Investigating the prevalence and management of potential drug-­drug interactions among HIV patients on treatment for comorbid illnesses: a mixed methods approach

Abstract

The high burden of comorbid conditions and diseases in HIV-­infected patients increases the risk for drug-­related problems such as drug-­drug interactions (DDIs). These DDIs can result in worsening of symptoms and/or mortality. This study aimed to determine the prevalence of potential DDIs (pDDIs) among HIV patients that are on treatment for both HIV and other comorbidities. DDI management strategies were also investigated as a way to evaluate reasons for high DDI prevalence and suggestions for future improvement. The study was conducted at the Themba Lethu HIV Clinic (TLC) in Johannesburg. A mixed methods research design was employed to achieve the objectives of this study. Within the quantitative phase, 645 electronic patient files were analysed over a 3-­year period. pDDIs were identified and categorised through Lexicomp®. A total of 5,584 pDDIs were found. Different DDI categories were identified, ranging from category A which corresponds to no evidence of a DDI, category B, minor interaction with limited clinical concern, category C, moderate interaction, category D, major interaction and category X, contraindicated interactions. Category A and B in general are of academic, but not of clinical concern whereas C, D, or X require attention. The most common pDDI rating found was Category C, 63.94%. The second highest pDDI category identified was Category D, 25.58%. The lowest prevalence of pDDIs was recorded for category X, 0.23%. The odds for pDDI exposure were associated with a higher number of comorbidities and the prevalence of pDDIs increased significantly among patients over the age of 50.The qualitative phase included three focus groups wherein the perceptions of pharmacists and pharmacy personnel on DDI management strategies were determined. The group members were made up of 9 pharmacists;; 1 intern;; 3 post basic pharmacist assistants;; 2 basic pharmacist assistants and 1 learner basic pharmacist assistant. The material used during the focus group addressed DDIs and its management. Demographic questionnaires were handed out to the participants at the beginning of each session. The focus group recordings were subjected to an inductive and essentialist thematic analysis wherein theidentification, analysis and reporting of themes or patterns occurred. Three themes emerged from the analysis;; Potential risk factors that contribute towards DDIs, Perceived barriers in the detection and management of DDIs and Recommendations/ Strategies to manage DDIs. All of the participants were aware of the prevalence of DDIs among prescriptions, 56.25% mentioned they encounter DDIs at least once a week and 81.25% had no training in the management of DDIs. Results have indicated that pharmacy personnel would like to provide pharmaceutical care such as the detection and management of pDDIs but have difficulty finding time for it. Factors such as high patient ratios, prescribing errors, polypharmacy, poor communication with patients and clinic hopping were perceived as contributing factors to drug interactions. Some of the barriers that prevent the identification and management of pDDIs reported were the attitude of pharmacy personnel, pharmacist-­prescriber relationships, resource-­related constraints and lack of knowledge. Such barriers result in negative therapeutic outcomes. To overcome these barriers, it was recommended that pharmacy personnel attend training programmes to help identify and manage DDIs. Patient education was also highlighted as a significant factor in reducing the risk of certain DDIs and increasing patient adherence. In addition, participants expressed that the use of an electronic patient database that alerts pDDIs will to a large extent reduce possible medical complications and consequences. Lastly, the use of multidisciplinary teams for HIV patients was recommended.Improvement in drug safety is essential in terms of patient morbidity/mortality and in economic terms. Most DDIs are avoidable and can be identified by applying principles of clinical pharmacology and good clinical practice. Although, moderate DDIs featured the highest which suggests that the DDIs were not severe, being able to identify these is critical for patient care. Drug-­drug Interactions are directly linked to adverse drug reactions (ADRs), both of which lead to hospital admissions. These findings fortify the need for increased vigilance of drug therapy by healthcare professionals in the prevention of drug related problems.