Meta-analyses of therapies for postmenopausal osteoporosis. VI. Meta-analysis of calcitonin for the treatment of postmenopausal osteoporosis.
OBJECTIVE
To review the effect of calcitonin on bone density and fractures in postmenopausal women.


METHODS
We searched MEDLINE and EMBASE from 1966 to 2000 and examined citations of relevant articles and the proceedings of international osteoporosis meetings. We contacted osteoporosis investigators to identify additional studies and primary authors for unpublished data.


METHODS
We included 30 studies that randomized women to calcitonin or an alternative (placebo or calcium and/or vitamin D) and measured bone density or fracture incidence for at least 1 yr.


METHODS
For each trial, three independent reviewers assessed the methodological quality and abstracted data.


RESULTS
Calcitonin reduced the incidence of vertebral fractures, with a pooled relative risk (RR) of 0.46 [95% confidence interval (CI) 0.25-0.87, P = 0.02, n = 1404, 4 trials]. However, the RR from the one relatively large randomized controlled trial (RCT) was 0.79 (95% CI 0.62-1.00, P = 0.05, n = 1108). For nonvertebral fractures, the pooled RR was 0.52 (95% CI 0.22-1.23, P = 0.14, n = 1481, 3 trials). Once again, the single large trial showed a less impressive effect than the smaller trials (RR 0.80, 95% CI 0.59-1.09, P = 0.16, n = 1245). For bone density of the lumbar spine, the pooled weekly dose of 250 to 2800 IU per week resulted in significant increase in the weighted mean difference (WMD) of 3.74 (2.04-5.43, P < 0.01, n = 2260, 24 trials). The combined forearm showed a similar effect, with a WMD of 3.02 (95% CI 0.98-5.07, P < 0.01, n = 468, 9 trials). At the femoral neck, the pooled weighted mean difference showed a nonsignificant trend toward benefit, WMD 3.80 (95% CI -0.32-7.91, P = 0.07, 9 trials, n = 513). Methodologically weaker studies tended to show greater effects on bone density, and the lumbar spine results suggested the possibility of publication bias.


CONCLUSIONS
Calcitonin likely increases bone density in postmenopausal women predominantly at the lumbar spine and forearm for weekly doses of greater than 250 IU, although the true effect may be smaller than the pooled estimate would suggest. Calcitonin likely reduces the risk of vertebral fracture; its effect on nonvertebral fracture remains uncertain.
Ann
A
Cranney
Peter
P
Tugwell
Nicole
N
Zytaruk
Vivian
V
Robinson
Bruce
B
Weaver
Beverley
B
Shea
George
G
Wells
Jonathan
J
Adachi
Lisa
L
Waldegger
Gordon
G
Guyatt
D002116:Calcitonin / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic
D002116:Calcitonin