A systematic review 1 including 78 studies (reporting 82 patient cohorts) was abstracted in DARE. Plethysmography and rheography techniques in deep vein thrombosis diagnosis were examined with contrast venography or ultrasound as the reference standard. Sensitivity and specificity (95% CI) were: 75% (73% to 77%) and 90% (89% to 91%) for impedance plethysmography, 83% (81% to 85%) and 81% (79% to 82%) for strain-gauge plethysmography, 85% (79% to 90%) and 91% (81% to 95%) for air plethysmography, 91% (87% to 94%) and 71% (66% to 75%) for light-reflex rheography, and 86% (83% to 89%) and 93% (91% to 95%) for phleborheography. Meta-regression was limited by poor reporting of studies. There was some evidence that diagnostic performance depended on the proportion of males in the cohort and reporting of study setting. The authors conclude that evaluation of the role of plethysmography and rheography techniques in combination with other tests, or standardised clinical assessment, is required.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in results in different populations).
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