Sitting and standing blood pressure measurements are not accurate for the diagnosis of orthostatic hypotension – Source: QJM, Mar 9, 2009

Introduction: Orthostatic hypotension (OH) is associated with troublesome symptoms and increased mortality. It is treatable and deserving of accurate diagnosis. This can be time consuming. The current reference standard for its diagnosis is head-up tilt (HUT) testing with continuous beat-to-beat plethysmography.

Our objective was to assess the accuracy of sit-stand testing with semi-automatic sphygmomanometry for the diagnosis of orthostatic hypotension.

Design: Retrospective test of diagnostic accuracy.

Methods: This was a retrospective study performed using a database maintained by a busy syncope unit. Head-up tilt testing was performed using an automated tilt table with Finometer monitoring. A 3 min 70 degrees head-up tilt was performed following 5 min supine. Sitting blood pressure (BP) was measured following 3 min rest. Standing BP was measured within 30 s of assuming the upright posture.

The results of sit-stand testing were compared with head-up tilt testing as a reference standard. Both tests happened within 5 min of each other and patients underwent no intervention between tests.

Results: From a total of 1452 consecutive head-up tilts, we identified 730 with pre-test measures of sitting and standing BP. The mean age of this group was 70.57 years (SD = 15.1), 62% were female.

The sensitivity of sit-stand testing was calculated as 15.5%, specificity as 89.9%, positive predictive value as 61.7%, negative predictive value as 50.2% and the likelihood ratio as 1.6. The area under the Receiver Operator Curve was 0.564.

Conclusion: We have demonstrated that sit-stand testing for orthostatic hypotension has very low diagnostic accuracy. We recommend that the more time-consuming reference standard method of diagnosis be used if the condition is suspected.

Source: QJM, Mar 9, 2009. PMID: 19273552, by Cooke J, Carew S, O’Connor M, Costelloe A, Sheehy T, Lyons D. Clinical Age Assessment Unit, Mid-Western Regional Hospital, Dooradoyle, Limerick, Ireland.

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