The CDC VITAL-EQA program, external quality assurance for serum retinol, 2003–2006

BackgroundWith approximately 127 million preschool children currently suffering from vitamin A deficiency globally, it is important for affected countries to have the capacity to determine the prevalence of vitamin A deficiency and to monitor the progress being made to eradicate this problem through supplementation and fortification programs. The VITamin A Laboratory-External Quality Assurance program (VITAL-EQA) administered by the US Centers for Disease Control and Prevention was developed in 2003 to help predominantly less developed countries to assess and improve their ability to accurately and precisely measure serum retinol, and more recently other nutritional indicators.MethodsTwice each year, laboratories test serum samples in duplicate over the course of 3 days. Results are returned and troubleshooting is performed if needed.ResultsMeasurement accuracy improved for 2 laboratories and declined for 2 laboratories, whereas the remainder of laboratories participating in > 1 round showed consistently acceptable performance. Precision improved for 7 laboratories, declined for 4 laboratories, and remained at ≤ 5% coefficient of variation for the rest of the participants.ConclusionsThis program is a valuable tool for the assessment and improvement of retinol testing in laboratories throughout the world.