The detection of CIN2 and CIN3 during each study
period, among women aged 35–60 years at enrolment, is
shown in table 3. There was no signifi cant diff erence in
the group eff ect between study phases (p for heterogeneity
>0·15 in all comparisons). During the fi rst screening
round, the detection of CIN2 or CIN3 was signifi cantly
higher in the HPV group versus the cytology group, with
a detection ratio of 2·03 (95% CI 1·60–2·57). Conversely,
in the second round, the detection of CIN2–3 was
signifi cantly lower in the HPV group versus the cytology
group, with a ratio of 0·51 (0·28–0·93). For the total
detection of disease during the fi rst two screening
rounds, the ratio between the HPV group and the cytology
group was 1·66 (1·34–2·06). Results were similar for
detection of CIN2 and CIN3, separately. Among women
35 years and older, age (considered a continuous variable
in logistic regression) was not a modifi er of the group
eff ect on detection of CIN2 and 3 in round one, or in the
two rounds combined. However, the modifi cation of
group eff ect by age was of borderline signifi cance
(beta=–0·17; p=0·058) for the detection of CIN3 in round
two, suggesting that the gain in protection obtained by
HPV testing could increase with increasing age.