Back to Browse Journals » Drug, Healthcare and Patient Safety » Volume 5

Polypharmacy and adverse drug reactions in Japanese elderly taking antihypertensives: a retrospective database study

Authors Sato I, Akazawa M

Published Date June 2013 Volume 2013:5 Pages 143—150

DOI http://dx.doi.org/10.2147/DHPS.S45347

Received 17 March 2013, Accepted 13 May 2013, Published 24 June 2013

Izumi Sato,1 Manabu Akazawa2

1Department of Epidemiology and Statistics, Graduate School of Medicine, The University of Tokyo Tokyo, Japan; 2Department of Public Health and Epidemiology, Meiji Pharmaceutical University, Tokyo, Japan

Background: The concomitant use of multiple medications by elderly patients with hypertension is a relatively common and growing phenomenon in Japan. This has been attributed to several factors, including treatment guidelines recommending prescription of multiple medications and a continuing increase in the elderly population with multiple comorbidities.
Objective: This study was aimed at investigating the association between polypharmacy, defined as the concomitant use of five or more medications, and risk of adverse drug reaction (ADR) in elderly Japanese hypertensive patients to examine the hypothesis that risk of ADR increases with the administration of an increasing number of co-medications.
Methods: Using a retrospective cohort design, the data regarding all hypertensive patients aged 65 years or older were extracted from the Risk/Benefit Assessment of Drugs – Analysis and Response Council antihypertensive medication database. The data were reviewed for classification of patients into one of three groups according to drug use at the initiation of therapy – a monotherapy group composed of patients who had taken the investigated drug only, a co-medication group composed of patients who had taken the investigated drug and a maximum of three other medications, and a polypharmacy group composed of patients who had taken the investigated drug and four or more other medications – and determination of the number of ADR events experienced. Estimated rate ratios (RRs) and 95% confidence intervals (CIs) were calculated using a Poisson regression model adjusted for drug category and patient age and sex. Various sensitivity analyses were performed to confirm the robustness of the study findings.
Results: Of 61,661 elderly Japanese patients (men, 41.8%; 75 years or older, 35.1%) registered in the database, 2491 patients (4.0%) experienced a total of 3144 ADR events during the study period. The rate of ADR per 10,000 person-days was 2.0 for the monotherapy group, 5.1 for the co-medication group, and 8.6 for the polypharmacy group. After adjusting for age, sex, and initial antihypertensive therapy, the RR was estimated at 2.4 (95% CI, 2.2–2.6) for the co-medication group and 4.3 (95% CI, 3.8–4.8) for the polypharmacy group, when compared with the monotherapy group.
Conclusion: The use of polypharmacy increases the risk of ADR among elderly Japanese patients with hypertension, calling for regular medication review to eliminate the administration of unnecessary co-medications.

Keywords: adverse drug reaction, antihypertensive, elderly, pharmacoepidemiology, polypharmacy

Download Article [PDF] View Full Text [HTML] 

Creative Commons License This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution - Non Commercial (unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php

Readers of this article also read:

Is routine antenatal venereal disease research laboratory test still justified? Nigerian experience

Nwosu BO, Eleje GU, Obi-Nwosu AL, Ahiarakwem IF, Akujobi CN, Egwuatu CC, Onyiuke COC

International Journal of Women's Health 2015, 7:41-46

Published Date: 7 January 2015

Glaucoma associated with the management of rhegmatogenous retinal detachment

Mangouritsas G, Mourtzoukos S, Portaliou DM, Georgopoulos VI, Dimopoulou A, Feretis E

Clinical Ophthalmology 2013, 7:727-734

Published Date: 15 April 2013

A matched-control comparison of serious adverse events after intravitreal injections of bevacizumab for age-related macular degeneration and cataract extraction

Fischer N, Moisseiev E, Waisbourd M, Goldstein M, Loewenstein A

Clinical Ophthalmology 2013, 7:621-625

Published Date: 26 March 2013

Effect of molecular weight of polyethyleneimine on loading of CpG oligodeoxynucleotides onto flake-shell silica nanoparticles for enhanced TLR9-mediated induction of interferon-α

Manoharan Y, Ji Q, Yamazaki T, Chinnathambi S, Chen S, Ganesan S, Hill JP, Ariga K, Hanagata N

International Journal of Nanomedicine 2012, 7:3625-3635

Published Date: 16 July 2012

Nonselective ß-blocker propranolol for orbital and periorbital hemangiomas in infants: a new first-line of treatment?

El-Essawy R, Galal R, Abdelbaki S

Clinical Ophthalmology 2011, 5:1639-1644

Published Date: 18 November 2011

Role of lapatinib in the first-line treatment of patients with metastatic breast cancer

Catherine Oakman, Marta Pestrin, Elena Zafarana, et al

Cancer Management and Research 2010, 2:13-25

Published Date: 7 January 2010

Risk factors associated with methamphetamine use and heart failure among Native Hawaiians and other Pacific Island peoples

Marjorie K Mau, Karynna Asao, Jimmy Efird, Erin Saito, Robert Ratner, et al

Vascular Health and Risk Management 2009, 5:45-52

Published Date: 7 December 2008

Assessment of acceptability and ease of use of atovaquone/proguanil medication in subjects undergoing malaria prophylaxis

V Nicosia, Giorgio Colombo, M Consentino, S Di Matteo, F Mika, et al

Therapeutics and Clinical Risk Management 2008, 4:1105-1110

Published Date: 1 September 2008

The influence of nano MgO and BaSO4 particle size additives on properties of PMMA bone cement

Alyssa Ricker, Peishan Liu-Snyder, Thomas J Webster

International Journal of Nanomedicine 2008, 3:125-132

Published Date: 17 March 2008