Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis.


Abstract

Objective To review the diagnostic accuracy of D-dimer testing in older patients (>50 years) with suspected venous thromboembolism, using conventional or age adjusted D-dimer cut-off values.

Design Systematic review and bivariate random effects meta-analysis.

Data sources We searched Medline and Embase for studies published before 21 June 2012 and we contacted the authors of primary studies.

Study selection Primary studies that enrolled older patients with suspected venous thromboembolism in whom D-dimer testing, using both conventional (500 µg/L) and age adjusted (age×10 µg/L) cut-off values, and reference testing were performed. For patients with a non-high clinical probability, 2×2 tables were reconstructed and stratified by age category and applied D-dimer cut-off level.

Results 13 cohorts including 12 497 patients with a non-high clinical probability were included in the meta-analysis. The specificity of the conventional cut-off value decreased with increasing age, from 57.6% (95% confidence interval 51.4% to 63.6%) in patients aged 51-60 years to 39.4% (33.5% to 45.6%) in those aged 61-70, 24.5% (20.0% to 29.7% in those aged 71-80, and 14.7% (11.3% to 18.6%) in those aged >80. Age adjusted cut-off values revealed higher specificities over all age categories: 62.3% (56.2% to 68.0%), 49.5% (43.2% to 55.8%), 44.2% (38.0% to 50.5%), and 35.2% (29.4% to 41.5%), respectively. Sensitivities of the age adjusted cut-off remained above 97% in all age categories.

Conclusions The application of age adjusted cut-off values for D-dimer tests substantially increases specificity without modifying sensitivity, thereby improving the clinical utility of D-dimer testing in patients aged 50 or more with a non-high clinical probability.

 

What is already known on this topic

  • A negative D-dimer test can rule out venous thromboembolism in patients with a non-high clinical probability
  • Since D-dimer levels increase with age, the proportion of false positive D-dimer test results for venous thromboembolism using conventional cut-off values (500 µg/L) increases in older patients and the specificity decreases
  • Age adjusted D-dimer cut-off values (age×10 µg/L) have therefore been introduced
  • This systematic review and meta-analysis established a poor specificity (around 15%) of D-dimer testing with the conventional cut-off value in the eldest patients (>80 years)
  • The application of the age adjusted cut-off value increased the specificity of the D-dimer test to 35% in the eldest patients, while hardly affecting the sensitivity
  • Use of age adjusted D-dimer cut-off values would result in imaging examinations being correctly avoided in 30-54% of older patients with a non-high clinical probability of venous thromboembolism.
  • Source: BMJ

What this study adds

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