The Baltimore activity scale for intermittent claudication: a validation study

The purpose of this study was to develop and cross-validate the Baltimore Activity Scale for Intermittent Claudication (BASIC) questionnaire in patients with peripheral arterial disease limited by intermittent claudication, and to determine whether the BASIC questionnaire score changed following a supervised program of exercise rehabilitation. A total of 702 consecutive patients with peripheral arterial disease and stable intermittent claudication were characterized on physical activity level using the BASIC questionnaire and an accelerometer. The first 351 patients tested were included in the validation group, whereas the final 351 patients were included in the cross-validation group. Subsequently, 61 of these patients participated in a randomized, controlled trial in which 28 patients completed 6 months of exercise rehabilitation and 24 patients completed usual care control. The sum of 5 questions from the BASIC questionnaire (0-10 point scale) was predictive of daily physical activity using the following regression equation: Daily Physical Activity (kcal/day) = 102.2 + (49.6 x BASIC score); R = 0.76, R(2) = 0.58, standard error of estimate = 52.0 kcal/day, P < .0001. This equation was successfully cross-validated on an independent group of patients, as the predicted daily physical activity (339 - 181 kcal/day, mean - SD) was similar (P = .501) to measured daily physical activity (347 - 266 kcal/day, mean - SD). Furthermore, the BASIC score increased 38% following 6 months of exercise rehabilitation (P < .01), whereas no change was observed in the control group (P > .05). A composite of 5 questions obtained from the self-administered BASIC questionnaire accurately estimates daily physical activity in patients with peripheral arterial disease limited by intermittent claudication, and is sensitive to change in physical activity following a program of exercise rehabilitation.