Impact of technology on cytology outcome in cervical cancer screening of young and older women.

Little is known about age-dependent variation in outcomes of cervical cytology with modern technologies. This population-based study evaluated age-dependent changes after routine implementation of ThinPrep and SurePath technology in two independent laboratories, and controlled for time trends in a third laboratory using manually read conventional cytology continually. Data were collected from the Danish National Health Care Registers. For each laboratory, we compared proportions of abnormal cytology defined as atypical squamous cells of undetermined significance or worse (ASCUS+) by age and technology phase. The study included 489,960 cytological samples with no recent abnormality from women aged 23-59 years, routinely screened between 1998 and 2007. Implementation of SurePath liquid-based cytology (LBC) was followed by an increase in abnormal cytology in women aged 23-29 years from 4.6 to 6.1%, relative proportion (RP): 1.31 [95% confidence interval (CI): 1.08-1.61], and a decrease in women aged 45-59 years from 2.9 to 2.0%, RP: 0.71 (95% CI: 0.60-0.83). Implementation of ThinPrep LBC was followed by a decrease in abnormal cytology both in women aged 23-29 years from 7.7 to 6.8%, RP: 0.89 (95% CI: 0.78-1.02) and in women aged 45-59 years from 3.4 to 1.0%, RP: 0.30 (95% CI: 0.24-0.37). With implementation of imaging-assisted reading, regardless of the brand of technology, the proportion of abnormality increased by around 30% in all age groups (range from 19 to 41%). In the laboratory with unchanged technology no trends in abnormality proportions were observed. The impact of LBC implementation on cytological abnormality proportions varied considerably across age groups.