9. DISCUSSION ON ADVERSE EVENTS AND RISK

ECT is a low risk procedure and is a common choice for patients with severe medical illness because of its speed of action and low side-effect profile. However, as with all procedures involving an anaesthetic, each patient should undergo a pre-treatment risk to benefit assessment taking account of the effect of:

• a pre-existing medical condition
• the anaesthetic
• the electrical stimulus
• the seizure
• the age of the patient

If at all possible appropriate treatment of any underlying condition should be given prior to ECT. The overall complication rate increases with age, severity of medical condition and number of concurrent medications being in the region of 18% for the under 60 years rising to 35% for those over 60 years (Burke et al 1987). However, depression in the elderly may be more resistant to medication and there are reports that ECT has a superior therapeutic effect in this age group (Sackeim 1998).

Depressive illness, especially in males, carries a significant mortality rate independent of other variables (Murphy 1988). Completed suicide by patients with depressive disorder rises to 20 times the background rate (King 1994) and it is estimated that between 7 to 15% of patients with depression will eventually commit suicide (Inskip 1998, Guze 1970). Treatment with ECT has been shown to exert a profound short term beneficial effect on suicidality (Prudic 1999).

The risk of death at ECT of 2 per 99,425 treatments puts ECT at the bottom of the range for anaesthesia alone (Fink 1979) and there is evidence that the mortality rate is falling (Abrams 1992). There is a lack of outcome data on mortality extending beyond the first 24 hours post treatment but Philibert et al (1995) found that geriatric patients who had received ECT were more likely to be alive at follow up. There is no evidence that antidepressants are safer and one study found a seventeen times higher than normal rate of fatal myocardial infarction in young women on tricyclic antidepressants (Thorogood et al 1992).

The most likely serious complications at ECT involve the cardiovascular (CVS) and central nervous (CNS) systems and these will lead to the termination of treatment in around 5% of courses (Ziesinskly et al 1993). The same study showed a rate of discontinuation of tricyclic antidepressants as high as 52%.

The most common cognitive side effect leading to discontinuation of treatment is acute confusion (Sackeim 1987). Short term memory impairment around the course of ECT is very common with at least one study reporting that 64% of patients experience some form of memory problem (Freeman 1980). However, memory recovers gradually and the majority of patients report an improvement in cognitive function at two months post treatment (Coleman 1996).

The fact that the audit did not set out to record all the side effects at ECT explains the low rate of recording of adverse events. The audit forms asked for a reason for any ECT course not completed as planned. As such the answers given were not always specific and an attempt to classify them was made as per tables 10 and 20 with more detailed information on adverse events described in table 21 below. During the audit it was agreed by ECT consultants that more detailed information on serious side-effects should be included on a national database as an on-going project.

The studies quoted for comparison are the most representative we have found in the literature. They are not always directly comparable; for example the Burke 1987 refers to an elderly population only.

Table 21: Adverse events at ECT: Reasons for discontinuation of treatment