Elsevier

The Lancet

Volume 351, Issue 9106, 21 March 1998, Pages 857-861
The Lancet

Articles
Long-term postoperative cognitive dysfunction in the elderly: ISPOCD1 study

https://doi.org/10.1016/S0140-6736(97)07382-0Get rights and content

Summary

Background

Long-term postoperative cognitive dysfunction may occur in the elderly. Age may be a risk factor and hypoxaemia and arterial hypotension causative factors. We investigated these hypotheses in an international multicentre study.

Methods

1218 patients aged at least 60 years completed neuropsychological tests before and 1 week and 3 months after major non-cardiac surgery. We measured oxygen saturation by continuous pulse oximetry before surgery and throughout the day of and the first 3 nights after surgery. We recorded blood pressure every 3 min by oscillometry during the operation and every 15–30 min for the rest of that day and night. We identified postoperative cognitive dysfunction with neuropsychological tests compared with controls recruited from the UK (n=176) and the same countries as study centres (n=145).

Findings

Postoperative cognitive dysfunction was present in 266 (25·8% [95% CI 23·1–28·5]) of patients 1 week after surgery and in 94 (9·9% [8·1–12·0]) 3 months after surgery, compared with 3·4% and 2·8%, respectively, of UK controls (p<0·0001 and p=0·0037, respectively). Increasing age and duration of anaesthesia, little education, a second operation, postoperative infections, and respiratory complications were risk factors for early postoperative cognitive dysfunction, but only age was a risk factor for late postoperative cognitive dysfunction. Hypoxaemia and hypotension were not significant risk factors at any time.

Interpretation

Our findings have implications for studies of the causes of cognitive decline and, in clinical practice, for the information given to patients before surgery.

Introduction

Early postoperative cognitive dysfunction, confusion, and delirium are common after major surgery in the elderly.1, 2 Previous studies and anecdotal reports suggest that symptoms may persist in some patients for months or years.3 Events such as anaesthesia may contribute to agerelated cognitive decline, even when they occurred many years previously.4 Long-term postoperative cognitive dysfunction can occur after cardiac surgery, but the cause was thought to be the cardiopulmonary bypass.5, 6 The prevalence, causes, risk factors, and consequences of long-term postoperative cognitive dysfunction after non-cardiac surgery are unknown.

The monitoring of oxygen saturation has shown that hypoxaemia is most severe during nights 2 and 3 after surgery.7 Studies to characterise risk factors, to identify the deleterious effects of hypoxaemia on the heart, brain, and other organs, and to clarify the influence of hypoxaemia on outcome after surgery have been called for.8

In a multicentre study (the International Study of Post-Operative Cognitive Dysfunction [ISPOCD 1]), we investigated the occurrence of long-term postoperative cognitive dysfunction in elderly patients after major abdominal and orthopaedic surgery. We assessed the role of age as a major risk factor, and the causative roles of hypoxaemia and hypotension.

Section snippets

Methods

The protocol was approved by the research ethics committees in the centres and all patients gave written informed consent.

13 hospitals in eight European countries and the USA recruited patients to the study by the same protocol. Eligible patients were aged at least 60 years, had presented for major abdominal, non-cardiac thoracic, or orthopaedic surgery under general anaesthesia between Nov 1, 1994, and May 31, 1996, and expected a hospital stay of at least 4 days. We gave priority to patients

Results

We enrolled 176 UK controls, 145 national controls and 1218 patients. 271 (22%) patients did not complete the assessment at 3 months because of refusal to participate (118) and death (57). Those who withdrew did not differ significantly in any characteristics from those who continued in the study. The age, sex distribution, and other characteristics of the patients and the UK controls were similar (table 1).

At 7 days (5th-95th percentile 4–19) after surgery, we found cognitive dysfunction in

Discussion

We confirmed unequivocally that anaesthesia and surgery cause long-term postoperative cognitive decline in the elderly and that the risk increases with age. However, neither hypoxaemia nor hypotension was related to the risk. We were unable to find any specific risk factors to which therapeutic or preventive measures could be directed and we could not elucidate the pathophysiology of postoperative cognitive dysfunction any clearer.

Cerebral hypoxia can lead to severe brain damage, but the degree

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