Table 2. Six-month transition probabilities used in the United Kingdom model calibration.

Variable		Oncogenic HPV	Nononcogenic HPV	References
Lesion progression and regression
Normal to HPV	<35 years	0.023–0.077	0.008–0.026	HPV acquisition and regression; Franco et al (1999b); Moscicki et al (2001); Molano et al (2003); Schlecht et al (2003)
	>35 years	0.004–0.023	0.001–0.008
HPV to CIN 1	<35 years	0.045–0.050	0.037–0.042	Lesion progression and regression: Ho et al (1998); Melnikov et al (1998); Holowaty et al (1999); Schlecht et al (2003); Cantor et al (2004)
	>35 years	0.05	0.042
CIN 1 to CIN 2	<35 years	0.014–0.278	0.007–0.017
	>35 years	0.035–0.315	0.017–0.020
CIN 2 to CIN 3	<35 years	0.100–0.185	0.100–0.185
	>35 years	0.185–0.200	0.185–0.200
HPV clearance	<35 years	0.38	0.53
	>35 years	0.38	0.53
CIN 1 regression	<35 years	0.340–0.440	0.380–0.480
	>35 years	0.31	0.32
CIN 2/3 regression	<35 years	0.02	0.02
	>35 years	0.02	0.02
Progression to invasive cancer
CIN 3 to Cancer		0.002–0.017	0.008	Natural history of invasive cancer: De Rijke et al (2002); Goldie et al (2004)
Stage I
Progression to stage II		0.11	0.11
Probability of symptoms		0.075	0.075
Mortality		0.005–0.015	0.005–0.015
Stage II
Progression to stage III		0.12	0.12
Probability of symptoms		0.113	0.113
Mortality		0.015–0.040	0.015–0.040
Stage III
Progression to stage IV		0.12	0.12
Probability of symptoms		0.3	0.3
Mortality		0.050–0.090	0.050–0.090
Stage IV
Probability of symptoms		0.45	0.45
Mortality		0.070–0.120	0.070–0.120

Ranges are reported owing to probability variation in age and HPV type. References are provided that support the resulting transition probability values.

CIN (cervical intraepithelial neoplasia) 1 lesions can regress to HPV (human papillomavirus) infection or normal; CIN2/3 lesions can regress to HPV infection or normal. Details of the point estimates from the calibrated model are available from the authors upon request.