Table 4:

Autoimmune disorders diagnosed after quadrivalent human papillomavirus vaccination, stratified by time since vaccination

Exposure risk window, d*	No. of exposed cases	Rate ratio (95% CI)		p value§
		Unadjusted†	Adjusted‡
7–24	22	0.87 (0.49–1.11)	0.95 (0.61–1.48)	0.1 0.2
25–42	40	1.38 (0.74–1.42)	1.31 (0.93–1.84)
43–60	15	0.73 (0.44–1.42)	0.97 (0.57–1.66)

Note: CI = confidence interval, HPV = human papillomavirus, HPV4 = quadrivalent HPV.

^*The duration of time following each dose of the HPV4 vaccine during which the occurrence of an event is attributable to the effects of the vaccine.

^†Unadjusted rate ratios were derived from self-matched models that implicitly controlled for time-fixed confounders and only included the HPV vaccine (exposure).

^‡Adjusted for age at diagnosis, seasonality (Table 2), receipt of non-HPV vaccines (7–60 d before diagnosis) and recent infection (7–60 d before diagnosis), and implicitly adjusted for time-fixed confounders through the use of a self-matched analysis.

^§p value for 2-sided test of interaction between risk windows using a significance threshold of α = 0.05.