Triglyceride Levels and Fracture Risk in Midlife Women: Study of Women's Health Across the Nation (SWAN)

Abstract

Context: Unfavorable lipid levels contribute to cardiovascular disease and may also harm bone health.

Objective: Our objective was to investigate relationships between fasting plasma lipid levels and incident fracture in midlife women undergoing the menopausal transition.

Design and setting: This was a 13-year prospective, longitudinal study of multiethnic women in five US communities, with near-annual assessments.

Participants: At baseline, 2062 premenopausal or early perimenopausal women who had no history of fracture were included.

Exposures: Fasting plasma total cholesterol, triglycerides (TG), low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol at baseline and follow-up visits 1 and 3-7.

Main outcome measure(s): Incident nontraumatic fractures 1) 2 or more years after baseline, in relation to a single baseline level of lipids; and 2) 2-5 years later, in relation to time-varying lipid levels. Cox proportional hazards modelings estimated hazard ratios and 95% confidence interval (CI).

Results: Among the lipids, TG levels changed the most, with median levels increased by 16% during follow-up. An increase of 50 mg/dl in baseline TG level was associated with a 1.1-fold increased hazards of fracture (adjusted hazard ratio, 1.11; 95% CI, 1.04-1.18). Women with baseline TG higher than 300 mg/dl had an adjusted 2.5-fold greater hazards for fractures (95% CI, 1.13-5.44) than women with baseline TG lower than 150 mg/dl. Time-varying analyses showed a comparable TG level-fracture risk relationship. Associations between total cholesterol, low-density lipoprotein cholesterol, or high-density lipoprotein cholesterol levels and fractures were not observed.

Conclusions: Midlife women with high fasting plasma TG had an increased risk of incident nontraumatic fracture. Secondary Abstract: Midlife women with fasting plasma triglyceride (TG) of at least 300 mg/dl had 2.5-fold greater hazards of fracture in 2 years later and onward, compared to those with TG below 150 mg/dl, in a multiethnic cohort. Time-varying analyses revealed comparable results.

Figure 1.

Flow diagram of 2062 women who were included in the current study from the Study of Women's Health Across the Nation.

Figure 2.

Counts of incident nontraumatic fracture at each near-annual visit. All nontraumatic fractures excluded those at the face, toes, or digits. Incident nontraumatic fractures were self-reported fractures not related to a fall from a height above the ground greater than 6 inches, a motor vehicle accident, moving fast (like running, bicycling or skating), playing sports, or something heavy fell or struck. Between visits 7 and 13, self-reported fractures were further confirmed by medical records review: 74% of all (109 of 147) nontraumatic fractures were confirmed in medical records.