Reliability of treadmill testing in peripheral arterial disease: a comparison of a constant load with a graded load treadmill protocol

• Published in: Vascular medicine (London) 1999-11, Vol.4 (4), p.239-246
• Main Authors: Labs, Karl-Heinz, Nehler, Mark R, Roessner, Martin, Jaeger, Kurt A, Hiatt, William R
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Double-Blind Method; Epoprostenol - therapeutic use; Exercise Test - methods; Exercise Test - standards; Female; Humans; Infant, Newborn; Intermittent Claudication - drug therapy; Intermittent Claudication - physiopathology; Longitudinal Studies; Male; Medical sciences; Middle Aged; Reproducibility of Results
• ISSN: 1358-836X; 1358-863X; 1477-0377
• DOI: 10.1177/1358836X9900400406

This study aims to evaluate the reliability of repeated graded workload treadmill testing (G-test; 2 mph; 0% grade, increasing 2% every 2 min) and to compare the reliability of a constant workload treadmill protocol (C-test; 2 mph; 12% grade) versus the graded workload treadmill protocol in patients with intermittent claudication, studied longitudinally. A clinical trial investigating an orally stable prostacycline derivative that included 330 patients with intermittent claudication was performed. The trial employed three active treatment groups and one placebo group. Because there were no significant inter-group differences at baseline or after treatment, data from all groups were pooled for the evaluation of treadmill test reliability. Treadmill data were obtained from a 2-week run-in phase where three G-tests were performed, as well as from the beginning and the end of a 3-month double-blind phase where a G-test and a C-test were performed in random order. Treadmill test reliability was described through test process-related and between-subject variances and also using variance-derived parameters such as the reliability coefficient (RC) and the relative precision (RP). A higher value for the RC and a lower value for the RP indicate that the test variability is predominantly due to between-subject variance and not to test process-related variance. Estimates of variance were described for both the maximal or absolute claudication distance (ACD) and the initial claudication distance (ICD) with each treadmill test. Reliability estimates are reported for the total study sample and for patients with baseline claudication distances