METHODS : In this cross-sectional study interview , ECGs and blood samples were collected in a population of adult heroin addicts treated with methadone or buprenorphine on a daily basis .
O O O O O O O O O O O O O O O O O O O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O O B-ChemicalEntity O B-ChemicalEntity O O O O O