Strict training modules were designed and used to train interviewers and other staff. A vigorous quality assurance program was implemented to ensure the quality of data collection and laboratory examinations. After selecting the eligible individuals, all steps were done at the door. A team consisting of health care professionals recorded demographic and health information in a checklist and carried out the field examinations by standardized and calibrated instruments. Weight, height, and waist circumference were measured according to a standard protocol (5 ), and BMI was computed. Blood pressure was measured three times by using a digital sphygmomanometer (M7 Omron). The means of the second and third measurements were used in the analysis.
Trained laboratory technicians obtained fasting (10–12 h) venous blood samples and transferred them in cold boxes to a referral laboratory in each province that was at most 4 h away from the sampling site. In addition, for protecting blood glucose concentrations from glycolysis, the anticoagulant sodium fluoride was added to the collection vial. The blood samples were centrifuged, and sera were kept frozen at −20°C before being transferred to the National Reference Laboratory, a WHO-collaborating center in Tehran. We measured glucose with the glucose oxidase/peroxidase-4-aminophenazone-phenol method and triglycerides were measured using glycerol-3-phosphate oxidase-peroxidase aminophenazone (Randox). HDL cholesterol was determined after dextran sulfate-magnesium chloride precipitation of non–HDL cholesterol (7 (link)). Uniform testing kits from the same batch number (Pars Azmoun Company) were used to test the samples. Of all samples, 10% were rechecked by the National Reference Laboratory as a quality assurance measure. The coefficient of variation was <5% for all laboratory measurements.
Trained laboratory technicians obtained fasting (10–12 h) venous blood samples and transferred them in cold boxes to a referral laboratory in each province that was at most 4 h away from the sampling site. In addition, for protecting blood glucose concentrations from glycolysis, the anticoagulant sodium fluoride was added to the collection vial. The blood samples were centrifuged, and sera were kept frozen at −20°C before being transferred to the National Reference Laboratory, a WHO-collaborating center in Tehran. We measured glucose with the glucose oxidase/peroxidase-4-aminophenazone-phenol method and triglycerides were measured using glycerol-3-phosphate oxidase-peroxidase aminophenazone (Randox). HDL cholesterol was determined after dextran sulfate-magnesium chloride precipitation of non–HDL cholesterol (7 (link)). Uniform testing kits from the same batch number (Pars Azmoun Company) were used to test the samples. Of all samples, 10% were rechecked by the National Reference Laboratory as a quality assurance measure. The coefficient of variation was <5% for all laboratory measurements.
