Relationship between bone quantitative ultrasound and mortality: a prospective study

Abstract

In a cohort of 5,201 women [72.3 +/- 5.3 years] from 58 primary care centers in Spain, followed for three years, no relationship between heel QUS parameters and overall mortality was found. However, a significant relationship between a low speed of sound (SOS) and vascular mortality was observed.

Introduction: An inverse relationship between mortality and bone mineral density measured by dual-energy absorption densitometry or quantitative bone ultrasound (QUS) has been described. The aim of the present study was to test this relationship in the ECOSAP cohort, a 3-year prospective study designed to assess the ability of heel QUS and clinical risk factors to predict non-vertebral fracture risk in women over 64.

Methods: A cohort of 5,201 women [72.3 +/- 5.3 years] was studied. QUS was assessed with the Sahara(R) bone sonometer. Women attended follow-up visits every 6 months. Physicians recorded if the patient died and cause of death. Hazard rates (HR) of all-cause and vascular mortality per one standard deviation reduction in QUS parameters were determined.

Results: One hundred (1.9%) women died during a median of 36.1 months follow-up, for a total of 14,999 patient-years, 42 because of vascular events (both cardiovascular and cerebrovascular). After adjusting for age, none of the QUS variables showed statistically significant differences between the patients who died and the survivors. In the final multivariate model, adjusted for age, current thyroxine and hypoglycaemic drug use, chronic obstructive pulmonary disease and decreased visual acuity, SOS was marginally non-significant: (HR: 1.19; 0.97-1.45). However, each 1 SD reduction in SOS was associated with a 39% increase in vascular mortality (HR: 1.39; 1.15-1.66).

Conclusions: In our cohort, SOS was related with vascular mortality, but not overall mortality.