Key result
Standardized physical function questions were highly sensitive but poorly specific for identifying patients who achieve moderate physical activity.
Why the study?
Functional capacity assessment is a core component of perioperative cardiovascular evaluation guidelines, but the ability of standardized physical function questions to predict accelerometer-measured moderate physical activity required investigation.
Do standardized physical function questions accurately predict moderate-vigorous physical activity measured by accelerometry in adults with cardiac risk factors?
Cross-Sectional (n=522)
Do standardized physical function questions accurately predict moderate-vigorous physical activity measured by accelerometry in adults with cardiac risk factors?
Standardized physical function questions used in perioperative evaluation are highly sensitive but poorly specific for identifying patients who actually achieve moderate physical activity, suggesting additional evaluation strategies may be needed.
Answers are grounded in this paper and cite their sources.
Low specificity limits reliance on questions alone for activity assessment in cardiac patients; leaves open need for validated objective measures in future studies.
BACKGROUND: Functional capacity assessment is a core component of current perioperative cardiovascular evaluation and management guidelines for noncardiac surgery. The authors investigated the ability of standardized physical function questions to predict whether participants engaged in moderate physical activity as measured by hip accelerometers. METHODS: Participant responses to physical functioning questions and whether they engaged in moderate physical activity were extracted from the National Health and Nutrition Examination Survey (2003 to 2004 and 2005 to 2006). Physical activity intensity was measured using hip accelerometers. Adult participants with at least one Revised Cardiac Risk Index condition were included in the analysis. Standardized physical function questions were evaluated using a classification and regression tree analysis. Training and test datasets were randomly generated to create and test the analysis. RESULTS: Five hundred and twenty-two participants were asked the physical functioning questions and 378 of 522 (72.4%) had a bout of moderate-vigorous activity. Classification and regression tree analysis identified a "no difficulty" response to walking up 10 stairs and the ability to walk two to three blocks as the most sensitive questions to predict the presence of a 2-min bout of moderate activity. Participants with positive responses to both questions had a positive likelihood ratio of 3.7 and a posttest probability greater than 90% of a 2-min bout of moderate-vigorous activity. The sensitivity and specificity of positive responses to physical functioning questions in the pruned tree were 0.97 (95% CI, 0.94 to 0.98) and 0.16 (95% CI, 0.10 to 0.23) for training data, and 0.88 (95% CI, 0.75 to 0.96) and 0.10 (95% CI, 0.00 to 0.45) for the test data. Participants with at least one 2-min bout of moderate activity had a greater percentage of overall daily active time (35.4 ± 0.5 vs. 26.7 ± 1.2; P = 0.001) than those without. CONCLUSIONS: Standardized physical function questions are highly sensitive but poorly specific to identify patients who achieve moderate physical activity. Additional strategies to evaluate functional capacity should be considered.
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Rubin et al. (2019) conducted a cross-sectional in Adults with at least one Revised Cardiac Risk Index condition (n=522). Standardized physical function questions vs. Hip accelerometry was evaluated on Presence of a 2-min bout of moderate activity (Sensitivity 0.88, 95% CI 0.75-0.96). Standardized physical function questions were highly sensitive but poorly specific for identifying patients who achieve moderate physical activity.
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