Pulse volume recording does not enhance segmental pressure readings for peripheral arterial disease stratification

Noninvasive vascular laboratory determinations for peripheral arterial disease (PAD) often combine pulse volume recordings (PVRs), segmental pressure readings (SPs), and Doppler waveform traces (DWs) into a single diagnostic report. Our objective was to assess the corresponding diagnostic values for each test when subjected to interpretation by 4 vascular specialists.

A total of 2226 non-invasive diagnostic reports were reviewed through our institutional database between January 2009 and December 2011. Data from noninvasive records with corresponding angiograms performed within 3 months led to a cohort of 76 patients (89 limbs) for analysis. Four vascular specialists, blinded to the angiographic results, stratified the noninvasive studies as representative of normal, <50% "subcritical," or ≥50% "critical" stenosis at the upper thigh, lower thigh, popliteal, and calf segments using 4 randomized noninvasive modalities: (1) PVR alone; (2) SP alone; (3) SP+DW; and (4) SP+DW+PVR. The angiographic records were independently graded by another 3 evaluators and used as a standard to determine the noninvasive diagnostic values and interobserver agreements for each modality. Statistical tests used include the Fleiss-modified kappa analysis, Kruskal-Wallis analysis of variance with Dunn's multiple comparison test, the Kolmogorov-Smirnov test, and the unpaired t-test with Welch's correction.

Interobserver variance for all modalities was high, except for SP. When surveying for any stenosis (<50% and ≥50%), sensitivity (range 25-75%) was lower than specificity (range 50-84%) for all modalities. When surveying for critical stenosis only (≥50%), sensitivity (range 27-54%) was also lower than specificity (range 68-92%). Accuracy for detecting any stenosis with SP+DW was significantly higher than with PVR alone (66 ± 7% vs. 56 ± 12%, P = 0.017). There was a significant reduction in accuracy when including incompressible readings within the SP-only analysis compared with exclusion of incompressible vessels (P = 0.0006). However, the effect of vessel incompressibility on accuracy was removed with the addition of DW (P = 0.17) to the protocol.

SP has the greatest interobserver agreement in evaluation of PAD and can be used preferentially for PAD stratification. Given the lower accuracy of PVR for detecting either subcritical or critical disease, PVR tests can be omitted from the noninvasive vascular examination without a significant reduction in overall diagnostic value and can be reserved for patients with incompressible vessels.