Low blood pressure levels for fall injuries in older adults: the Health,Aging and Body Composition Study

Fall injuries cause morbidity and mortality in older adults. We assessed if low blood pressure (BP) is associated with fall injuries, including sensitivity analyses stratified by antihypertensive medications, in community-dwelling adults from the Health, Aging and Body Composition Study (N = 1819; age 76.6 ± 2.9 years; 53% women; 37% black). Incident fall injuries (N = 570 in 3.8 ± 2.4 years) were the first Medicare claims event from clinic visit (7/00–6/01) to 12/31/08 with an ICD-9 fall code and non-fracture injury code, or fracture code with/without a fall code. Participants without fall injuries (N = 1249) were censored over 6.9 ± 2.1 years. Cox regression models for fall injuries with clinically relevant systolic BP (SBP; ≤ 120, ≤ 130, ≤ 140, > 150 mmHg) and diastolic BP (DBP; ≤ 60, ≤ 70, ≤ 80, > 90 mmHg) were adjusted for demographics, body mass index, lifestyle factors, comorbidity, and number and type of medications. Participants with versus without fall injuries had lower DBP (70.5 ± 11.2 vs. 71.8 ± 10.7 mmHg) and used more medications (3.8 ± 2.9 vs. 3.3 ± 2.7); all P < 0.01. In adjusted Cox regression, fall injury risk was increased for DBP ≤ 60 mmHg (HR = 1.25; 95% CI 1.02–1.53) and borderline for DBP ≤ 70 mmHg (HR = 1.16; 95% CI 0.98–1.37), but was attenuated by adjustment for number of medications (HR = 1.22; 95% CI 0.99–1.49 and HR = 1.12; 95% CI 0.95–1.32, respectively). Stratifying by antihypertensive medication, DBP ≤ 60 mmHg increased fall injury risk only among those without use (HR = 1.39; 95% CI 1.02–1.90). SBP was not associated with fall injury risk. Number of medications or underlying poor health may account for associations of low DBP and fall injuries.