Intermittent Claudication Algorithm

The full reasoning pathway — distinguish stable claudication from limb-threatening ischaemia, confirm PAD with ABPI, drive hard on secondary prevention, prescribe exercise, and safety-net.StartDecisionInvestigateActionReferStop / Admit

PresentationIntermittent claudication

Calf/thigh/buttock pain on walking, relieved by rest. Examine pulses; measure ABPI.

Step 1 · Safety — limb-threatening ischaemiaLimb-threatening ischaemia?

Acute: 6 Ps (pain, pallor, pulseless, perishingly cold, paraesthesia, paralysis) → 999. Critical: rest pain, ulceration or gangrene.

YES

Stop · Escalate999 / urgent vascular

Acute limb ischaemia → 999. Critical limb ischaemia → urgent vascular referral.

InvestigateABPI + risk factors

ABPI <0.9 confirms PAD. Exclude neurogenic claudication (spinal stenosis). HbA1c, lipids.

Step 7 · manage

Step 7 · Action · Secondary preventionTreat the arteries, not just the legs

Smoking cessation, supervised exercise programme, statin + antiplatelet, optimise BP and diabetes. PAD is a coronary-risk equivalent.

Step 6 · ReferVascular surgery

999 acute limb ischaemia. Vascular critical ischaemia or lifestyle-limiting claudication despite exercise + risk-factor therapy (angioplasty/bypass).

Step 8 · exercise & risk-factor modification

Step 8 · Lifestyle — more effective than drugs aloneWalk through the pain, treat the whole tree

Supervised exercise programme is first-line (walk to near-maximal claudication, rest, repeat; ≥2 h/week for 3 months) and improves walking distance more than drugs. Stop smoking (the single biggest modifiable risk) · weight loss, Mediterranean diet · optimise BP, diabetes and lipids · daily foot care/inspection (especially in diabetes) and well-fitting footwear.

Step 9 · follow-up & safety-net

Step 9 · Follow-up & safety-netMonitor & urgent return advice

Review walking distance, risk factors and medication adherence; reassess statin/antiplatelet and BP/diabetes targets. 999 / same-day vascular for the 6 Ps of acute limb ischaemia (pain, pallor, pulselessness, paraesthesia, paralysis, perishingly cold), or rest pain / ulceration / gangrene (critical limb ischaemia). Counsel that new foot ulcers or night/rest pain are red flags needing urgent review.

⚠️ Claudication is a cardiovascular red flag: these patients are at high risk of MI and stroke — the legs are the presenting complaint, but secondary prevention saves lives.

Safety

Red flags — critical limb ischaemia & cardiovascular emergencies

Done

Claudication itself is not an emergency, but critical limb ischaemia is. Screen every patient with PAD at every visit.

Rest pain (especially nocturnal) Severe constant ischaemic pain in foot/toes at rest → 999 or same-day vascular (critical limb ischaemia)

6 Ps — acute ischaemia Pain, Pallor, Pulselessness, Paraesthesia, Paralysis, Perishing cold → 999 immediately (6-hour window)

Tissue loss Ischaemic ulcers (punched-out, painful, distal), dry/wet gangrene of toes → same-day emergency vascular referral

Acute cardiovascular event Chest pain + claudication = very high CV risk. New chest pain/stroke symptoms → 999

Acute aortic symptoms Sudden severe back/abdominal pain + absent femoral pulses → 999 (aortic occlusion/dissection/AAA rupture)

Rapidly worsening claudication Claudication distance halving over weeks → same-day vascular (acute-on-chronic ischaemia)

Critical limb ischaemia has a 1-year major amputation rate of 25–40% without revascularisation. The 6-hour window for acute limb ischaemia is analogous to STEMI — irreversible muscle death occurs after 6h of ischaemia. PAD patients have a 3–5x increased risk of MI and stroke — cardiovascular events kill more PAD patients than limb complications.

Diagnose

Confirm claudication — Edinburgh Claudication Questionnaire

Done

Claudication = reproducible calf/leg pain on walking, relieved by rest within 10 minutes (standing still, not sitting). Use Edinburgh Claudication Questionnaire (ECQ) to classify.

Classic claudication

Calf pain on walking, always goes away on rest within 10 min, not present at rest. ECQ positive = 91% sensitivity, 99% specificity for PAD

Atypical claudication

Thigh/buttock claudication (aorto-iliac disease), foot claudication (tibial disease). May have associated erectile dysfunction (Leriche syndrome)

Claudication distance

Record: (1) initial claudication distance (pain starts) and (2) absolute claudication distance (stops walking). Track over time

Not claudication

Pain on standing still (spinal stenosis = neurogenic claudication — worse on extension, better flexed forward) | DVT | Arthritis | Compartment syndrome

Fontaine staging

I: Asymptomatic PAD | IIa: Claudication >200m | IIb: Claudication <200m | III: Rest pain | IV: Tissue loss

Neurogenic claudication (spinal stenosis) is the main differential — it worsens going downhill, improves going uphill, and is relieved by sitting not standing. Leriche syndrome (aorto-iliac occlusion) causes buttock claudication and erectile dysfunction in younger men — often missed. Fontaine stage predicts prognosis and guides referral urgency.

