Age‐specific patterns of unsatisfactory results for conventional Pap smears and liquid‐based cytology: data from two randomised clinical trials

Please cite this paper as: Castle P, Bulten J, Confortini M, Klinkhamer P, Pellegrini A, Siebers A, Ronco G, Arbyn M. Age‐specific patterns of unsatisfactory results for conventional Pap smears and liquid‐based cytology: data from two randomised clinical trials. BJOG 2010;117:1067–1073. Objective To investigate the rate of unsatisfactory cervical cell samples in liquid‐based cytology (LBC) versus conventional cytology (CC) by age. Design Randomised clinical trials. Setting Population‐based cervical cancer screening in the Netherlands and Italy. Population Asymptomatic women invited for screening enrolled in two randomised trials: Netherlands ThinPrep® versus conventional cytology (NETHCON; 39 010 CC, 46 064 LBC) and New Technologies in Cervical Cancer Screening (NTCC; 22 771 CC, 22 403 LBC). Methods Comparison of categorical variables using Pearson’s chi‐square test, logistic regression and trend tests. Main outcome measures Proportion of unsatisfactory samples, ratio of LBC versus CC, and variation by 5‐year group. Results In NETHCON, a lower percentage of LBC samples were judged to be unsatisfactory compared with CC samples (0.33 versus 1.11%). There was no significant trend in unsatisfactory results by age group for conventional cytology (Ptrend = 0.54), but there was a trend towards an increasing percentage of unsatisfactory results with increasing age for LBC (Ptrend