Background The life expectancy of HIV-infected individuals has increased, and there are many patients with other comorbidities and comedication, which could affect antiretroviral therapy (ART) adherence.

Purpose To investigate the effect of polypharmacy on ART adherence in patients with HIV infection, as well as to identify predictors of ART adherence.

Materials and methods A single-centre, retrospective study was conducted on HIV-infected patients who had started treatment before January 2012. The follow-up period was 12 months. The dependent variable was ART adherence and the independent variables were; sex, age, CD4, transmission risk, CDC classification, ART-naive, HIV viral load, number of hospital admissions, type of ART, comedication (≥5 prescription drugs) and risk of drug-related problems (DRP). Adherence was determined through pharmacy electronic dispensing records and the Morisky scale. Patients were considered adherent when they took ≥90% of prescribed ART in the last 12 months. The risk of DRP (categorised as high or low) was determined by a predictive tool developed by Morillo et al.¹ To determine the independent variables associated with adherence, we performed a univariate logistic regression and subsequently a multivariate analysis.

Results We included 594 patients in the study (80% men, median age 47 years) of whom 75% were adherent. In the univariate analysis the variables that showed statistically significant relationships with ART adherence were: intravenous drug users (IDU), AIDS-defining condition, ART-naïve, detectable viral load, ≥1 hospital admission, PI-based regimens, high-risk DRP and polypharmacy. In the multivariate analysis, IDU (OR = 0.58; CI[0.34–0.99]; p = 0.048); ART-naïve (OR = 9.94; CI[3.69–26.79]; p < 0.001); high-risk DRP (OR = 0.41; CI[0.24–0.69]; p = 0.001) and polypharmacy (OR = 0.39; CI[0.22–0.68]; p = 0.001) were independent predictors of non-adherence to ART.

Conclusions Although ART adherence is high, polypharmacy significantly reduces adherence. Similar findings have been reported by other studies.^2,3 This fact justifies the key role that the pharmacist can play in adherence monitoring. Furthermore, non-treatment-naive patients, IDU and high-risk DRP are also associated with lower adherence.

References

1. http://estudiopredictor.sefh.es/index.html (28)

2. Ekwunife OI, Oreh C, Ubaka CM. Concurrent use of complementary and alternative medicine with antiretroviral therapy reduces adherence to HIV medications. Int J Pharm Pract 2012;20(5):340-3

3. Nachega JB, Trotta MP, Nelson M, Ammassari A. Impact of metabolic complications on antiretroviral treatment adherence: clinical and public health implications. Curr HIV/AIDS Rep 2009;6(3):121-9

No conflict of interest.