title: Performance and cost analysis of Siriraj liquid-based cytology: a direct-to-vial study.
abstract: OBJECTIVE
  To compare the cytological diagnoses, specimen adequacy, and cost of the Siriraj liquid-based cytology (LBC) with those of the conventional smear technique.
  
  
  METHODS
  An observational study with historical comparison was conducted in a tertiary university hospital. Cytological reports of 23,676 Siriraj-LBC specimens obtained in 2006 were compared with those of 25,510 conventional smears obtained in 2004.
  
  
  RESULTS
  Overall prevalence of abnormal cervical cytology detected by conventional smear was 1.76% and by Siriraj-LBC was 3.70%. Compared with the conventional method, the Siriraj-LBC yielded a significantly higher overall detection rate of abnormal cervical cytology, with a 110.23% increase in the detection rate (P<0.001), mainly due to the increase in diagnosis of squamous intraepithelial lesions (SIL), both low and high grade, together with atypical squamous cells of undetermined significance, "atypical squamous cells cannot exclude HSIL", and malignancies, but not atypical glandular cells. The Siriraj-LBC had a smaller proportion of unsatisfactory slides (4.94% vs. 18.60%, P<0.001) and a higher negative predictive value (96.33% vs. 92.74%, P=0.001), but no difference in positive predictive value (83.03% vs. 86.83%, P=0.285). The cost of Siriraj-LBC was approximately 67% higher than that of the conventional cytology used in Siriraj Hospital and 50-70% lower than that of the commercially available LBC techniques in Thailand.
  
  
  CONCLUSIONS
  The Siriraj-LBC increases the detection rate of abnormal cytology, improves specimen adequacy, and enhances the negative predictive value without compromising the positive predictive value. For centers where conventional Pap smear does not perform well, the introduction of a low cost Siriraj-LBC might help to improve performance and it may be an economical alternative to the commercially available liquid-based cytology.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Rd., Bangkok 10700, Thailand.
authors.forename: Somsak
authors.initials: S
authors.lastname: Laiwejpithaya
authors.forename: Mongkol
authors.initials: M
authors.lastname: Benjapibal
authors.forename: Sujera
authors.initials: S
authors.lastname: Laiwejpithaya
authors.forename: Weerasak
authors.initials: W
authors.lastname: Wongtiraporn
authors.forename: Suthi
authors.initials: S
authors.lastname: Sangkarat
authors.forename: Manee
authors.initials: M
authors.lastname: Rattanachaiyanont
mesh_terms: D000328:Adult; D003365:Costs and Cost Analysis; D005260:Female; D006801:Humans; D008875:Middle Aged; D065006:Papanicolaou Test; D011237:Predictive Value of Tests; D002583:Uterine Cervical Neoplasms / Q000175:diagnosis; D014626:Vaginal Smears / Q000191:economics* / Q000379:methods*