Oral Presentation ANZBMS-MEPSA-ANZORS 2022

Tracking of vitamin D status and its association with bone loss in middle-aged Australians: Busselton Healthy Ageing Study (#209)

Kun (Kathy) Zhu 1 2 , Michael Hunter 3 4 , Jennie Hui 3 4 5 , Kevin Murray 4 , Alan James 1 6 , Ee Mun Lim 2 5 , John Walsh 1 2
  1. Medical School, University of Western Australia, Perth, WA, Australia
  2. Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Perth, WA, Australia
  3. Busselton Population Medical Research Institute, Busselton, WA, Australia
  4. School of Population and Global Health, University of Western Australia, Perth, WA, Australia
  5. Department of Clinical Biochemistry, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Perth, WA, Australia
  6. Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Perth, WA, Australia

Context: Little is known on the stability of vitamin D status in middle age and whether its tracking patterns associate with bone loss. We evaluated the tracking of serum 25-hydroxyvitamin D (25OHD) measured 6 years apart, and its association with bone mineral density (BMD) in participants of the Busselton Healthy Ageing study aged 46-70 years at baseline.

Methods: Out of the 5017 individuals recruited, 3386 (1871 females) who had serum 25OHD and DXA BMD assessments at both baseline and ~6 years were included in the analysis. The tracking patterns of serum 25OHD were defined as: low/decreasing (both measures <60 nmol/L or moved to lower category over time, n=1103), increasing (moved to higher category over time, n=549), medium (both measures 60-75 nmol/L, n=335) and high (both measures ≥75 nmol/L, n=1399).

Results: Mean season-corrected serum 25OHD was 81.3±22.7 and 78.8±23.1 nmol/L at baseline and 6 years, respectively, and showed moderate correlation (Pearson’s correlation coefficient: 0.568; intraclass correlation coefficient: 0.724). Significant predictors of change in serum 25OHD concentration over 6 years included baseline 25OHD, sex, change in BMI and vitamin D supplement use at follow-up. The high vitamin D status group had significantly higher femoral neck and total hip BMD at baseline than the other three groups (by 0.011-0.018 g/cm2). The low/decreasing vitamin D status group had significantly greater decline in femoral neck and total hip BMD (by 0.005-0.008 g/cm2) over the follow-up period compared with the increasing, medium and high vitamin D status groups after adjustment for sex and baseline BMD values, age, BMI, vitamin D supplement and lifestyle factors (all P<0.05) (Table 1).

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Conclusion: Serum 25OHD measured 6 years apart showed moderate tracking. Individuals with consistently low or declining vitamin D status had greater bone loss during the follow-up period and could be the target for intervention.