding diagnostic error.

References

¹ Rui P, Kang K. National Hospital Ambulatory Medical Care Survey: 2017 emergency department summary tables. National Center for Health Statistics. Available from: https://www.cdc.gov/nchs/data/nhamcs/web_tables/2017_ed_web_tables-508.pdf.

² Dubosh NM, Edlow JA, Goto T, Camargo CA Jr, Hasegawa K. Missed Serious Neurologic Conditions in Emergency Department Patients Discharged With Nonspecific Diagnoses of Headache or Back Pain. Ann Emerg Med. 2019 Oct;74(4):549-561. doi: 10.1016/j.annemergmed.2019.01.020. Epub 2019 Feb 21. PMID: 30797572.

³ Newman-Toker DE, et al. Rate of diagnostic errors and serious misdiagnosis-related harms for major vascular events, infections, and cancers: toward a national incidence estimate using the "Big Three." Diagnosis (Berl). 2020 May 14:/j/dx.ahead-of-print/dx-2019-0104/dx-2019-0104.xml. doi: 10.1515/dx-2019-0104. Epub ahead of print. PMID: 32412440.

⁴ Bhise V, et al. Errors in Diagnosis of Spinal Epidural Abscesses in the Era of Electronic Health Records. Am J Med. 2017 Aug;130(8):975-981. doi: 10.1016/j.amjmed.2017.03.009. Epub 2017 Mar 31. PMID: 28366427.