Table 1. Characteristics of the case-control material.

	Single smear cohort		Random smear cohort
	Cases	Controls	Cases	Controls
n	62	501	139	548
Year of birth
Mean	1946.8	1949.0	1946.6	1949.0
Range	1922–1965	1922–1968	1922–1968	1922–1968
Age at smear collection
Mean	34.7	30.9	34.6	29.8
Range	20–62	15–63	15–62	15–63
Human DNA
Meana	159.8	219.2	175.7	206.2
Range	5.0–1354	5.4–6264	5.0–2465	5.0–15914
HPV 16
No of positive women	28	28	87	56
No of positive smears	28	28	120	66
Mean viral loadb	138.3	17.7	97.0	12.9
Range	0.05–2812	0.02–300.3	0.03–2812	0.01–300.3
HPV 31
No of positive women	5	19	9	34
No of positive smears	5	19	15	39
Mean viral loadb	17.7	37.4	29.8	50.5
Range	0.50–36.7	0.03–543.1	0.3–147.2	0.02–762.6
HPV 18/45
No of positive women	8	28	28	55
No of positive smears	8	28	39	64
Mean viral loadb	157.6	77.2	265.3	71.4
Range	0.11–1158	0.01–1402	0.02–5105	0.01–2044

^aMean estimated number of human cells equivalents per reaction.

^bMean number of HPV genomes per human cell equivalent.