Plenary Poster 29th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2019

Effects of calcium supplementation on long-term change in abdominal aortic calcification in older women: analysis of a 5 year double-blind randomised controlled trial (#85)

Joshua R Lewis 1 2 3 , Wai H Lim 3 4 , John T Schousboe 5 , Elizabeth Byrnes 6 , Richard J Woodman 7 , Jonathan M Hodgson 1 3 , Kun (Kathy) Zhu 3 8 , Peter L Thompson 9 , Douglas P Kiel 10 , Richard L Prince 3 8
  1. Edith Cowan University, Perth, WA, Australia
  2. Centre for Kidney Research, School of Public Health, University of Sydney, Sydney, NSW, AUSTRALIA
  3. Medical School, University of Western Australia, PERTH, WA, AUSTRALIA
  4. Department of Renal Medicine, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  5. Park Nicollet Osteoporosis Center and HealthPartners Institute, Minneapolis, MA, US
  6. PathWest, PERTH, WA, AUSTRALIA
  7. Flinders Centre for Epidemiology and Biostatistics, Flinders University, Adelaide, SA, AUSTRALIA
  8. Endocrinology and Diabetes, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  9. Cardiology, Sir Charles Gairdner Hospital, PERTH, WA, AUSTRALIA
  10. Hinda and Arthur Marcus Institute for Aging Research, Hebrew SeniorLife, Boston, MA, US

Concerns have been raised that commonly used calcium supplements may increase the risk of myocardial infarction (MI), possibly by increasing arterial calcification. Using data from the Calcium Intake Fracture Outcome Study, a 5-year double-blind, placebo controlled trial of 1.2g of elemental calcium in the form of calcium carbonate in 1,460 older women over 70 years, our objective was to determine if calcium supplements increased progression of abdominal aortic calcification (AAC) compared to placebo. Lateral spine images captured at the time of bone density testing were scored using the AAC24 semi-quantitative method by an experienced investigator (JTS) blinded to the clinical data. 904 women assigned to placebo or calcium had valid assessments for AAC in 1998-1999 and 2003-2004 (end of trial). The mean age of the women at baseline was 74.9 ± 2.6 years and the median and interquartile range of AAC24 was 2 [0-4]. There was no difference in the AAC24 change in the intention-to-treat (ITT) or the per-protocol (PP) analyses (n=626 participants taking ≥80% of their tablets) between the calcium vs. placebo groups (Table 1), with similar findings after adjustment for age, dietary calcium and cardiovascular risk factors (p-difference 0.659 and 0.464, respectively). When looking at secondary outcomes, 301/904 (33.3%) women had AAC24 progression of 2 or greater in ITT (calcium 34.3% vs placebo 32.3%, Fisher’s exact p-value=0.572) and PP analyses (calcium 37.0% vs. placebo 30.5%, p-value=0.091). In women with no AAC (AAC24=0, n=180) that developed any AAC (AAC24 progression ≥1, n=51) there was no difference between groups in ITT (calcium 21.7% vs. placebo 34.0%, p-value=0.071). In PP analysis fewer women randomized to calcium supplements developed AAC (calcium 23.0% vs. placebo 42.4%, p-value=0.032). In conclusion, this study did not identify evidence that long-term calcium supplementation increase the progression of abdominal aortic calcification.

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