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PMID-10996576 – PROOF Trial Salmon Calcitonin Nasal Spray Vertebral Fractures

PMID-10996576 – PROOF Trial Salmon Calcitonin Nasal Spray Vertebral Fractures

Chesnut CH 3rd, Silverman S, Andriano K, et al. A randomized trial of nasal spray salmon calcitonin in postmenopausal women with established osteoporosis: the prevent recurrence of osteoporotic fractures study. PROOF Study Group. Am J Med. 2000;109(4):267-276.

Quick Reference

Property Value
PMID 10996576
DOI 10.1016/S0002-9343(00)00490-3
Year 2000
Journal American Journal of Medicine
Study Type RCT
Evidence Level II
Sample n=1255 postmenopausal women with established osteoporosis
Peptide(s) Studied Calcitonin

Key Findings

  • Nasal salmon calcitonin 200 IU/day reduced the risk of new vertebral fractures by 33% vs placebo (RR 0.67; 95% CI 0.47-0.97; P=0.03)
  • The 100 IU and 400 IU doses did NOT achieve statistical significance — an anomalous dose-response pattern
  • Lumbar spine BMD increased by 1-1.5% with calcitonin nasal spray over 5 years
  • All treatment groups received calcium 1000 mg and vitamin D 400 IU daily
  • The lack of a clear dose-response relationship raised questions about the robustness of the fracture findings
  • Despite limitations, this trial formed the basis for FDA-approved use of nasal calcitonin in postmenopausal osteoporosis

Study Design

Randomized, double-blind, placebo-controlled, multicenter trial over 5 years. 1,255 postmenopausal women with established osteoporosis (at least one vertebral fracture) randomized to nasal spray salmon calcitonin at 100, 200, or 400 IU daily vs placebo. Primary endpoint was new vertebral fractures assessed by lateral spine radiographs. All participants received supplemental calcium and vitamin D.

Limitations

  • Highly criticized for the absence of a dose-response relationship (200 IU worked but 100 and 400 IU did not)
  • Very high dropout rate: only 36% of randomized patients completed the 5-year study
  • Per-protocol analysis was more favorable than intention-to-treat analysis, raising attrition bias concerns
  • No significant reduction in nonvertebral fractures at any dose
  • BMD changes were modest compared to bisphosphonates or teriparatide
  • These methodological issues led some experts to question whether the 33% fracture reduction was a real effect or a statistical artifact

Clinical Relevance

The PROOF trial is historically significant as the largest RCT of calcitonin for osteoporosis, but its controversial results have contributed to calcitonin's declining clinical use. The modest fracture reduction (33% vertebral only), absent dose-response relationship, high dropout rate, and subsequent cancer safety concerns (2013 FDA review) have collectively repositioned calcitonin from a first-line osteoporosis treatment to a niche option primarily valued for its analgesic properties in acute vertebral fracture pain. Modern guidelines rank calcitonin below bisphosphonates, denosumab, and teriparatide for fracture prevention.

Related

#research #RCT #calcitonin #evidence-level-II