cantly delay the progression of AIDS and associated disease complications among HIV-infected women (Fawzi et al., 2004). Clearly, then, food and nutrition assistance programs should be a resource available to those using ART.

THE IMPORTANCE OF ADHERENCE

As noted, ART for HIV/AIDS involves taking a complex regimen of drugs with, at times, unforgiving requirements, such as dosage timing and coadministration with food. Following this regimen scrupulously is central to durable and effective HIV therapeutic responses. A first step in successful adherence, however, is agreement on all the dimensions that this term should encompass. Numerous possible interpretations of adherence fall short of the recognition that to be adherent, patients must access properly stored ARVs and then take all prescribed drugs at the prescribed frequency and intervals and when called for with alimentation. Wider-than-recommended intervals can lead to intermittently suboptimal drug concentrations and a heightened risk of resistance emergence (see Chapter 3). The complexity of the task of assessing adherence defies the use of a single simple measurement. Indicative of the challenge is that investigators have pursued multiple approaches to ascertain different aspects of compliance, including the following:

  • Percentage of doses taken—total doses taken/number of prescribed doses

  • Proportion of days correct doses taken—number of days correct doses were taken/number of days of follow-up

  • Mean doses per day—number of doses taken/number of days cap was opened

  • Mean interdose interval—sum of all intervals between doses/number of doses taken

  • Drug holidays—count of intervals that were more than 3 days

  • Proportion of days with no doses taken—number of days with no recorded dose/number of days of follow-up

  • Dose difference—mean difference between the time each dose was taken and the “correct time” as projected from the first dose

  • Proportion of doses in dosing periods—two periods defined around the prescribed interval (either 4-hour or ±25 percent interval length)

The problem of poor adherence, however measured, to prescribed, self-administered medications generally is well documented, particularly for chronic and asymptomatic conditions (WHO, 2003e). As noted, however, one concern associated with poor adherence that is specific to ART is the



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