Prediction of ADRs and Estimation of Polypharmacy in Older Patient’s Population: Retrospective Study in Russian Gerontology Center

Abstract

Background: Adverse drug reactions (ADRs) are common in the elderly and often have serious clinical and economic consequences. There have been limited studies in detecting adverse effects in patients admitting hospitals. Objective: Prediction of ADR in patients ≥ 65 years old, based on GerontoNet risk score with emphasis on polypharmacy. Methods: we studied records of 201 inpatients obtained from Medical Records Section, admitted to the Russian Gerontology Clinical Research Center (RGCRC). The GerontoNet ADR risk score was calculated for all patients. Receiver operator characteristic (ROC) curves were constructed to test the ability of the GerontoNet risk score to predict ADRs. We identified people who were 65 years old and more and placed them into one of three age groups (65–74, 75–84 and ≥ 85 year). We compared polypharmacy before admission with that during hospitalization. Results: A total of 201 patients was included in this study. The mean±SD age was 76.1±6.2 years, 74.6% were female and the median number of drugs was 8 (range 6–11). Before admission, previous exposure to ADR was observed in 46 patients (22.9%) and GerontoNet risk score (Mean± SE) was 2.54±1.4, 111 (55.2%) of patients were with 0-2 points and 90 (44.8%) patients were with ≥3 points. During hospital stay, the mean (95% CL) GerontoNet ADR risk score was 4.79 (4.51-5.08) points, range (0-9). It was higher in patients had polypharmacy, compared with those patients hadn’t polypharmacy (66.2% and 24.9% respectively).The area under the curve (ROC) was 0.887 (95% CL 0.84-0.94), the cut-off point of 4 points yielded very good sensitivity and good specificity results in these subpopulations. Before admission, polypharmacy was 36.3% in patients whereas during hospital stay was 91%. polypharmacy exposure increased during hospitalization (P ˂ 0.001), consequently GerontoNet risk scale increased. Variables participating in ADR risk include renal failure, increasing number of medications, age ≥75 years and comorbidity conditions. Patients with a high GerontoNet risk scale ≥4 predicted to be exposed to ADRs approximately four times more likely than those with low GerontoNet risk scale (0-3) (odds ratio, 15.08; 95%CI 7.3–31.15) and so during hospital stay, (odds ratio, 3.103; 95% CI, 0.984–9.785). Conclusions: Polypharmacy is common among older people; this may be partly attributed to the high prevalence of multi-morbidity reported. Adverse reaction in older people can be assessed using GerontoNet, although the GerontoNet ADR risk score improperly classified 21.9% of patients as high risk. Review of appropriateness of medication use is essential, as polypharmacy places ageing people at risk of adverse effects.