Drug Therapy Can Predict Complications in Surgical Patients, Study Suggests
Little attention has been paid to the types of drugs patients have been taking before surgery and the consequences of abruptly withdrawing them, according to the authorspharmacy and medical school faculty members in New Zealand. To assess the amount and type of drug use in surgical patients and determine the relationship of drug use and drug withdrawal to postoperative complications, they studied the medication history, oral intake, and complications of patients admitted for 1025 surgical procedures.
Patient age ranged from 15 to over 90 years, but 50% of the patients were 60 or older. Drug therapy, the authors noted, has helped to improve the general well-being of older patients and allowed them to be considered for
On admission, the patients were receiving an average of 9.4 medications; the number ranged from 1 to 47. Half of the patients were taking drugs not related to their surgery; a majority of these patients were taking drugs for cardiovascular disease. Other types of drugs commonly used were central nervous system agents (tranquilizers, antidepressants, and
sedativehypnotics) and gastrointestinal agents. Few of the patients were taking drugs that "surgeons immediately recognize as posing problems" for postoperative management, such as insulin, warfarin, and corticosteroids, said the authors.
Complications occurred in 235 cases. A total of 373 complications were analyzed to determine (1) whether the patient's non-surgery-related drug therapy was a predictive factor for the complication and (2) whether withdrawal of the patient's regular drug therapy contributed to the complication.
Taking a drug unrelated to the surgery had an increased relative risk of complication of 2.7. When cardiovascular drugs were excluded, the relative risk was only 1.8.
The risk of complications increased in proportion to the amount of time without medications. Patients who had been taking a cardiovascular drug and went without the drug for up to two days had a complication rate of 12%. In case studies of selected patients, all complications resolved when the patient's regular medications were resumed.
"Admission drugs are a predictive factor for developing postoperative complications as they mask the predisposing frailty of many of these patients," the authors concluded. When this frailty is "unmasked" by drug withdrawal, nonsurgical postoperative complications increase; the stress of surgery is superimposed on the underlying pathology, "now without its normal pharmacological support."
In preoperative assessment and postoperative care, more attention is needed to patients' regular drug therapy, said the authors. They suggested that pharmacists monitor drug withdrawal and "alert the surgical team to therapeutic options."
An editorial in BMJ2 noted the importance of the study and echoed its call for guidance from pharmacists. The editorialists also said industry and regulatory agencies should provide more information on managing withdrawal of oral drug therapy.
- Kennedy JM, van Rij AM, Spears GF et al. Polypharmacy in a general surgical unit and consequences of drug withdrawal. Br J Clin Pharmacol. 2000; 49:353-62.
- Nobel DW, Kehlet H. Risks of interrupting drug treatment before surgery. BMJ. 2000: 32:719-20. Editorial.