Clinical correlates of vitamin D deficiency in established psychosis

Cross-sectional analysis of baseline data from IMPaCT, a randomized controlled trial in psychosis; 324 community-dwelling adults in England with established psychosis; mean age 43.6 years; 59.6% male; diagnoses included schizophrenia spectrum and other psychoses; recruited via community mental health teams.

Mean 25-OHD level 12.4 ng/mL; 49% deficient (<10 ng/mL); 14% sufficient (>30 ng/mL). After adjusting for age, sex, ethnicity and season, 25-OHD inversely correlated with waist circumference (r=-0.220), BMI (-0.163), triglycerides (-0.160), total cholesterol (-0.144), fasting glucose (-0.191), HbA1c (-0.183), and CRP (-0.211). Higher 25-OHD quartiles linked to lower metabolic syndrome prevalence (highest quartile ~20.5% vs lower quartiles 39.1%, 48.3%, 43.1%). Hours spent outdoors positively correlated with 25-OHD (r=0.140); low-intensity activity associated with lower 25-OHD than moderate/high activity (p=0.002). Vitamin D supplementation did not meaningfully raise 25-OHD levels in this sample. Vitamin D deficiency is common in established psychosis and associates with increased cardiometabolic risk; larger randomized trials are needed to determine whether screening and supplementation improve cardiovascular health and mortality in psychosis.

Cross-sectional design; cannot infer causality. Potential residual confounding and selection bias. 25-OHD measured by immunoassay with potential misclassification; lack of detailed data on supplementation; findings may not generalize beyond English, community-dwelling adults with established psychosis.