K. A. Achtymichuk, J. A. Johnson, J. K. Minhas-Sandhu, M. Lin, and D. T. Eurich, “DEVELOPMENT AND VALIDATION OF AN INDEX SCORE TO ADJUST FOR HEALTHY USER BIAS IN OBSERVATIONAL STUDIES”, J Popl Ther Clin Pharmacol, vol. 24, no. 3, pp. e79-e89, Nov. 2017.