Risk-Based Cervical Consensus Guidelines: Methods to Determine Management if Less Than 5 Years of Data Are Available

Abstract

Objectives: In the 2019 ASCCP Risk-Based Management Consensus Guidelines, clinical management decisions are based on immediate and 5-year cervical intraepithelial neoplasia (CIN) 3+ risk estimates. However, data for technologies other than human papillomavirus testing and cytology may be limited to clinical trials and observational studies of shorter duration than 5 years. To enable decisions about 1- or 3-year intervals, 3-year CIN 3+ risk equivalents to 5-year CIN 3+ risk thresholds were generated.

Materials and methods: We examined screening test result scenarios around the 5-year risk thresholds of 0.15% and 0.55% and calculated the average percent increase in CIN 3+ risk from 3 to 5 years. Using this average increase, we obtained estimates of corresponding risk thresholds at 3 years. We then validated whether use of the 3-year risk threshold would have resulted in equivalent management per the 2019 recommendations.

Results: Around the 5-year CIN 3+ risk threshold of 0.55%, the average increase in risk from 3 to 5 years was 0.16%. Therefore, the equivalent threshold for 3-year risk was estimated as 0.39%. We found no difference in recommendations to return in 1 or 3 years using the 3-year or 5-year risk thresholds in 66 of the 67 scenarios (98.5%) in follow-up in 2019 guidelines.

Conclusions: In this methodological addendum, the Enduring Guidelines Committee adopted the use of the 0.39% 3-year CIN 3+ risk threshold as equivalent of the 0.55% 5-year CIN 3+ risk threshold for technologies with fewer than 5 years of follow-up data. This allows evidence-based guidance for surveillance intervals of 1 or 3 years for new technologies with limited longitudinal data.

FIGURE 1

Increase in CIN 3+ risk from year 3 to year 5 among test results with 5-year CIN 3+ risk around 0.15%. Cumulative risk curve for scenarios with 5-year CIN 3+ risk around 0.15% with each color corresponding to a different scenario from Table 1. For these scenarios, we obtained the weighted average increase from years 3 to 5, weighted by frequency of occurrence as indicated by N in Table 1. The average percentage increase from 3- to 5-year CIN 3+ risk is calculated as 0.06%. The red line in the figure represents 0.06% increase from 3- to 5-year risk, and hence, the equivalent clinical action management threshold for a 3-year follow-up is obtained as 0.09% CIN 3+ 3-year risk, which is equivalent to 0.15% CIN 3+ 5-year risk. Only scenarios with large numbers (10 or more) of observed CIN 3+ cases are plotted.

FIGURE 2

Increase in CIN 3+ risk from 3-year to 5-year among the test results which have 5-year CIN 3+ risk around 0.55%. Cumulative risk curve for scenarios with 5-year CIN 3+ risk around 0.55% with each color corresponding to a different scenario from Table 2. For these scenarios, we obtained the weighted average increase from years 3 to 5, weighted by frequency of occurrence as indicated by N in Table 2. The red line in the above figure is the estimated trend line showing the 0.16% increase from 3- to 5-year CIN 3+ risk, so the equivalent clinical action threshold for a 1-year follow-up is determined as 0.39% CIN 3+ 3-year risk (which is equivalent to 0.55% CIN 3+ 5-year risk threshold). Only scenarios with large numbers (10 or more) of observed CIN 3+ cases are plotted.

FIGURE 3

Updated risk-based management algorithm. The figure presented in the 2019 ASCCP Risk-Based Management Consensus Guidelines is updated according to this approved method presented in this report. If 5-year risk is not available for any screening test, the algorithm extends below, first checking whether 3-year CIN 3+ risk is available. If it is, the length of follow-up interval is determined by the new threshold at 3-year risk (0.39%). The recommendation is either 1- or 3-year return according to the 3-year risk of the patient. If 3-year risk is not also available, then the recommended management is to return in 1 year.