Table 2.
Effects of modelling different assumptions about cervical cancer and screening when women are withdrawn from screening from age 50, are screened every three years, and 85% of eligible women are screened
| Model | Annual resources used/100 000 women (% decrease from policy of no early withdrawal)
|
Incidence of invasive cancer/100 000 women (% increase over policy of no early withdrawal) | ||
|---|---|---|---|---|
| Smear test | Colposcopy* | Test for HPV | ||
| Baseline assumptions: | ||||
| No early withdrawal | 17 600 | 218 | 0 | 10.8 |
| Policy 1 | 13 400 (23.8) | 180 (17.6) | 0 | 13.1 (21.1) |
| Policy 2 | 13 100 (25.3) | 180 (17.5) | 1160 | 12.5 (16.0) |
| Progression of disease reduced by 20%: | ||||
| No early withdrawal | 17 600 | 197 | 0 | 6.6 |
| Policy 1 | 13 400 (24.0) | 161 (18.4) | 0 | 8.0 (21.1) |
| Policy 2 | 13 100 (25.4) | 161 (18.5) | 1160 | 7.7 (15.7) |
| Progression of disease increased by 20%: | ||||
| No early withdrawal | 17 600 | 239 | 0 | 15.8 |
| Policy 1 | 13 400 (23.8) | 199 (16.8) | 0 | 19.1 (21.1) |
| Policy 2 | 13 200 (25.3) | 199 (16.6) | 1160 | 18.4 (16.5) |
| Prevalence of HPV infection beyond age 50†: | ||||
| No early withdrawal | 17 500 | 184 | 0 | 7.1 |
| Policy 1 | 13 300 (24.0) | 149 (18.9) | 0 | 8.6 (20.8) |
| Policy 2 | 13 100 (25.5) | 148 (19.5) | 1140 | 8.4 (17.8) |
| Cytology sensitivity 30% lower: | ||||
| No early withdrawal | 17 600 | 208 | 0 | 14.2 |
| Policy 1 | 13 400 (23.8) | 169 (18.8) | 0 | 16.7 (17.6) |
| Policy 2 | 13 100 (25.3) | 171 (17.8) | 1160 | 15.9 (12.0) |
| 30% more false positives as a proportion of women without precancerous lesions: | ||||
| No early withdrawal | 17 900 | 275 | 0 | 10.8 |
| Policy 1 | 13 700 (23.4) | 224 (18.5) | 0 | 13.0 (20.4) |
| Policy 2 | 13 300 (25.3) | 223 (19.1) | 1160 | 12.5 (15.7) |
HPV=human papillomavirus; in Policy 1 a woman is withdrawn from screening if she is over a specified age, her smear test result is negative, and her previous three smears were negative and taken regularly three years apart; in Policy 2 a woman is withdrawn if she is over a specified age, her smear test result is negative, and a test for HPV infection is negative for high risk types of the virus.
*
Rounded to nearest integer.
†
Prevalence = ½ × baseline assumption.