Background. Intermittent claudication has long been considered the most classic manifestation of PAD. The evaluation of claudication severity requires a comprehensive approach, using outpatient walking ability, physical activity, and quality of life. At present, claudication distance may be assessed using different approaches, including treadmill testing and the six minute walk test (6MWT). However, these two approaches have not been applied yet to determine claudication distance in Filipino patients. The study aimed to determine if the claudication distance measured using the 6MWT is comparable with the claudication distance using the treadmill stress test in Filipino patients diagnosed to have peripheral arterial disease at the Philippine Heart Center. These distances were also correlated with Fontaine stage determined clinically.
Methods. This is a cross-sectional study wherein patients diagnosed with PAD at the Peripheral Vascular Clinic underwent treadmill exercise test (TET) and 6 MWT. The distance at which the patient first notices the onset of claudication pain is recorded (initial claudication distance, or ICD), and when the patient reaches a maximal level of claudication pain (absolute claudication distance, or ACD) were obtained and compared. Hemodynamic parameters including blood pressure and heart rate were also determined and compared between the two tests.
Results. A total of 16 patients were included in the study. Compared to the TET, patients had longer distances walked before experiencing claudication with the 6 MWT All patients performed well during the 6MWT in terms of their perceived walking distance at home and during their daily activities. The mean ICD for the 6MWT and TET were 101.25 ± 111.15 meters and 61.37 ± 58.06 meters (p=0.202) and the mean ACD were 357.06 ± 51.31 and 152.81 ± 107.85 meters (p=0.00). The ICDs in both groups were comparable. However, there was a statistically significant difference between the groups in terms of ACD. Distances measured and the Fontaine stage to which the patient was assigned were also correlated. Larger increases in systolic blood pressure and heart rate were noted with the treadmill group, together with a trend toward a larger increase in diastolic blood pressure. Using the metabolic equivalents (METS) obtained with the treadmill test, patients in the Fontaine Stage I group had the best functional capacity, followed by those in the Fontaine Stage IIA group, then those in the Fontaine Stage IIB group.
Conclusion. The 6 MWT is a safe, inexpensive, reliable and reproducible alternative to TET in determining the claudication distance and functional capacity of patients with peripheral arterial disease. Also, 6 MWT is more preferred by patients. This would be ideal for patients who cannot afford to undergo a treadmill exercise test and may easily be done along the corridor of a hospital or clinic if needed.