HIV positive MSMs:
Screening with anal PAPs every two years when CD4 counts were greater than 500 resulted in a 2.7-month gain in quality-adjusted life expectancy with a cost-effectiveness ratio of  $13, 000/quality-adjusted life year saved (comparable to bactrim PCP prophylaxis cost per year saved).  Screening every year resulted in a 3-month gain in quality-adjusted life expectancy with a cost-effectiveness ratio of $16, 600/quality-adjusted life year saved.
Initiation of screening with anal PAP when the CD4 count was less than 500 was less cost effective but the cost-effectiveness was still less than $25, 000/quality-adjusted life year saved [16].

HIV negative MSMs:
Screening with anal PAP every 3 years provided for a 1.8 month gain in quality-adjusted life expectancy when compared to no screening.  This approach generated a cost effectiveness ratio of $7,000/quality-adjusted life year saved.  Screening every 2 years increased the cost effectiveness ratio to $15, 100/quality-adjusted life years saved [17]

           The cost-effectiveness of this screening protocol is thus acceptable in the studied populations when compared to that of other preventative health measures ($180,000/year of life saved for triennial cervical cancer screening in HIV-negative women) [1].  The validity of this data depends on the assumption that HSIL is truly a precursor of anal cancer, a presumed, but as of yet unproven theory.

           The cost-effectiveness data available regarding screening for ASIL is in HIV positive and negative homosexual and bisexual males.   At the time of this review, no studies focused on cost effectiveness of these screening modalities in women.  Clearly, there is a need for more research into the clinical and cost effectiveness in this neglected population.  The following information reflects the two major cost effectiveness studies available in the medical literature: