Hyperkyphosis Predicts Mortality Independent of Vertebral Osteoporosis in Older Women

doi:10.1059/0003-4819-150-10-200905190-00005

Hyperkyphosis Predicts Mortality Independent of Vertebral Osteoporosis in Older Women

Deborah M. Kado, MD, MS;
Li-Yung Lui, MA, MS;
Kristine E. Ensrud, MD, MPH;
Howard A. Fink, MD, MPH;
Arun S. Karlamangla, PhD, MD;
Steven R. Cummings, MD; and
for the Study of Osteoporotic Fractures

From the University of California, Los Angeles, Los Angeles, California; California Pacific Medical Center, San Francisco, California; and Minneapolis Veterans Affairs Medical Center, Minneapolis, Minnesota.

Abstract

Background: Excessive kyphosis may be associated with earlier mortality, but previous studies have not controlled for clinically silent vertebral fractures, which are a known mortality risk factor.

Objective: To determine whether hyperkyphosis predicts increased mortality independent of vertebral fractures.

Design: Prospective cohort study.

Setting: Four clinical centers in Baltimore County, Maryland; Portland, Oregon; Minneapolis, Minnesota; and the Monongahela Valley, Pennsylvania.

Patients: 610 women, age 67 to 93 years, from a cohort of 9704 women recruited from community-based listings between 1986 and 1988.

Measurements: Kyphosis was measured by using a flexicurve. Prevalent radiographic vertebral fractures at baseline were defined by morphometry, and mortality was assessed during an average follow-up of 13.5 years.

Results: In age-adjusted models, each SD increase in kyphosis carried a 1.14-fold increased risk for death (95% CI, 1.02 to 1.27; P = 0.023). After adjustment for age and other predictors of mortality, including such osteoporosis-related factors as low bone density, moderate and severe prevalent vertebral fractures, and number of prevalent vertebral fractures, women with greater kyphosis were at increased risk for earlier death (relative hazard per SD increase, 1.15 [CI, 1.01 to 1.30]; P = 0.029). On stratification by prevalent vertebral fracture status, only women with prevalent fractures were at increased mortality risk from hyperkyphosis, independent of age, self-reported health, smoking, spine bone mineral density, number of vertebral fractures, and severe vertebral fractures (relative hazard per SD increase, 1.58 [CI, 1.06 to 2.35]; P = 0.024).

Limitation: The study population included only white women.

Conclusion: In older women with vertebral fractures, hyperkyphosis predicts an increased risk for death, independent of underlying spinal osteoporosis and the extent and severity of vertebral fractures.

Primary Funding Source: National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Institute on Aging.

Article and Author Information

Grant Support: By the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging under the following grant numbers: AG05407, AR35582, AG05394, AR35584, AR35583, R01 AG005407, R01 AG027576-22, 2 R01 AG005394-22A1, 2 R01 AG027574-22A1, 1K12AG01004, and 1 R01 AG024246.
Potential Financial Conflicts of Interest: None disclosed.
Reproducible Research Statement: Study protocol and data set: Available at http://sof.ucsf.edu/Interface/. Statistical code: Available from Ms. Lui (e-mail, LLui{at}sfcc-cpmc.net).
Requests for Single Reprints: Deborah M. Kado, MD, MS, MacDonald Research Laboratory, 675 Charles E. Young Drive South, Room 2741, Los Angeles, CA 90095-1759; e-mail, dkado{at}mednet.ucla.edu.
Current Author Addresses: Dr. Kado: MacDonald Research Laboratory, 675 Charles E. Young Drive South, Room 2741, Los Angeles, CA 90095-1759.
Ms. Lui and Dr. Cummings: San Francisco Coordinating Center, 185 Berry Street, Lobby 5, Suite 5700, San Francisco, CA 94107.
Dr. Ensrud: Minneapolis Veterans Affairs Medical Center, One Veterans Drive, General Internal Medicine (111-0), Minneapolis, MN 55417.
Dr. Fink: Geriatric Research Education and Clinical Center, 11-G, Veterans Affairs Medical Center, One Veterans Drive, Minneapolis, MN 55417.
Dr. Karlamangla: 10945 Le Conte Avenue, Suite 2339, Los Angeles, CA 90095.
Author Contributions: Conception and design: D.M. Kado, S.R. Cummings.
Analysis and interpretation of the data: D.M. Kado, L.Y. Lui, H.A. Fink, A.S. Karlamangla.
Drafting of the article: D.M. Kado.
Critical revision of the article for important intellectual content: D.M. Kado, L.Y. Lui, K.E. Ensrud, H.A. Fink, A.S. Karlamangla.
Final approval of the article: D.M. Kado, L.Y. Lui, K.E. Ensrud, H.A. Fink, A.S. Karlamangla.
Provision of study materials or patients: S.R. Cummings.
Statistical expertise: L.Y. Lui, A.S. Karlamangla.
Obtaining of funding: D.M. Kado, K.E. Ensrud.
Administrative, technical, or logistic support: D.M. Kado.
Collection and assembly of data: K.E. Ensrud.