As part of their enrollment into the ARIC study, subjects had their BP measurements taken 2 to 5 times in the lying position (90% of participants had ≥ 4 measurements) and after standing (91% participants had ≥ 4 measurements) using a programmable automatic BP cuff. All 5 standing BP measurements (taken at a mean of 28, 53, 76, 100, and 116 seconds after standing) were measured for 7385 out of 11,429 (64.6%) participants. Subjects were asked if he or she “usually gets dizzy on standing up.”
Researchers determined the association between OH and postural change in systolic BP or postural change in diastolic BP with history of dizziness after standing. They also determined the incidence of falls, fracture, syncope, motor vehicle crash, and mortality via a review of hospitalizations and billing for Medicaid and Medicare services. Subjects were followed for a median of 23 years.
Results
Of the entire cohort, 1138 (10%) reported dizziness on standing. Only OH identified at the first BP measurement (mean 28 secs) was associated with a history of dizziness upon standing (odds ratio [OR] = 1.49; 95% confidence interval [CI], 1.18-1.89). Also, it was associated with the highest incidence of fracture, syncope, and death (18.9, 17, and 31.4 per 1000 person-years, respectively).
After adjusting for age, sex, and multiple other cardiovascular risk factors, the risk of falls was significantly associated with OH at BP measurements 1 to 4, but was most strongly associated with BP measurement 2 (taken at a mean of 53 secs after standing) (HR = 1.29; 95% CI, 1.12-1.49), which translates to 13.2 falls per 1000 patient-years. Fracture was associated with OH at measurements 1 (HR = 1.16; 95% CI, 1.01-1.34) and 2 (HR = 1.14; 95% CI, 1.01-1.29). Motor vehicle crashes were associated only with BP measurement 2 (HR = 1.43; 95% CI, 1.04-1.96). Finally, risk of syncope and risk of death were statistically associated with the presence of OH at all 5 BP measurements.
WHAT’S NEW
Earlier OH assessments are more informative than late ones
This study found OH identified within 1 minute of standing to be more clinically meaningful than OH identified after 1 minute. Also, the findings reinforce the relationship between OH and adverse events, including injury and overall mortality. Evaluation for OH performed only at 3 minutes may miss symptomatic OH.
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