Diagnose

Cardiovascular risk stratification — PAD is a CVD equivalent

Done

Diagnosis of PAD immediately places the patient in the highest cardiovascular risk category. Address all modifiable risk factors.

Risk factors to assess

Smoking (most powerful), diabetes, hypertension, dyslipidaemia, CKD, family history of vascular disease. Calculate QRISK3

ABPI interpretation

0.9–1.3 = Normal | 0.7–0.9 = Mild PAD | 0.5–0.7 = Moderate PAD | <0.5 = Severe PAD/critical ischaemia | >1.3 = Calcified vessels (diabetes)

Polyvascular disease

Ask about: chest pain, TIA/stroke symptoms, carotid bruit. PAD + another vascular territory = very high CV event risk

Diabetes + PAD

ABI may be falsely normal/high (calcification). Use toe-brachial index (TBI) — more accurate. Neuropathy masks ischaemic pain

PAD is a CAD equivalent for statin and antiplatelet therapy — 10-year CV event rate >20% by definition. Smoking cessation is the most effective single intervention, improving claudication distance by 30–50% and reducing amputation risk by 50%. Calcified vessels in diabetes give falsely reassuring ABIs — the most common diagnostic error in diabetic foot disease.

Diagnose

Targeted examination

Done

ABPI Essential

Measure both legs. Doppler probe + sphygmomanometer. Ratio = highest ankle pressure ÷ brachial pressure. Asymmetry alone is significant

Peripheral pulses

Palpate and grade: femoral, popliteal, dorsalis pedis, posterior tibial. Document absent/reduced pulses bilaterally

Skin changes

Dependent rubor, pallor on elevation (Buerger's test), hair loss, shiny thin skin, cool temperature, trophic nail changes, ischaemic ulcers

Buerger's angle

Elevate leg — pallor at <15° = critical ischaemia. Dependent rubor on lowering = reactive hyperaemia

Auscultation

Femoral bruits (stenosis). Carotid bruits. Abdominal aortic aneurysm (AAA) — consider if >65M or >70F with vascular risk factors

Neurological

Exclude diabetic neuropathy (monofilament testing, vibration sense) — important co-morbidity affecting management

ABPI is the single most important test in primary care PAD assessment — it has 95% sensitivity and 99% specificity for significant PAD. Buerger's test positive at <15° identifies critical ischaemia clinically before ABPI. All men >65 in the UK are offered NHS AAA screening — check if this has been done and document result.

Diagnose

Investigations

Done

ABPI Essential

If <0.9 = PAD confirmed. Refer for duplex ultrasound. If >1.3 (calcification) → toe-brachial index (TBI) instead

Bloods Essential

HbA1c, lipid profile (LDL target <1.8 mmol/L in PAD), FBC, U&E, eGFR (contrast contraindication for imaging), CRP

ECG

AF (anticoagulation changes management), ischaemic changes — PAD + AF = high stroke risk

Duplex USS

Ordered by vascular team. Identifies location and severity of stenosis/occlusion. Guides intervention planning

Not routinely in PC

CT angiography, MRA — ordered by vascular team pre-intervention. Do not order in primary care

AAA screen

Abdominal USS if >65M not previously screened. AAA prevalence 3x higher in PAD patients vs general population

LDL target in PAD is <1.8 mmol/L (ESC 2019) — far lower than primary prevention targets. Most UK PAD patients are under-statin-dosed. eGFR <30 is a relative contraindication for iodinated contrast used in CT angiography — document before referral. AF + PAD + anticoagulation dramatically reduces stroke and limb event risk.

Refer

Referral criteria — vascular surgery

Done

999 Emergency

Acute limb ischaemia (6 Ps) | Rest pain with complete pulse absence | Suspected aortic emergency

Same-day

Critical limb ischaemia (rest pain, tissue loss, ABI <0.5) | Rapidly deteriorating claudication | Wet gangrene

Urgent vascular

Claudication <200m limiting daily activities | ABI <0.7 with significant symptoms | Failed 3 months of supervised exercise | Suspected aorto-iliac disease (Leriche)

Routine vascular

Confirmed PAD (ABI <0.9) for duplex USS and supervised exercise programme. Even if not for intervention — multidisciplinary risk reduction

Primary care manages

Mild claudication (>200m), ABI 0.7–0.9, stable symptoms — smoking cessation, exercise, antiplatelet, statin, BP control

NICE NG19 (2020): all PAD patients should be offered supervised exercise programme (12 sessions over 3 months) — improves walking distance by 50–120m (equivalent to angioplasty for mild-moderate claudication). Referral to vascular MDT also enables cardiovascular risk optimisation. Intervention (angioplasty/bypass) reserved for significant disability or critical ischaemia.

