Adherence patterns to extended cervical screening intervals in women undergoing human papillomavirus (HPV) and cytology cotesting

Although guidelines have recommended extended interval cervical screening using concurrent human papillomavirus (HPV) and cytology ("cotesting") for over a decade, little is known about its adoption into routine care. Using longitudinal medical record data (2003-2015) from Kaiser Permanente Northern California (KPNC), which adopted triennial cotesting in 2003, we examined adherence to extended interval screening. We analyzed predictors of screening intervals among 491,588 women undergoing routine screening, categorizing interval length into early (< 2.5 years), adherent (2.5 < 3.5 years), or late (3.5 < 6.0 years). We also examined repeated early screening in a subgroup of 50,691 women. Predictors examined included: cohort year (defined by baseline cotest, 2003-2009), race/ethnicity, and baseline age. Compared to the 2003 cohort, women in the 2009 cohort were significantly less likely to screen early (aOR = 0.22, 95% CI = 0.21, 0.23) or late (aOR = 0.47, 95% CI = 0.45, 0.49). African American (AA) and Hispanic women were less adherent overall than Non-Hispanic White women, with increased early [(AA: aOR = 1.21, 95% CI = 1.17, 1.25) (Hispanic: aOR = 1.08, 95% CI = 1.06, 1.11)] and late screening [(AA: aOR = 1.23, 95% CI = 1.19, 1.27) (Hispanic: aOR = 1.06, 95% CI = 1.03, 1.08)]. Asian women were slightly more likely to screen early (aOR = 1.03, 95% CI = 1.01, 1.05), and less likely to screen late (aOR = 0.92, 95% CI = 0.90, 0.94). Women aged 60-64 years were most likely to screen early for two consecutive intervals (aOR = 2.09, 95% CI = 1.91, 2.29). Our study found that widespread and rapid adoption of extended interval cervical cancer screening is possible, at least in this managed care setting. Further research examining multilevel drivers promoting or restricting extended interval screening across diverse healthcare settings is needed.