Should I proceed with the Ankle-Brachial Index (ABI) test to assess for Peripheral Artery Disease (PAD) in an older adult patient with a history of smoking, possible psoriatic arthritis, foot pain, lumbar stenosis, and radicular leg pain?

Yes, Proceed with ABI Testing Despite Confounding Lumbar Stenosis

You should absolutely proceed with the Ankle-Brachial Index (ABI) test in this patient, as the presence of lumbar stenosis and radicular pain does not exclude—and may actually coexist with—peripheral artery disease (PAD), particularly given the smoking history. 1, 2

Why ABI Testing is Critical in This Clinical Scenario

Strong Class I Indication Based on Risk Factors

• The 2017 ACC/AHA guidelines provide a Class I recommendation for ABI testing in patients ≥50 years old with smoking history, which your patient meets 1, 2
• Smoking is the single most important modifiable risk factor for PAD, and this patient's smoking history alone mandates ABI assessment 2
• The combination of age, smoking history, and foot pain creates a high-risk profile where PAD prevalence can reach 18-40% 3

Lumbar Stenosis Does NOT Rule Out PAD

• Concomitant PAD occurs in 4-7% of patients with lumbar spinal stenosis (LSS), making this a clinically significant overlap 4, 5, 6
• Both conditions cause intermittent claudication, and the presence of one does not exclude the other 4, 5
• Research demonstrates that patients with both LSS and PAD have worse outcomes and less improvement in quality of life compared to LSS alone 6

Normal Pulses Cannot Exclude PAD

• Palpable pedal pulses do not reliably rule out PAD—physical examination has low sensitivity for detecting mild to moderate PAD in asymptomatic or minimally symptomatic patients 1, 2
• The ABI test is 95% sensitive and specific for angiographic PAD when <0.90, far superior to pulse examination 2

Clinical Algorithm for This Patient

Step 1: Perform Bilateral Resting ABI

• Measure ABI in both legs to establish baseline 1
• This is a simple, noninvasive test that takes minimal time 1

Step 2: Interpret Results

• If ABI ≤0.90: PAD is confirmed 1, 2, 7
• If ABI 0.91-0.99: Borderline; consider exercise ABI testing if symptoms persist 1, 7
• If ABI >1.40: Noncompressible vessels (common in diabetes/elderly); must obtain toe-brachial index (TBI) 2, 8, 7
• If ABI 1.00-1.40 but symptoms persist: Consider exercise treadmill ABI testing to evaluate for exercise-induced ischemia 8

Step 3: Risk Stratification Based on Findings

• If PAD is confirmed, this patient faces 25-35% risk of MI or stroke over 5 years, plus 25% mortality risk 2
• Undiagnosed PAD poses particular perioperative risk, especially with immobilization and continued smoking 2

Critical Pitfalls to Avoid

Don't Assume Radicular Pain Explains Everything

• Smoking increases the risk of both chronic radicular neuropathic pain AND PAD independently 9
• Higher nicotine dependence correlates with increased likelihood of chronic radicular neuropathic leg pain (71.3% increase per unit on Fagerström test) 9
• The radicular pain may be real, but vascular disease can coexist and requires separate evaluation 4, 5

Don't Delay Testing Due to "Confounding" Symptoms

• Studies specifically examining LSS patients found that diabetes, advanced age, and history of cerebrovascular disease or ischemic heart disease are independent risk factors for concomitant PAD 5, 6
• If your patient has possible psoriatic arthritis (inflammatory condition), this adds another layer of cardiovascular risk 1
• 3.2% of LSS patients have undetected PAD that would be missed without ABI screening 6

Don't Rely on Clinical Judgment Alone

• The PREVALENT clinical prediction model shows that smoking alone adds 7 points to PAD risk (versus 2 points for "ever smoked"), making current/recent smokers particularly high-risk 3
• When stroke or ischemic heart disease history is present (as may be relevant with psoriatic arthritis cardiovascular risk), these are independent predictors of PAD in LSS patients 4

Bottom Line

The ABI test should be performed now, not deferred. The test is quick, noninvasive, and guideline-mandated for this risk profile. 1, 2 The presence of lumbar stenosis and radicular symptoms represents a clinical scenario where PAD is actually MORE likely to be missed, not less likely to exist. 4, 5, 6 Missing PAD in this patient could result in preventable cardiovascular morbidity and mortality. 2