@article {Reecee016806, author = {Albert Stuart Reece and Gary Kenneth Hulse}, title = {What are the characteristics of vitamin D metabolism in opioid dependence? An exploratory longitudinal study in Australian primary care}, volume = {8}, number = {1}, elocation-id = {e016806}, year = {2018}, doi = {10.1136/bmjopen-2017-016806}, publisher = {British Medical Journal Publishing Group}, abstract = {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{\textpm}0.31 (mean{\textpm}SEM) and 41.22{\textpm}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{\textpm}1.16 and 57.06{\textpm}1.81 nmol/L, p\<0.0001). The difference in ages between the two groups was handled in an age-matched case{\textendash}control subanalysis and also by multiple regression. Sexes were analysed separately. The age:status (or age:time:status) was significant in case{\textendash}control, 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, case{\textendash}control 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.}, issn = {2044-6055}, URL = {https://bmjopen.bmj.com/content/8/1/e016806}, eprint = {https://bmjopen.bmj.com/content/8/1/e016806.full.pdf}, journal = {BMJ Open} }