The HIV care cascade: models, measures and moving forward.
BACKGROUND
This article seeks to identify where delays occur along the adult HIV care cascade ("the cascade"), to improve understanding of what constitutes "delay" at each stage of the cascade and how this can be measured across a range of settings and to inform service delivery efforts. Current metrics are reviewed, measures informed by global guidelines are suggested and areas for further clarification are underscored.


CONCLUSIONS
Questions remain on how best to evaluate late entry into each stage of the cascade. The delayed uptake of HIV testing may be more consistently measured once rapid CD4 testing is administered at the time of HIV testing. For late enrollment, preliminary research has begun to determine how different time intervals for linking to HIV care affect individual health. Regarding treatment, since 2013, the World Health Organization (WHO) and UNAIDS recommend treatment initiation when CD4 <500 cells/mm(3); these guidelines provide a useful albeit evolving threshold to define late treatment initiation. Finally, WHO guidelines for high-, low- and middle-income countries also could be used to standardize measures for achieving viral suppression.


CONCLUSIONS
There is no "one size fits all" model as the provision of services may differ based on a range of factors. Nonetheless, measures informed by global guidelines are needed to more consistently evaluate the scope of and factors associated with delays to each stage of the cascade. Doing so will help identify how practitioners can best deliver services and facilitate access to and continued engagement in care.
RAND Corporation, Santa Monica, CA, USA; sarahm@rand.org.
Sarah
S
MacCarthy
Division of Infectious Diseases, The Miriam Hospital, Alpert Medical School of Brown University, Providence, RI, USA.
Michael
M
Hoffmann
Program on Global Health and Human Rights, Institute for Global Health, University of Southern California, Los Angeles, CA, USA.
Laura
L
Ferguson
Division of Infectious Diseases, The Miriam Hospital, Alpert Medical School of Brown University, Providence, RI, USA.
Amy
A
Nunn
Division of Infectious Diseases, Johns Hopkins University, Baltimore, MD, USA.
Risha
R
Irvin
Center for Global Health, Massachusetts General Hospital, Boston, MA, USA.|Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, Harvard Medical School, Cambridge, MA, USA.
David
D
Bangsberg
Program on Global Health and Human Rights, Institute for Global Health, University of Southern California, Los Angeles, CA, USA.
Sofia
S
Gruskin
Institute of Collective Health, Federal University of Bahia, Salvador, Brazil.
Ines
I
Dourado
D000328:Adult; D015658:HIV Infections / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D017410:Practice Guidelines as Topic
HIV/AIDS; care cascade; continuum of care; linkage to care; measures; testing; treatment cascade; viral suppression