Tran, BichArmstrong, Bruce KMcGeechan, KevinEbeling, Peter REnglish, Dallas RKimlin, Michael Gvan der Pols, Jolieke, CVenn, AlisonGebski, ValWhiteman, David CWebb, Penelope MNeale, Rachel ELucas, Robyn2013-11-052013-11-051365-2265http://hdl.handle.net/1885/10689OBJECTIVE: There has been a dramatic increase in vitamin D testing in Australia in recent years, prompting calls for targeted testing. We sought to develop a model to identify people most at risk of vitamin D deficiency. Design and Participants: This is a cross-sectional study of 644 60- to 84-year-old participants, 95% of whom were Caucasian, who took part in a pilot randomized controlled trial of vitamin D supplementation. MEASUREMENTS: Baseline 25(OH)D was measured using the Diasorin Liaison platform. Vitamin D insufficiency and deficiency were defined using 50 and 25 nmol/l as cut-points, respectively. A questionnaire was used to obtain information on demographic characteristics and lifestyle factors. We used multivariate logistic regression to predict low vitamin D and calculated the net benefit of using the model compared with ‘test-all’ and ‘test-none’ strategies. RESULTS: The mean serum 25(OH)D was 42 (SD 14) nmol/1. Seventy-five per cent of participants were vitamin D insufficient and 10% deficient. Serum 25(OH)D was positively correlated with time outdoors, physical activity, vitamin D intake and ambient UVR, and inversely correlated with age,BMI and poor self-reported health status. These predictors explained approximately 21% of the variance in serum 25 (OH)D. The area under the ROC curve predicting vitamin D deficiency was 0 82. Net benefit for the prediction model was higher than that for the ‘test-all’ strategy at all probability thresholds and higher than the ‘test-none’ strategy for probabilities up to 60%. CONCLUSION: Our model could predict vitamin D deficiency with reasonable accuracy, but it needs to be validated in other populations before being implemented.NHMRC (National Health and Medical Research Council of Australia)10 pageshttp://www.sherpa.ac.uk/romeo/issn/0300-0664/ Author can archive pre-print (ie pre-refereeing); subject to Restrictions below, author can archive post-print (ie final draft post-refereeing) - restrictions - If signed CTA, only allowed with written permission and 0 to 24 months depending on journal and funding agency requirements; author cannot archive publisher's version/PDF. From Sherpa/Romeo as at 4/11/13.circulating 25-hydroxyvitamin Dcancer riskpancreatic-cancerdeterminantspopulationtrialmodelsUSmen2013-1110.1111/cen.122032015-12-11