Canada has been experiencing an opioid crisis for years, with over 52,000 deaths reported between 2016 and 20251. The most prevalent harms associated with this crisis are accidental overdoses, but infectious diseases are also a critical consideration for physicians providing care. Some of these diseases, such as skin abscesses, may be relatively straightforward to diagnose when clear symptoms and clinical signs are present. Others, such as infective endocarditis and spinal abscess, can pose a much greater diagnostic challenge.
Case example: Delayed diagnosis of an epidural abscess
A 47-year-old patient presents to a walk-in clinic complaining of thoracic back pain after a recent fall. Her medical history includes frequent visits to the emergency department and therapeutic use of methadone. Findings on physical examination include multiple skin abscesses on her arms and a low-grade fever. The doctor diagnoses a musculoskeletal cause to explain her back pain, prescribes an analgesic, and orders thoraco-lumbar spine X-rays.
The following day, the patient presents to the emergency department of a community hospital with back and abdominal pain. She has a temperature of 39.2°C and her white cell count is 21 x 109/l. The physician prescribes oral ciprofloxacin, documents musculoskeletal pain, and orders repeat blood work. At shift change, care transfers to a second physician who performs an incision and drainage of a lesion on the patient’s arm, and discharges her with a diagnosis of subcutaneous abscess.
The patient returns that evening, staggering, somnolent, and complaining of numbness in both legs. The physician on duty reaches the patient’s family doctor who shares that the patient currently uses intravenous fentanyl. The physician admits the patient and orders blood cultures. Both blood cultures are positive for Staphylococcus aureus. The patient now complains of weakness in her legs and difficulty voiding. The physician orders an urgent MRI, which reveals an epidural abscess with cord compression at T3, and the patient is referred for an urgent laminectomy. The patient is left with paraplegia and launches a legal action.
In their review of the case, peer experts expressed concern about the absence of a documented neurological exam in the emergency department, and were critical of the first physician for a lack of clear differential diagnosis. Criticisms of the care in the first emergency visit focused on a lack of clear follow-up arrangements, inadequate discharge instructions, and poor documentation. CMPA settled on behalf of the physicians.
Diagnostic considerations
Infective endocarditis, discitis, and epidural abscesses are characterized by symptoms that may mimic more common conditions, and are well-known among physicians for being difficult to diagnose. If the patient is using intravenous drugs, diagnosis can be further complicated by social stigma, variability in terms of patient consent, and adherence to treatment and follow-up plans (e.g. being unable to afford medications, poor access to transportation for appointments).
A review of CMPA cases closed between 2015 and 2024 revealed nine medico-legal matters related to diagnostically challenging conditions associated with injecting drug users. Four involved spinal epidural abscess or infective discitis, two involved septic arthritis, two involved infective endocarditis, and one involved bacterial pneumonia. There were eight civil legal cases, four of which ended in a settlement and the other four of which were dismissed by the court.
Diagnostic difficulties resulting from lost situational awareness, complex patient social circumstances, and communication breakdowns were prominent in these cases, and have a particular relevance when treating patients who use intravenous drugs.
Risk management strategies
When managing patients with a history of substance use disorder, be aware of how cognitive biases can narrow diagnostic inquiry, and be on the lookout for indicators of increasingly prevalent rare infections in patients with a history of IDU. Some additional risk management strategies of relevance to the diagnostic challenges observed during this review include:
- Consider the use of structured tools at handover to communicate management plans, including monitoring and risk of deterioration, to facilitate team situational awareness.
- Be aware of repeat presentations to the emergency department and the presence of worsening symptoms that can provide an indicator of a condition that has been overlooked. Biases toward this patient population can also influence diagnostic reasoning. Recognizing these can motivate the caregivers to reconsider the differential diagnosis.
- Consider seeking a collateral history from family members or other care providers when collecting crucial information directly from the patient is not reasonably possible.
The bottom line
The opioid crisis has been associated with an increasing prevalence of serious infections related to intravenous drug use. These conditions can be diagnostically challenging, and many of the affected patients are vulnerable to stigma and bias. Factors contributing to diagnostic error in these cases include breakdowns in team communication, loss of situational awareness, and inadequate physical examination.
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