(NaturalNews) One in every five patients readmitted to the hospital within a year of an inpatient treatment ends up there because of an adverse drug reaction, according to a study conducted by researchers from the Royal Liverpool and Broadgreen University Hospitals NHS Trust.The research was presented at the British Pharmaceutical Conference in Manchester and published in the"While medicines have lots of benefits, they can also have harmful side-effects resulting in re-admission to hospital" researcher Emma Davies said. "Managing this involves checking patients' medicines while they are in hospital and regularly reviewing prescriptions in primary care after patients are discharged."Researchers examined data from approximately 1,000 patients who had been admitted to a large Liverpool hospital. Among the 290 patients who were readmitted within one year and for whom data were available, 21 percent had been readmitted at least partly because of an adverse drug reaction.The researchers defined an adverse drug reaction as "an appreciably harmful or unpleasant reaction, resulting from an intervention related to the use of a medicinal product, which predicts hazard from future administration and warrants prevention or specific treatment, or alteration of the dosage regimen, or withdrawal of the product."After analyzing each case, the researchers concluded that 57 percent of the adverse drug reactions probably or definitely could have been prevented. The most common side effects resulting in readmission were reactions to aspirin (prescribed to prevent heart attacks or strokes) or diuretics (prescribed for the treatment of high blood pressure or heart failure).Not all drug reactions in the study caused hospital readmission, but all required medical treatment. A total of 73.3 percent were classified as low severity, necessitating only minor treatment; 24.7 percent were classified as moderate, requiring a moderate increase in treatment but causing no lasting damage; 1.91 percent were classified as severe, causing permanent harm, and 0.14 percent were catastrophic, directly leading to a patient's death.Sources for this story include: www.medicalnewstoday.com;