Clinical clustering of eight orthostatic haemodynamic patterns in The Irish Longitudinal Study on Ageing (TILDA)

Abstract

INTRODUCTION: Orthostatic hypotension (OH) can be assessed with non-invasive continuous beat-to-beat haemodynamic monitoring during active stand (AS) testing; this yields large volumes of data outside the scope of the traditional OH definition. I explored clinical associations of different AS patterns in participants from Wave 1 of The Irish Longitudinal Study on Ageing (TILDA). METHODS: AS patterns were generated based on three sequential binary BP features: drop ≥40/20mmHg SBP/DBP within 10s post-stand (“immediate deficit”), failure to return to within 20/10mmHgS BP/DBP of supine level at 40s after standing (“stabilisation deficit”), and drop ≥20/10mmHg SBP/DBP between >40 and 120s post-stand (“late deficit”). Eight AS groups (for SBP and DBP each) resulted from combining the presence/absence of these three features. The groups were cross-sectionally characterised, and their ability to independently predict orthostatic intolerance (OI), falls or syncope in the past year, was evaluated using multivariable logistic regression models.The heart rate features of the eight SBP/DBP groups were then analysed including: resting heart rate (RHR), meanHR, maxHR, deltaHR and heart rate recovery. RESULTS4899 participants were included, with a mean age of 61 and of whom 55% were female. The largest group was the one with no deficits (SBP: 68% vs DBP: 49.41%). In both SBP and DBP groups, older age was associated with stabilisation deficit and late deficits were seen in groups with higher proportions of beta blockers and psychotropic medications. There were higher rates of cardiovascular risk factors/disease in the DBP groups.In both SBP and DBP groups, regression models identified independent associations between OI and three immediate-deficit groups; associations became stronger as more deficits were present.There was a significant association between falls history and the three-deficit group (SBP: OR 1.54, 95% CI: 1.15-2.07, p=0.004, DBP: OR1.56, 95% CI: 1.18-2.07, p=0.002). Groups 1 and 3 have the lowest RHR and Group 8 has the quickest HRR10_20 recovery (-6.69, -6.81)when defined by either SBP or DBP criteria. CONCLUSIONS: The accumulation of AS deficits was reflective of a frailer and more multimorbid population and was associated with higher risk of OI and falls history. During an AS the recovery pattern after the drop is as important, if not more than the initial BP drop alone.The current practice of using SBP or DBP to identify OH may result in two OH populations with different underlying pathophysiology being grouped together.