ART as a strategy for “treatment-as-prevention” is frequently acknowledged.  Public health efforts, in the US as elsewhere, have focussed on prompt initiation of ART for the newly-diagnosed so as to shorten the duration of viremia – and thereby also reduce transmission risk.  But what about the public health implications of people living with HIV (PLWH) who have been diagnosed, but are disengaged, or poorly engaged with ART?

Contributions to STIs journal from the UK have discussed disengagement from a clinical perspective, its various social and behavioural concomitants (http://sti.bmj.com/content/early/2013/05/21/sextrans-2012-050966.abstract?sid=a9129e3e-e0b9-4e00-ad11-7023dd74276f; http://sti.bmj.com/content/79/4/349.3.full?sid=a9129e3e-e0b9-4e00-ad11-7023dd74276f).  However, in the US (and no doubt other countries) where the proportion of PLWH with consistently suppressed viral load (VL) is estimated at just 28%, with a large proportion of PLWH lost to follow-up (an estimated 35% in New York City), the public health impact of disengagement also becomes a serious concern.  For a start, the impact of early ART initiation as a “treatment-as-prevention” strategy can only be very limited.

A recent longitudinal study of a New York City (NYC) Health Department intervention to re-engage “persons lost to follow-up” (LTFU), sets out to consider the public health case for deploying resources on the “disengaged”, as well as the “not yet initiated” (http://journals.lww.com/aidsonline/pages/results.aspx?txtKeywords=Udeagu).  Existence of mandatory named HIV and laboratory reporting in NYC makes such an intervention a theoretical possibility. But how useful would surveillance data prove in locating LTFU – and how willing would the LTFU themselves be to re-engage with care?  These were the issues confronting the public health case workers conducting the investigation over the period 2008-2010.

Of the 797 PLWH presumed LTFU 409 (60%) were confirmed LTFU after elimination of those who could not be located, and those who turned out current-to-care after all.  Of these 409, 240 (59%) are classified as having returned to care as a result of the intervention  on the basis of HIV visit confirmed through medical record review or CD4/VL test report; however, most (97%) of the 240 also had at least one CD4 or VL test performed during the 12-months subsequent to their first return-to-care visit.  The returned-to-care group were much more likely to have had CD4/VL reported that those who refused linkage-to-care (95% vs 39%).  More disappointingly – only 65 partners were named in the course of the exercise, and ultimately only 3 newly diagnosed with HIV infection as a direct result of the study intervention.

The most important finding is the willingness of LTFU clients to re-engage with care, and the extent of their successful retention in care after re-engagement.  Other findings relate to the serviceability of the laboratory, surveillance and jurisdictional infrastructure for the purposes of the provision of a more comprehensively “wrap-around” care programs capable of improving retention in care.  Here the issues identified are the timely availability of laboratory information, the potential of linkage between surveillance data and the hospital record system, both of which could have saved expenditure on the location of presumed LTFU who turned out to be “current-to-care”. (The Louisiana Information Public Health Exchange is held up as a potential model of what can be achieved: http://www.lsms.org/site/images/stories/LaPhie-Non-techincal%20Guide.pdf).