Reporting success rate at 12 months after percutaneous treatment for peripheral arterial disease: the impact of outcome criteria.

Objective: The objectives of our study were to assess the influence of varying outcome criteria on the success rate at 12 months after percutaneous intervention for peripheral arterial disease and to suggest a reporting method that can be used in studies that report results of interventions as measured by parameters of daily clinical practice.

Materials And Methods: The outcomes of 1,411 consecutive procedures in 1,583 limbs recorded in a multicenter registry involving six hospitals were analyzed. Six sets of outcome criteria were evaluated: one based on symptomatic change, three based on ankle-brachial index (ABI) measurements, and two based on combining the symptomatic and ABI outcome measures. Agreement among the outcome measures was compared using the kappa statistic.

Results: The ABI outcome measures alone showed good agreement (kappa = 0.74-0.94). The symptomatic outcome measures yielded a substantially higher 12-month success rate than the ABI outcome measures (difference, 18-24%) and the agreement was only fair (kappa = 0.52-0.60). The agreement between symptomatic outcome and ABI outcome measures was poor in patients with a pretreatment ABI measurement at rest of more than 0.90 (kappa = 0.20). Combining symptomatic outcome and the ABI outcome measures with the logical operator "OR" showed good agreement with the symptomatic outcome measures alone (kappa = 0.97) and using "AND" showed good agreement with the ABI outcome measures alone (kappa = 0.87).

Conclusion: In patients with a pretreatment ABI measurement at rest of more than 0.90, classifying procedures using a criterion based on improvement in ABI measurements with more than 0.10 is inaccurate and underestimates the actual success rate at 12 months after percutaneous intervention. Furthermore, combining subjective improvement in symptoms and improvement in ABI measurements does not yield more information than reporting these outcome measures separately. Therefore, we suggest that improvement in symptoms and improvement in ABI measurements should be reported separately to indicate the 12-month success rate of percutaneous interventions for peripheral arterial disease.