Research Paper:
Marie N. O'Connor, Paul Gallagher, Stephen Byrne, and Denis O'Mahony
Adverse drug reactions in older patients during hospitalisation: are they predictable? Age Ageing (2012)41(6):771-776first published online March 28, 2012 doi:10.1093/ageing/afs046
Reply letter to O'Connor
Graziano Onder, Assistant Professor, Mirko Petrovic, Chakravarthi Rajkumar, Tischa JM van der Cammen
Dear Editor
We read with interest the study by O'Connor and coll. showing that the GerontNET Adverse Drug Reactions (ADR) risk score does not reliably predict ADRs in a population of older adults admitted to a university hospital in Ireland and that number of inappropriate drugs as assessed by the STOPP criteria is the strongest predictor of ADR(1). Although we agree with O'Connor and coll. that the GerontNET ADR risk score might be improved by the inclusion of additional variables
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Dear Editor
We read with interest the study by O'Connor and coll. showing that the GerontNET Adverse Drug Reactions (ADR) risk score does not reliably predict ADRs in a population of older adults admitted to a university hospital in Ireland and that number of inappropriate drugs as assessed by the STOPP criteria is the strongest predictor of ADR(1). Although we agree with O'Connor and coll. that the GerontNET ADR risk score might be improved by the inclusion of additional variables assessing different domains we also believe that the following methodological issues are noteworthy.
First, the GerontNET ADR risk score was developed as a screening tool to assess the risk of developing ADRs and therefore is meant to be applied prospectively, before an ADR occurs, rather than retrospectively after ADRs has already happened (2). Obviously, the occurrence of an ADR may change the score (i.e. renal of hepatic toxicity related to an ADR or increment in number of drugs to treat an ADR may increase the score count). Therefore, assessment of the predictive ability of the score calculated at day 5 or day 10 after admission (as shown in figure 1 by O'Connor and coll.), when presumably a relevant part of the ADRs has already occurred, might not be meaningful any more. Similarly, ADRs occurring before hospital admission or causing hospital admission should be excluded from the comparison in the study by O'Connor and coll., since these ADRs occurred before the application of the GerontoNET ADR risk score.
A second issue relates to the classification of ADR. Identification and assessment of ADR in the study by O'Connor and coll. were performed by researchers involved in the development of STOPP criteria for inappropriate prescribing and the variable assessing these criteria appears to be the strongest predictor of ADRs in the study sample. However, researchers assessing study outcomes should preferably be blinded in order to avoid bias related to their classification. For example, the researchers who were responsible for collecting data in the study that led to the validation of the GerontoNET ADR risk score were not informed regarding variables that were entered into the score(2).
Third, inconsistency of data in the manuscript may raise some concerns. For example, in the text was mentioned that 243 participants were requiring assistance in one or more ADL, but the number indicated in table 2 is 116 ; similarly number of patients with at least four comorbidities is 412 in the text and 416 in table 2. The rate of patients with ADRs and heart failure shown in table 2 should be more than 3 times higher than what was presented (19/135=14% rather than 4%). These are relevant variables included in the final multivariate analysis presented in table 2 or in the GerontoNET score and therefore inadequate calculation of these variables might have led to incorrect results.
In conclusion, the GerontoNET ADR risk score was developed with the aim of identifying patients at increased risk of ADR, which can be the target of interventions aimed at reducing the risk of developing ADR (i.e. medication review). We agree with O'Connor et al. that the GerontoNet ADR risk score might be improved by the inclusion of additional variables and we welcome collaboration with researchers in the field of ADR in older people, as openness and exchange of ideas will almost certainly lead to improvement in the process of identifying those older people at risk of ADR, and ultimately to an improvement of the GerontoNET ADR risk score.
References 1. O'Connor MN, Gallagher P, Byrne S, O'Mahony D. Adverse drug reactions in older patients during hospitalisation: are they predictable? Age Ageing. 2012 Nov;41(6):771-6. 2. Onder G, Petrovic M, Tangiisuran B, Meinardi MC, Markito-Notenboom WP, Somers A, Rajkumar C, Bernabei R, van der Cammen TJ. Development and validation of a score to assess risk of adverse drug reactions among in- hospital patients 65 years or older: the GerontoNet ADR risk score. Arch Intern Med. 2010 Jul 12;170(13):1142-8.
Authors: Graziano Onder,1 Mirko Petrovic,2 Chakravarthi Rajkumar,3 Tischa JM van der Cammen,4
1 Department of Geriatrics - Policlinico A. Gemelli, Catholic University of the Sacred Heart, Rome, Italy 2 Department of Geriatrics and Gerontology, Ghent University Hospital, Ghent, Belgium 3 Department of Medicine, Brighton and Sussex Medical School, Brighton, UK 4 Section of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
Conflict of Interest:
None declared
Published in Age &Ageing, March 23, 2013