Article Impact Level: HIGH Data Quality: STRONG Summary of BMJ Open, 15(6), e094389. https://doi.org/10.1136/bmjopen-2024-094389 Dr. Sinead T. J. McDonagh et al.
Points
- An analysis of 33,710 participants found mean ankle systolic blood pressure is consistently 12.0 mm Hg higher than systolic blood pressure measured in the arm.
- A newly developed multivariable model demonstrated excellent performance in accurately predicting a patient’s arm blood pressure using only the measurement taken from their ankle.
- The predictive model’s accuracy was superior to existing arithmetic formulas, and validation metrics like AUROC curves, sensitivities, and specificities consistently exceeded a value of 0.80.
- Direct ankle SBP measurements were not significantly associated with an increased risk for all-cause mortality or specific cardiovascular mortality in the patient cohort.
- However, a lower reading of ankle systolic blood pressure was significantly associated with a heightened risk of experiencing fatal or non-fatal cardiovascular events during follow-up.
Summary
An individual participant data (IPD) meta-analysis was conducted to develop and validate a model for predicting arm systolic blood pressure (SBP) from ankle SBP measurements and to determine prognostic associations with cardiovascular outcomes. The analysis included 33,710 participants from 14 prospective studies, with a mean age of 58 (45% female) and a mean baseline arm blood pressure of 138/80 mm Hg (SD: 20/12). On average, mean ankle SBP was 12.0 mm Hg higher than arm SBP (95% CI 8.8 to 15.2). This foundational finding highlights the systemic difference between measurement sites, necessitating a more sophisticated approach than simple arithmetic correction.
A multivariable hierarchical linear regression model was developed to estimate arm SBP from ankle SBP. The model demonstrated excellent performance upon validation, with area under the receiver operating characteristic (AUROC) curves, sensitivities, and specificities all exceeding 0.82, 0.80, and 0.82, respectively, across all hypertensive thresholds from 130 to 160 mm Hg. The performance of this predictive model was superior to that of existing fixed arithmetic formulae. The model has been operationalized for clinical application as a publicly available online calculator to facilitate accurate SBP estimation in patients for whom arm measurements are not feasible.
Prognostic associations were examined using Cox proportional hazards models. Ankle SBP was not significantly associated with all-cause mortality (HR 1.000; 95% CI 0.997 to 1.002) or cardiovascular mortality (HR 1.001; 95% CI 0.996 to 1.005). However, a statistically significant association was observed between the lower-reading ankle SBP and the risk of fatal or non-fatal cardiovascular events (HR 1.005; 95% CI 1.002 to 1.007; p<0.001). These findings suggest that while a validated model can accurately estimate central SBP, the direct prognostic value of ankle SBP itself is primarily linked to non-fatal cardiovascular events.
Link to the article: https://bmjopen.bmj.com/content/15/6/e094389
References McDonagh, S. T. J., Warren, F. C., Sheppard, J. P., Boddy, K., Farmer, L., Shore, H., Williams, P., Lewis, P. S., Fordham, A. J., Martin, U., Aboyans, V., & Clark, C. E. (2025). Arm Based on LEg blood pressures (Able-bp): Can systolic ankle blood pressure measurements predict systolic arm blood pressure? An individual participant data meta-analysis from the INTERPRESS-IPD Collaboration. BMJ Open, 15(6), e094389. https://doi.org/10.1136/bmjopen-2024-094389
