Polypharmacy in a general surgical unit and consequences of drug withdrawal

Abstract

AIMS: To identify drug usage/withdrawal in surgical patients and the relative risk this imposes on postoperative surgical complications. METHODS: A prospective survey of patients' medicines, oral intake (food/fluids/ medicines) and postoperative complications was carried out in the General Surgical Unit, Dunedin Hospital, Dunedin, New Zealand. RESULTS: One thousand and twenty-five general surgical patients aged >/= 16 years, were entered into the study. Half of the patients were taking medicines unrelated to surgery. On average these patients received 9 different drugs (range 1-47) from a selection of 251, of which 21% were released in the last 10 years. The mean number of these drugs taken increased with age, vascular surgery and other major procedures. The majority of patients (53%) were taking drugs for cardiovascular problems. Only 8% of admissions were on the drugs more traditionally recognized to be of importance to the surgery, i.e. steroids and diabetic therapy. With respect to risk, taking a drug unrelated to surgery was associated with an increased relative risk of a postoperative complication by 2.7 (95% C.I. 1.76-4.04) compared with those who were not taking any drug. Cardiovascular drugs contributed significantly to this risk; when they were excluded from analysis, the risk dropped to 1.8 (95% C.I. 1.14-2.93). Death may be more common in those taking ACE inhibitors. Drug withdrawal and complications were analysed and as the time without medicines increased (range 1-42 days) so did the complication rate (chi2 = 14.7, DF = 2, P = 0.007). Of those patients who were taking a cardiovascular medicine and were without their normal medicines for a period of time postoperatively, 12% suffered a cardiac complication. CONCLUSIONS: Many patients admitted to a general surgical ward, are taking medicines unrelated to surgery. Drug therapy unrelated to surgery is a useful predictor for increased postoperative complications and one for which preventive action can be taken. This study provides evidence that withdrawal of regular medicines may add significant risk to the surgery and further complicate outcome. The longer patients were without their regular medicines the more nonsurgical complications they suffered. Reintroduction of patients' regular medicines early in their postoperative course may decrease morbidity and mortality in-patients.