Table 2.

Evidence for Screening Women aged 21–29

PATIENTS/POPULATION	Women aged 21–29
INTERVENTION	Screening with cytology every 3 years
COMPARATOR	Screening with cytology every 1 year
OUTCOME	MAIN RESULT	NUMBER OF STUDIES	*QUALITY OF EVIDENCE	COMMENTS
CIN3+
Cancer incidence	Increase in lifetime number of cancers per 1000 women from 3/1000 to 5–8/1000	562,63,68–70	Moderate	Modeling studies—indirect evidence, but consistent across studies; results for every 2 years intermediate between every 1 and every 3 years
Colposcopies	Decrease in lifetime colposcopies per 1000 women from 760/1000 to 2000/1000	262,63	Moderate	Modeling studies—indirect evidence, but consistent across studies; results for every 2 years intermediate between every 1 and every 3 years
*GRADE Working Group grades of evidence
HIGH	We are confident that the true effect lies close to what was found in the research
MODERATE	The true effect is likely to be close to what was found, but there is a possibility that it is substantially different.
LOW	The true effect may be substantially different from what was found VERY LOW We are very uncertain about the effect.