Prevalent vertebral deformity independently increases incident vertebral fracture risk in middle-aged and elderly Japanese women: the Japanese Population-based Osteoporosis (JPOS) Cohort Study.
CONCLUSIONS
Prevalent vertebral deformity increases incident vertebral fracture risk according to studies focusing primarily on Caucasian elderly populations. We report a 3-fold increase in this risk in a population-based cohort of Japanese women after adjusting for subject propensity for having vertebral deformities. This relationship tended to be stronger in middle-aged women.


BACKGROUND
Evidence on increased risk of incident vertebral fractures associated with vertebral deformity in middle-aged women is limited. We aimed to evaluate this risk in a population-based cohort of Japanese women.


METHODS
We followed 712 women aged 50-79 years at baseline randomly selected from 3 municipalities in Japan for 6 years. McCloskey-Kanis criteria identified vertebral deformities on X-ray absorptiometric images. At follow-up, vertebra with > or = 20% height reduction from baseline were considered incident fractures. Rate ratio (RR) of incident fracture for prevalent vertebral deformities was calculated using the Poisson regression equation adjusted for propensity of having vertebral deformities based on potential risk factors.


RESULTS
Vertebral fractures occurred in 73 women (10.3%). Crude RR of vertebral deformity-associated fracture was 4.63 [95% confidence interval (CI), 3.04-7.04] and decreased to 2.96 (95% CI, 1.77-4.94) after propensity score adjustment. Adjusted RR was generally greater in younger women at 7.19 (95% CI, 1.04-49.6), 3.19 (95% CI, 1.27-7.97), and 2.34 (95% CI, 1.33-4.11) for women aged 50-59, 60-69, and 70-79 years, respectively (p = 0.0527 for those aged 50-59 vs 70-79).


CONCLUSIONS
Vertebral deformity was associated with a 3-fold increase in subsequent vertebral fracture risk in Japanese women, and this association was stronger in middle-aged women.
Kadowaki
E
E
Department of Public Health, Kinki University School of Medicine, 377-2 Oono-higashi, Osaka-Sayama 589-8511, Japan.
Tamaki
J
J
Iki
M
M
Sato
Y
Y
Chiba
Y
Y
Kajita
E
E
Kagamimori
S
S
Kagawa
Y
Y
Yoneshima
H
H
D000367:Age Factors; D000368:Aged; D015519:Bone Density; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D058866:Osteoporotic Fractures / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D013121:Spinal Curvatures / Q000150:complications* / Q000453:epidemiology; D016103:Spinal Fractures / Q000453:epidemiology / Q000209:etiology*