Risk of high-grade CIN in relation to time since first exposure to HPV 16

Time since first exposure Relative hazards ratio

(months) (95% CI)*

Unexposed 1·00

ɞ 5·98 (1·33-26·85)

6-12 18·02 (5·50-59·03)

12-18 14·22 (3·76-53·86)

ᡊ 2·60 (0·75-8·99)

HPV=human papillomavirus; CIN=cervical intraepithelial neoplasia;

*Controlling for any other HPV exposure

Woodman CBJ, et al Lancet 2001;357:1831-36