Optimal diagnostic thresholds for diagnosis of orthostatic hypotension with a 'sit-to-stand test'

Abstract

Objective: This study aimed to identify optimal blood pressure cut-offs to diagnose orthostatic hypotension during a sit-to-stand manoeuvre.

Methods: This was a cross-sectional study of patients and healthy controls from the Vanderbilt Autonomic Dysfunction Center. Blood pressure was measured while supine, seated and standing. Blood pressure changes were calculated from supine-to-standing and seated-to-standing. Orthostatic hypotension was diagnosed on the basis of a supine-to-standing SBP drop at least 20 mmHg or a DBP drop at least 10 mmHg. Receiver operator characteristic (ROC) curves identified optimal sit-to-stand cut-offs.

Results: Amongst the 831 individuals, more had systolic orthostatic hypotension [n = 354 (43%)] than diastolic orthostatic hypotension [n = 305 (37%)] during lying-to-standing. The ROC curves had good characteristics [SBP area under curve = 0.916 (95% confidence interval: 0.896-0.936), P < 0.001; DBP area under curve = 0.930 (95% confidence interval: 0.909-0.950), P < 0.001]. A sit-to stand SBP drop at least 15 mmHg had optimal test characteristics (sensitivity = 80.2%; specificity = 88.9%; positive predictive value = 84.2%; negative predictive value = 85.8%), as did a DBP drop at least 7 mmHg (sensitivity = 87.2%; specificity = 87.2%; positive predictive value = 80.1%; negative predictive value = 92.0%).

Conclusions: A sit-to-stand manoeuvre with lower diagnostic cut-offs for orthostatic hypotension provides a simple screening test for orthostatic hypotension in situations wherein a supine-to-standing manoeuvre cannot be easily performed. Our analysis suggests that a SBP drop at least 15 mmHg or a DBP drop at least 7 mmHg best optimizes sensitivity and specificity of this sit-to-stand test.

Figure 1

Flow diagram for participant selection and testing.

Figure 2

Receiver operator characteristic curves for the detection of orthostatic hypotension during sit-to-stand testing. Legend. Receiver operator characteristic curves for the detection of orthostatic hypotension during sit-to-stand testing using systolic blood pressure criteria (A) and diastolic blood pressure criteria (B). The red line is the plot of the true positive rate (sensitivity) against the false positive rate (1-specificity). The diagonal line represents the line of no-discrimination. The vertical black line represents where the Youden Index (J) is maximized; it is highest for a SBP drop cut-point of 15 mmHg (J= 0.691), and a DBP drop cut-point of 7 mmHg (J=0.744).