Follow-up testing after colposcopy: five-year risk of CIN 2+ after a colposcopic diagnosis of CIN 1 or less.

OBJECTIVE: Most women referred for colposcopy are not diagnosed with cervical intraepithelial neoplasia grade 2 or worse (CIN 2+) but, nonetheless, are typically asked to return much sooner than their next routine screening interval in 3 to 5 years. An important question is how many subsequent negative Pap results, or negative Pap and human papillomavirus (HPV) cotest results, are needed before returning to an extended retesting interval.
METHODS: We estimated 5-year risks of CIN 2+ for 3 follow-up management strategies after colposcopy (Pap-alone, HPV-alone, and cotesting) for 20,319 women aged 25 years and older screened from 2003 to 2010 at Kaiser Permanente Northern California who were referred for colposcopy but for whom CIN 2+ was not initially diagnosed (i.e., "women with CIN 1/negative colposcopy").
RESULTS: Screening results immediately antecedent to CIN 1/negative colposcopy influenced subsequent 5-year CIN 2+ risk: women with an antecedent HPV-positive/atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (LSIL) Pap had a lower risk (10%) than those with antecedent atypical squamous cells cannot rule out HSIL (ASC-H; 16%, p < .0001) or high-grade squamous intraepithelial lesion or worse (HSIL+; 24%, p < .0001). For women with an antecedent HPV-positive/ASC-US or LSIL, a single negative cotest approximately 1 year after colposcopy predicted lower subsequent 5-year risk of CIN 2+ (1.1%) than 2 sequential negative HPV tests (1.8%, p = .3) or 2 sequential negative Pap results (4.0%, p < .0001). For those with an antecedent ASC-H or HSIL+ Pap, 1 negative cotest 1 year after colposcopy predicted lower subsequent 5-year risk of CIN 2+ (2.2%) than 1 negative HPV test (4.4%, p = .4) or 1 negative Pap (7.0%, p = .06); insufficient data existed to calculate the risk after sequential negative cotests for women with high-grade antecedent cytology.
CONCLUSIONS: Women with a CIN 1/negative colposcopy followed by negative postcolposcopy tests did not achieve sufficiently low CIN 2+ risk to return to 5-year routine screening. For women with antecedent HPV-positive/ASC-US or LSIL, a single negative postcolposcopy cotest reduced their risk to a level consistent with a 3-year return. For women with antecedent ASC-H or HSIL+, no single negative test result sufficed to reduce their risk to a level consistent with a 3-year return.