Increase in the LSIL/HSIL Ratio over Time: A Reflection of Effective Screening
GM Oprea-Ilies, BS Kendall, S Cameron, G Birdsong, EB Stelow, SE Pambuccian. Grady Memorial Hospital, Emory University, Atlanta, GA; Wilford Hall Medical Center, Lackland AFB, TX; Hennepin County Medical Center, Minneapolis, MN; University of Virginia, Charlottesville, VA; University of Minnesota, Minneapolis, MN
Background: We have recently proposed a new indicator, the LSIL/HSIL ratio to compare laboratories and populations screened. The aim of this study was to examine this indicator's evolution over time in five institutions with different practice settings, different patient populations and different Pap test (PT) preparations.
Design: We collected the 2001-2007 Pap test data from five institutions using different liquid-based Pap tests (3 Surepath and 2 Thinprep) and calculated the LSIL/HSIL ratio for each year for each institution, as well as the totals for all institutions. We compared the LSIL/HSIL ratio between each successive years and the %LSIL and %HSIL of the total for all institutions for the years 2001-2003 vs. 2004-2007 using the chi-square test.
Results: A total of 1,562,520 were screened at the five institutions during this seven year interval. A total of 62317 cases were diagnosed as LSIL (3.99%) and 9693 (0.62%) as HSIL, with a combined LSIL/HSIL ratio of 6.43. There was a steady increase in LSIL/HSIL ratios for all institutions.
|Inst 1 LSIL/HSIL ratio||4.31||9.68||9.93||15.13||15.86||17.95||21.09|
|Inst 2 LSIL/HSIL ratio||3.22||3.5||3.34||4.68||6.15||6.29||6.93|
|Inst 3 LSIL/HSIL ratio||2.1||2.59||3.14||3.2||2.89||3.6||3.45|
|Inst 4 LSIL/HSIL ratio||3.03||4||4.61||4.11||5.32||6.54||6.22|
|Inst 5 LSIL/HSIL ratio||4.5||4.67||4.74||6.58||7||7.17||10.15|
|Total LSIL/HSIL ratio||3.59||4.68||5.24||6.53||6.98||9.59||10.57|
The increase was statistically significant (p<0.05) for all year-to-year comparisons except for 2004-2005 and was caused both by an increase in LSIL (from 3.49% to 4.34%) and a decrease of HSIL (from 0.79% to 0.51%) from the 2001-2003 to 2004-2007 periods (both p<0.0001).
Conclusions: The steady increase in LSIL/HSIL ratios in our institutions most likely reflects a greater efficacy of cytologic screening, resulting in identification of more LSIL and prevention of the progression to HSIL.
Tuesday, March 10, 2009 2:15 PM
Platform Session: Section F, Tuesday Afternoon