What diagnostics are warranted for a 35-year-old HIV (Human Immunodeficiency Virus) positive male patient on Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide) with constant mid bilateral back pain, aside from Complete Blood Count (CBC) and Comprehensive Metabolic Panel (CMP)?

Diagnostic Workup for HIV-Positive Patient with Mid Bilateral Back Pain

For a 35-year-old HIV-positive male patient on Biktarvy for 1 month presenting with constant mid bilateral back pain, magnetic resonance imaging (MRI) of the spine is strongly recommended as the primary diagnostic test beyond CBC and CMP. 1

Initial Evaluation

Laboratory Tests (beyond CBC and CMP):

• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) 1
• Blood cultures (2 sets, aerobic and anaerobic) 1
• Fungal blood cultures (given HIV-positive status) 1
• PPD test or interferon-gamma release assay (IGRA) 1

Imaging:

• Spine MRI (preferred first-line imaging) 1
• If MRI is contraindicated or unavailable: combination spine gallium/Tc99 bone scan, CT scan, or PET scan 1

Rationale for Diagnostic Approach

This patient's presentation raises significant concern for native vertebral osteomyelitis (NVO) or other spine infection due to:

1. New onset back pain in an immunocompromised host (HIV-positive)
2. Recent initiation of antiretroviral therapy (Biktarvy)
3. Constant pain not worsened by movement (typical of infectious rather than mechanical etiology)

The Infectious Diseases Society of America (IDSA) guidelines strongly recommend suspecting NVO in patients with new or worsening back pain and elevated inflammatory markers (ESR/CRP) 1. Additionally, HIV-positive patients are at increased risk for opportunistic infections affecting the spine, particularly after initiating antiretroviral therapy due to immune reconstitution inflammatory syndrome (IRIS).

Special Considerations for HIV Patients

HIV-positive patients are at higher risk for:

• Mycobacterium avium complex vertebral osteomyelitis, especially following initiation of antiretroviral therapy 1
• Fungal infections of the spine
• Multifocal spine infections 1

The recent initiation of Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide) one month ago could potentially be associated with immune reconstitution, making opportunistic infections more likely to manifest clinically 1.

Common Pitfalls to Avoid

1. Delaying diagnosis: The average time to diagnosis of vertebral osteomyelitis can be 2-4 months, with 34% of patients initially misdiagnosed 1
2. Inadequate imaging: Plain radiographs are insufficient for early diagnosis of spine infections
3. Failure to obtain blood cultures: Blood cultures should be obtained before initiating antibiotics
4. Missing atypical pathogens: Consider fungal and mycobacterial infections in HIV patients

Follow-up Recommendations

If initial workup is negative but clinical suspicion remains high:

• Consider spine biopsy guided by imaging 1
• Consultation with infectious disease specialist and spine surgeon 1
• Repeat imaging if symptoms persist despite negative initial studies

By following this diagnostic approach, you can efficiently identify potential infectious causes of back pain in this immunocompromised patient, allowing for timely intervention and improved outcomes.