Fig. 1From: Factors associated with refusal of preventive therapy after initial willingness to accept treatment among college students with latent tuberculosis infection in Shandong, ChinaFlow chart of the sampling in this study. SPPHCC Shandong Provincial Public Health Clinical Center, PPD purified protein derivative, TB tuberculosis, LTBI latent tuberculosis infection. Induration diameter = (transverse diameter + longitudinal diameter)/2 (mm)Back to article page