Blood pressure, gait speed, and mortality in very old individuals: a population-based cohort study.

OBJECTIVES

Clinical trials and observational studies have produced contradictory results regarding the association of blood pressure (BP) and mortality in people aged 80 years or older. Gait speed at usual pace has been shown to moderate this association in a population of noninstitutionalized people aged 65 years or older. The aims of this study were to investigate the association of BP with all-cause mortality in a representative sample of people aged 85 years or older and to assess whether gait speed moderates this association.

DESIGN, SETTING, AND PARTICIPANTS: A total of 806 participants in the population-based prospective Umeå 85+/GERDA study aged 85, 90, and 95 years or older.

MEASUREMENTS

Gait speed at usual pace was measured over 2.4 m. The main outcome was hazard ratios (HRs) for all-cause mortality according to systolic and diastolic BP categories in the total sample and in faster-walking (≥0.5 m/s, n = 312) and slower-walking (<0.5 m/s, n = 433) subcohorts; the latter also included habitually nonwalking participants. Comprehensive adjustments were made for sociodemographic and clinical characteristics associated with death.

RESULTS

Mean age and baseline systolic and diastolic BP were 89.6 ± 4.6 years, 146.8 ± 23.9 mm Hg, and 74.8 ± 11.1 mm Hg, respectively. Most (n = 561 [69%]) participants were women, 315 (39%) were care facility residents, and 566 (70%) were prescribed BP-lowering drugs. Within 5 years, 490 (61%) participants died. In the total sample and slower-walking subcohort, systolic BP appeared to be inversely associated with mortality, although not independent of adjustments. Among faster-walking participants, mortality risk after adjustment was more than 2 times higher in those with systolic BP of 140 to 149 mm Hg (HR = 2.25, 95% confidence interval [CI] = 1.03-4.94) and 165 mm Hg or higher (HR = 2.13, 95% CI = 1.01-4.49), compared with systolic BP of 126 to 139 mm Hg. Mortality risk was also independently higher in faster-walking participants with diastolic BP higher than 80 mm Hg, compared with diastolic BP of 75 to 80 mm Hg (HR = 1.76, 95% CI = 1.07-2.90).

CONCLUSION

The gait speed threshold of 0.5 m/s may be clinically useful for the distinction of very old people with and without increased all-cause mortality risk due to elevated systolic and diastolic BP.