Cerebral Hypoperfusion And Future Falls Risk Among Community Dwelling Older Adults with Orthostatic Hypotension

Background Falls occur in approximately 33% of those over 65 annually, with 10-20% resulting in injury or hospitalisation. Orthostatic Hypotension (OH) characterised by significant blood pressure (BP) drops upon standing is frequently identified in those with unexplained falls (UF). Cerebral hypoperfusion is regarded as the mechanism by which OH contributes to falls risk. However, work looking at the direct interaction between OH, cerebral perfusion and falls is lacking. Methods Near Infrared Spectroscopy (NIRS) derived frontal lobe cerebral oxygenation (reported as tissue saturation index (TSI)) and continuous beat-to-beat BP by finometer were measured in parallel during active standing among participants aged ≥55 at wave3 of TILDA (n=2478). OH, was defined as persisting systolic BP drop ≥20mmHg and/or diastolic BP drop ≥10mmHg at 30, 60 and 90seconds post standing. TSI drop from baseline ≥75th centile at 30seconds informed the “greater TSI drop” variable for longitudinal analysis. Multilevel linear regression models assessed the association between change in TSI from baseline and OH. Multilevel logistic regression models assessed the longitudinal relationship between OH, cerebral perfusion and future UF at 4years follow up (waves 4-5). Results Twenty percent had OH and were more likely to be older and have cardiovascular disease. TSI drops from baseline after standing were significantly greater in those with OH at 30 (beta=0.32 [CI 0.15-0.49]; p<0.001), 60 (beta=0.41 [CI 0.23-0.6]; p<0.001), and 90 (beta=0.46 [CI 0.27-0.65]; p<0.001) seconds in fully adjusted models. After robust adjustment, combination of OH with greater TSI drops was strongly associated with future UF (Odds Ratio (OR) 2.23 [CI 1.35-3.69]; p=0.002), while OH and lower TSI drops were not (OR 1.27 [CI 0.87-1.85]; p=0.216). Conclusion These novel findings confirm that degree of cerebral hypoperfusion on standing informs risk of future UF in those with OH and has important clinical implications for the risk assessment of older people presenting with falls.