Interobserver variability of ankle-brachial index measurements at rest and post exercise in patients with intermittent claudication.

The ankle-brachial index (ABI) post exercise is claimed to play a complementary role in the diagnosis or exclusion of intermittent claudication (IC). The interobserver variability of ABI measurements at rest and post exercise in patients with typical symptoms of IC is the subject of this study with emphasis on ABI post exercise. ABI at rest and post exercise were measured in both legs of 20 patients with typical symptoms of IC. After 15 minutes of rest these measurements were repeated by another observer. Analysis according to Bland-Altman was performed on 40 paired leg measurements at rest and 40 paired leg measurements post exercise. The average ABI at rest for the first observer was 0.84 (standard deviation +/-0.18) and for the second was 0.84 (+/-0.17). Post-exercise averages were 0.73 (+/-0.25) and 0.74 (+/-0.27), respectively. The standard deviation of the ABI difference between observers was 0.08 at rest and 0.15 post exercise. The interobserver variability of the ABI was 10% at rest and 21% post exercise. The interobserver variability post exercise is an important given when rules are defined about how the ABI post exercise translates into a more reliable and objective diagnosis of IC.