Identification of the Medication Regimen Complexity Index as an Associated Factor of Nonadherence to Antiretroviral Treatment in HIV Positive Patients

Background: Multiple studies have identified a relationship between the complexity of a medication regimen and non-adherence. However, most studies in people who live with HIV (PLWH) have focused on antiretroviral use and have failed to consider the impact of other medications. Objective: The aim of our study is to identify the Medication Regimen Complexity Index (MRCI) as an associated factor for nonadherence to antiretroviral treatment (ART). The secondary aim is to analyze the relationship between clinical and pharmacotherapeutical variables and adherence to antiretroviral treatment and to generate an adherence model. Methods: A transversal, observational study. Patients included were PLWH over 18 years of age on active antiretroviral therapy. Patients who participated in clinical trials or who did not meet the inclusion criteria were excluded. We had studied HIV transmission mode, viral load, treatment status, number of comorbidities and complexity index as factors associated with adherence to ART. Results: We included 619 patients in the study. Number of comorbidities (p = 0.021; OR = 1.038-1.570); viral load (p = 0.023; OR = 1.108-4.505) and MRCI (p < 0.001; OR = 1.138-1.262) (ART and concomitant treatment) were the independent associated factors to ART nonadherence. The value of the Hosmer and Lemeshow test confirmed the validity of this model (P = 0.333). Conclusion: A higher MRCI was associated with non-adherence. Therefore, the regimen complexity calculation may be appropriate in daily practice for identifying patients at a higher risk of becoming non-adherent.