Scotland introduced hr-HPV testing to the follow-up of women treated at colposcopy for CIN in April 2012. Women who test hr-HPV negative and cytology negative or borderline/ASCUS are deemed ‘cured’ and return to routine recall in 3 years. Women who test positive for hr-HPV and/or cytology (⩾LG dyskaryosis) are referred for colposcopy. Women with a negative colposcopy examination remain under annual cytology surveillance for 2 (CIN1) or 5 years (CIN2/3). Routine cytology has now been received from many women returned to routine recall.
Data on hr-HPV and cytology test dates and results, date and outcome of follow-up colposcopy and follow-up cytology tests were obtained from the national screening database. The sensitivity, specificity, PPV and NPV of cytology alone, hr-HPV testing alone and both (as a cotest) for recurrent/residual CIN at 6 months has been calculated. The prevalence of abnormal cytology in women managed by TOC was compared to the routine screening population.
By 30 November 2015, 14,156 women had undergone TOC, of whom 10,579 were returned to routine recall and 3577 were referred for colposcopy. 1,339 women given routine recall have had more than 37 months of follow-up, of whom 801 have had subsequent cytology. Only 1 case (0.12%) of HG cytology was found in this population. 852 of the 9240 women (9.22%) returned to routine recall with less than 37 months follow-up have been rescreened before their due date.
213 women (5.95% of referrals) were referred for follow-up colposcopy with positive cytology only, 2.553 (71.77%) with a positive hr-HPV test only and 811(22.67%) women had both tests positive. Sensitivity, specificity, PPV and NPV for detection of recurrent/residual CIN2+ at 6 months following treatment are shown in the table. 45 out of 223 cases of CIN2+ were positive with only one test (9 cytology only, 36 hr-HPV only). 3157 of women referred (88.26%) had negative follow-up colposcopy, of whom 1958 have returned for cytological follow-up. 66 additional cases of HG dyskaryosis have been identified and 205 cases of LG dyskaryosis in their period of follow-up of up to 36 months.
|
Cytology performance |
Co-test performance |
hr-HPV performance |
|
|---|---|---|---|
| Sensitivity |
83.86% |
79.82% |
95.96% |
| Specificity |
75.19% |
81.48% |
6.05% |
| PPV |
18.42% |
22.14% |
6.39% |
| NPV |
98.59% |
98.34% |
95.73% |
Our results support the use of both cytology and hr-HPV testing in the follow-up of treated CIN. The selective use of either test will miss some cases of CIN2+ at six months, and cytological follow-up of negative colposcopies is important. Routine recall of women ‘cured’ is safe.