Classification bias of adherence level was minimized by training field interviewers on how to assess and calculate adherence percentages as well as cross-checking adherence estimates for confirmation by a field manager before data entry.
The <95% threshold used for classification of non-adherence may have been too stringent.
Table 2 shows the classification of patients into adherence groups for each adherence measure.
Tsai and his colleagues suggested a systematic classification of barriers to adherence to glaucoma pharmacotherapy, grouped into four major areas: medical regimen, patient factors, situational or environmental factors and provider factors (13).
With optimal classification, the desirable effects of adherence to evidence based recommendations (beneficial health outcome, less burden on staff and patients, and cost savings) will outweigh the undesirable effects (harms, more burden and greater costs).
The use of GBTM modeling allows the classification of unknown longitudinal patterns of adherence across population members and, compared to a more static adherence measure such as PDC, leads to the creation of adherence group classifications with increased homogeneity.
Adherence scores, which are computed using a validated algorithm allow classification of patients into highly adherent, moderately adherent and poorly adherent which has been shown to be significantly associated with viral load [ 46 ].
In accordance with the authors of the qualitative review we grouped the recommendations by the WHO classification of risk factors influencing adherence to long-term therapy [ 21].
