Prevalence and Predictors of Potential Drug-Drug Interactions in the Elderly: A Cross-Sectional Study in the Brazilian Primary Public Health System

Abstract

Purpose. The primary objective of this study was to investigate the prevalence of clinically important potential drug-drug interactions (DDIs) in elderly patients attending the public primary health care system in Brazil. The secondary objective was to investigate possible predictors of potential DDIs. Methods. A cross-sectional study was carried out in 5 Brazilian cities located in the Ourinhos Micro-region, Sao Paulo State, between November 2010 and April 2011. The selected sample was divided according to the presence (exposed) or absence (unexposed) of one or more potential DDIs (defined as the presence of a minimum 5-day overlap in supply of an interacting drug pair). Data were collected from medical prescriptions and patients’ medical records. Potential DDIs (rated major or moderate) were identified using 4 DDI-checker programs. Logistic regression analysis was used to study potential DDI predictors. Results. The prevalence of clinically important potential DDIs found during the study period was 47.4%. Female sex (OR = 2.49 [95% CI 2.29–2.75]), diagnosis of ≥ 3 diseases (OR = 6.43 [95% CI 3.25–12.44]), and diagnosis of hypertension (OR = 1.68 [95% CI 1.23–2.41]) were associated with potential DDIs. The adjusted OR increased from 0.90 [95% CI 0.82–1.03] in patients aged 60 – 64 years to 4.03 [95% CI 3.79 – 4.28] in those aged 75 years or older. Drug therapy regimens involving ≥ 2 prescribers (OR = 1.39 [95% CI 1.17–1.67]), ≥ 3 drugs (OR = 3.21 [95% CI 2.78–3.59]), ≥ 2 ATC codes (OR = 1.19 [95% CI 1.12–1.29]), ≥ 2 drugs acting on cytochrome P450 (OR = 2.24 [95% CI 2.07–2.46]), and ATC codes B (OR = 1.89 [95% CI 1.05–2.08]) and C (OR = 4.01 [95% CI 3.55–4.57]) were associated with potential DDIs. Conclusion. Special care should be taken with the prescription and therapeutic follow-up of patients who present characteristics identified as predictors. Knowledge of potential DDI predictors could aid in developing preventive practices and policies that allow public health services to better manage this situation.
 
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Pharmacoepidemiological profile and polypharmacy indicators in elderly outpatients

“…Similar to previous Brazilian studies, our sample presented a high prevalence of chronic diseases, with hypertension, diabetes and dyslipidemia being the most common ones (Rozenfeld, Fonseca, Acurcio, 2008, Obreli-Neto et al, 2011, Obreli-Neto et al, 2012b. The high prevalence of chronic diseases is onerous for the health system, a fact also encountered in other studies with elderly patients (Leite-Cavalcanti et al, 2009;Crentsil et al, 2010), and should serve as an alert for health service planning due to the process of population ageing, since chronic diseases require continuous treatment and monitoring (Abegunde, Stanciole, 2006).…”

Drug-drug interactions and adverse drug reactions in polypharmacy among older adults: an integrative review

“…Of the 47 records resulting from the search strategies, 24 (51.1%) full-text articles were retrieved for review concerning ADR 11 - 18 , 20 , 24 - 25 , 28 - 29 , 34 - 36 , 38 - 40 , 46 , 51 - 52 , 54 , 56 ) , 14 (29.8%) DDI 21 - 23 , 27 , 30 - 33 , 41 , 43 - 45 , 49 , 53 and nine (19.1%) are related to both DDI and ADR 19 , 26 , 37 , 42 , 47 - 48 , 50 , 55 , 57 , according to Figures 2 and 3.…”

Potential drug–drug interactions among elderly patients admitted to medical ward of Ayder Referral Hospital, Northern Ethiopia: a cross sectional study

“…A number of other studies have also identified an increase number of medications a predictor of DDI in the elderly [6, 9, 15, 30, 34–41]. A study from Brazil reported that the potential drug interaction risk when patients are taking 2–3, 4–5 and 6–7 medications was 39, 88.8 and 100 %, respectively [36].…”

“…Though the incidence of actual DDIs is lower than that of potential DDIs, some studies have found as high as 25–47 % clinically relevance potential DDIs in the elderly [33, 41]. The occurrence of clinically important interactions depends in the presence of specific risk factors such as polypharmacy, comorbidity, age, therapeutic range and dosage of the drug [42].…”