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What are the characteristics of vitamin D metabolism in opioid dependence? An exploratory longitudinal study in Australian primary care

13 Jan 2018

Objective

Compare vitamin D levels in opioid dependence and control population and adjust for relevant confounding effects. Nuclear hormone receptors (including the vitamin D receptor) have been shown to be key transducers and regulators of intracellular metabolism and comprise an important site of pathophysiological immune and metabolic dysregulation potentially contributing towards pro-ageing changes observed in opioid-dependent patients (ODPs).

Design

Longitudinal prospective comparing ODPs with general medical controls (GMCs).

Setting

Primary care.

Participants

Prospective review comparing 1168 ODP (72.5% men) and 415 GMC (51.6% men, p<0.0001). Mean ages were 33.92±0.31 (mean±SEM) and 41.22±1.32 years, respectively (p<0.0001). Opioid use in the ODP has been previously reported and shown to be typical.

Interventions

Nil. Observational study only.

Primary and secondary outcomes

Serum vitamin D levels and relevant biochemical parameters.

Results

Vitamin D levels were higher in the ODP (70.35±1.16 and 57.06±1.81 nmol/L, p<0.0001). The difference in ages between the two groups was handled in an age-matched casecontrol subanalysis and also by multiple regression. Sexes were analysed separately. The age:status (or age:time:status) was significant in casecontrol, cross-sectional and longitudinal analyses in both sexes (p<0.05). Modelled vitamin D was 62.71 vs 57.81 nmol/L in the two groups. Time-dependent mixed-effects models quadratic in age outperformed linear-only models (p=0.0377). ODP vitamin D was shown to vary with age and to correlate with alanine aminotransferase establishing it as a biomarker of age in this group. Hepatitis C seronegativity was significant in regression models (from p=0.0015).

Conclusion

Vitamin D was higher in ODP in both sexes in bivariate, cross-sectional, casecontrol and longitudinal analyses and was robust to the inclusion of metabolic and immune biomarkers. That Hepatitis C seronegativity was significant suggests opioid dependence has an effect beyond simply that of its associated hepatitides. This finding may relate to the accelerated ageing process previously described in opioid dependence.

Click here to view the full article which appeared in BMJ Open