This study was undertaken to examine routine cervical cancer screening diagnoses and outcomes on an age-specific basis in a US population.
We conducted an observational cohort study using 1997-2002 health plan administrative and laboratory data for women enrolled at Kaiser Permanente Northwest (Portland, Ore) in 1998.
Across all female enrollees (n=150,052), the annual rate of routine cervical cancer screening was 294.7 per 1,000, with cytologic abnormalities detected at a rate of 14.9 per 1,000. The annual incidence of cervical intraepithelial neoplasia (CIN) 1 was 1.2 per 1,000 with a rate of 1.5 per 1,000 for CIN 2/3. CIN 1 incidence peaked among women aged 20 to 24 years (5.1 per 1,000), with CIN 2/3 rates highest among those 25 to 29 years (8.1 per 1,000). From among 44,493 routine cervical smears, results were normal for 94.5%, with abnormal diagnoses of atypical squamous cells (3.3%), atypical glandular cells (0.2%), low-grade squamous intraepithelial lesion (1.2%), high-grade squamous intraepithelial lesion (0.3%), and inconclusive/inadequate (0.5%). Of women with abnormal routine smears, CIN or cancer was detected on follow-up in 19.4% of cases, 51.5% were found to have had a false-positive smear, and 29.0% incomplete follow-up as defined by published management guidelines.
These are the first comprehensive age-specific estimates of routine cervical cancer screening diagnoses and outcomes to be reported within a US general healthcare setting. Overall, 5% of routinely screened women were found to have an abnormal cervical smear with an annual incidence of CIN across all female enrollees of 2.7 per 1000.
Department of Population Health Sciences, University of Wisconsin-Madison, USA. email@example.com