Treat

Medical management — cardiovascular risk reduction is the priority

Done

Antiplatelet therapy

Clopidogrel 75 mg OD First-line

Superior to aspirin for PAD (CAPRIE trial — 23.8% relative risk reduction). Start all symptomatic PAD patients

If clopidogrel intolerant

Aspirin 75 mg OD

Second-line antiplatelet. Reduce GI risk with PPI if history of dyspepsia

High-intensity statin

Atorvastatin 80 mg OD Essential

Target LDL <1.8 mmol/L. Reduces major CV events by 25%. Do not wait for lipid result to start

BPTarget <140/90 mmHg (or <130/80 if diabetes). ACE inhibitor/ARB first-line. Caution: beta-blockers not contraindicated in PAD (NICE NG19) but can worsen claudication subjectively

DiabetesHbA1c <53 mmol/mol (7%). Tight glucose control slows PAD progression. SGLT2 inhibitors have cardiovascular and renal benefits in PAD + diabetes

Cilostazol100 mg BD — phosphodiesterase inhibitor. Improves claudication distance by 40–60m. Use if supervised exercise fails. Contraindicated: heart failure, avoid with anticoagulants

AnticoagulationRivaroxaban 2.5 mg BD + aspirin 100 mg OD (COMPASS trial) if high-risk PAD (ABI <0.8, prior revascularisation) — discuss with vascular team first

CAPRIE trial: clopidogrel reduces combined MI/stroke/vascular death by 23.8% vs aspirin in PAD patients. High-intensity statins (atorvastatin 80mg) reduce 5-year major adverse limb events by 18% in PAD (Bhatt et al). COMPASS trial: rivaroxaban 2.5mg BD + aspirin reduced MACE and MALE (major adverse limb events) by 28% vs aspirin alone — NICE recommends consideration in high-risk stable PAD.

Lifestyle

Exercise & risk factor modification — more effective than medication alone

Done

Supervised exercise programme 12 sessions over 3 months, 30–60 min each. Walk to near-maximum claudication pain then rest. Improves walking distance by 50–200% — equivalent to angioplasty. Refer via vascular team or community exercise on prescription

Smoking cessation Single most important intervention. Reduces claudication progression by 30–50%, halves amputation risk, reduces MI rate. Refer to NHS Stop Smoking Service. Varenicline + NRT most effective combination

Mediterranean diet Reduces cardiovascular events by 30% (PREDIMED). High fruit, vegetables, olive oil, fish, legumes. Avoid saturated fat and processed foods

Foot care Daily inspection for blisters, cuts, colour change. Well-fitting footwear. Podiatry referral for diabetics. Any wound in PAD patient = medical urgency

Weight reduction Target BMI <25 kg/m². Each 10 kg weight loss reduces CV event risk by 9 mmHg BP reduction and 0.5 mmol/L LDL fall

Alcohol reduction <14 units/week. Excess alcohol raises triglycerides and BP. Safe levels may have mild vasodilatory benefit but not a reason to drink

A Cochrane review (2017) shows supervised exercise improves maximum walking distance by 120m on average vs angioplasty improving by 80m — exercise is more effective than intervention for stable claudication. Smoking cessation is the only intervention proven to slow PAD progression AND reduce cardiovascular mortality. NICE NG19 mandates supervised exercise as first-line for claudication before any intervention is considered.

Safety

Follow-up & monitoring

Done

3 months

Review: claudication distance improving? Adherence to exercise/smoking cessation? LDL achieved <1.8? BP at target? Medications tolerated?

6 months

Repeat ABPI if symptoms changing. Check HbA1c, lipids, renal function (if on ACEi/ARB). Reinforce exercise and lifestyle

Annual

Full cardiovascular risk review. ABPI annually in known PAD. Foot inspection. ECG (AF surveillance). Medication review

999 safety-net

Sudden severe leg pain + pallor + cold + loss of pulse → 999 immediately (acute ischaemia). Chest pain, stroke symptoms

Same-day

Rest pain developing | Any foot wound/ulcer | Rapidly worsening claudication distance | New neurological symptoms in leg

Foot wounds

Any break in skin in a PAD patient = same-day review. Risk of non-healing and limb loss is very high. Do not adopt watch-and-wait approach

Annual MI rate in stable PAD patients is 5–7% — higher than most stable angina patients. Regular cardiovascular review (BP, lipids, HbA1c) reduces event rate. ABPI tracking identifies deterioration before critical ischaemia — a fall in ABI of 0.15 over 12 months is clinically significant. Ischaemic foot wounds heal poorly and progress to amputation in weeks without urgent vascular input.