When is testing for elevated high sensitivity C-Reactive Protein (hs-CRP) considered in patients with risk factors for cardiovascular disease?

Testing for High Sensitivity C-Reactive Protein (hs-CRP) in Cardiovascular Risk Assessment

High-sensitivity C-reactive protein (hs-CRP) testing should primarily be considered in patients at intermediate risk (10-20% risk of coronary heart disease over 10 years) based on traditional risk factor assessment to guide further evaluation and therapy in primary prevention of cardiovascular disease. 1

Patient Selection for hs-CRP Testing

Recommended Candidates:

• Intermediate-risk patients (10-20% 10-year CHD risk) 1

  • These patients benefit most as hs-CRP can reclassify them into higher or lower risk categories
  • An elevated hs-CRP may elevate an intermediate-risk patient to high-risk status (≥20% 10-year CHD risk) 1

• Adults without known cardiovascular disease 1

  • As part of global coronary risk assessment
  • After traditional risk factors have been assessed and an absolute risk score calculated

Not Recommended for:

• Patients already classified as high-risk (≥20% 10-year CHD risk) 1
  • These patients already qualify for intensive medical interventions
• As an alternative to major risk factors for risk assessment 1
• Routine screening of the general population 1

Interpretation of hs-CRP Results

Risk Stratification:

• Low risk: <1.0 mg/L
• Average risk: 1.0-3.0 mg/L
• High risk: >3.0 mg/L 2

Important Considerations:

• For accurate cardiovascular risk assessment, obtain two measurements (optimally 2 weeks apart) 1
• Patients with persistently elevated hs-CRP >10 mg/L should be evaluated for non-cardiovascular causes of inflammation 1
• hs-CRP should not be used as the sole determinant for treatment decisions 1

Clinical Applications

Primary Prevention:

• May help direct further evaluation (e.g., imaging, exercise testing) 1
• May guide therapy decisions (e.g., lipid-lowering, antiplatelet agents) 1
• May motivate patients to improve lifestyle behaviors, though benefits remain uncertain 1

Secondary Prevention:

• May be useful as an independent marker of prognosis for recurrent events in patients with:
  • Stable coronary disease
  • Acute coronary syndromes
  • After percutaneous coronary intervention 1
• However, application of secondary prevention measures should not depend on hs-CRP determination 1

Important Limitations and Caveats

• Do not use hs-CRP for:

  • Serial testing to monitor treatment effects 1
  • Guiding management of acute coronary syndromes 1
  • As a substitute for traditional risk factor assessment 1

• Factors affecting hs-CRP levels:

  • Age, sex, BMI, smoking status
  • Exercise, diet, sleep patterns
  • Underlying inflammatory conditions
  • Medications (statins can lower hs-CRP)

• Wait at least 2-3 weeks after any acute inflammatory stimulus before measuring hs-CRP for cardiovascular risk assessment 1

The evidence supporting hs-CRP testing is strongest for intermediate-risk patients where the additional information can meaningfully impact clinical decision-making. While hs-CRP has demonstrated value in risk prediction, it should always be used as a complement to, not a replacement for, traditional risk factor assessment.