Table 3. Odds ratios (relative risks) for various levels of abnormality for the first smear after the age of 50 years by number of negative smear episodes between the ages of 40 and 49 years, after allowance for time since last smear.

Exposure group	Borderline or worse OR (95% CI)	Mild dyskaryosis or worse OR (95% CI)	Moderate dyskaryosis or worse OR (95% CI)	Severe dyskaryosis or worse OR (95% CI)
Positive	1.00	1.00	1.00	1.00
Two negative episodes	0.67 (0.59–0.77)***	0.62 (0.48–0.80)***	0.58 (0.39–0.84)**	0.49 (0.30–0.83)**
Three negative episodes	0.54 (0.47–0.62)***	0.50 (0.38–0.65)***	0.49 (0.33–0.73)***	0.39 (0.23–0.68)***
Four negative episodes	0.52 (0.42–0.66)***	0.40 (0.25–0.64)***	0.27 (0.12–0.61)***	0.13 (0.03–0.56)**

^**P<0.01, ^***P<0.001.