Wobbly in more ways than one - antidepressants and postural hypotension

Beryl is an 82 year old lady presenting with a ‘muzzy head’.  ‘What do you mean by muzzy head’, you ask ‘Oh you know - just muzzy!’ she replies, giving you a slightly exasperated look. Hmmm… clear as mud, but a glance at the records shows that Beryl has recently been diagnosed with depression and started on sertraline. We generally think of SSRIs as the safest antidepressant choice in older people, with a much lower anti-cholinergic burden than with TCAs, but could the sertraline be a potential cause of her ‘muzzy head’?

On further questioning Beryl reports feeling a bit ‘wobbly’ when she stands up. She has lost balance on a few occasions, including one episode when she fell but thankfully without significant injury. You wonder about postural hypotension and lo and behold examination reveals a postural drop supine to standing in her BP from 135/85 to 110/70. 

So, could the sertraline be the cause of her postural hypotension? A new study from the BJGP Jan 25 suggests that it certainly could be. It examined the risk of postural hypotension associated with antidepressant use in older adults in the UK primary care population. The study included >41,000 adults over 60, with incident postural hypotension and antidepressant use between 2000 and 2018. They used a self-controlled case series design, comparing the risk of postural hypotension during specific periods of antidepressant exposure within each individual. The cases were therefore acting as their own control, allowing for inclusion of a complex population including those with co-morbidities and polypharmacy that may otherwise be excluded from RCTs. Antidepressants were examined in three groups: tricyclic antidepressants, SSRIs and other antidepressants (including mirtazapine, duloxetine and venlafaxine).

They results showed a striking increase in the risk of postural hypotension in the first 28 days after initiation of all antidepressants. This was most pronounced in the SSRI group, with over a four-fold risk seen in the first 28 days of initiation (incident rate ratio of 4.22 (95% CI: 3.76-4.74)). Fortunately, the risk was observed to reduce over time with an IRR during the continuation period of 1.62 (95% CI 1.50-1.77).  Interestingly, they also found an increased risk of postural hypotension during the 90-day pre-exposure period for SSRIs and ‘other antidepressants. The authors hypothesise that this could demonstrate a background risk of postural hypotension related to depression. 

As with any observational study, there are potential confounding factors here, including a lack of control for potential exposure to additional new medications or development of new clinical conditions. However, the results support previous guidance on the risks of postural hypotension associated with all antidepressants including SSRIs  in older people (SPS).

You and Beryl conclude that the sertraline is the most likely culprit for her postural hypotension. You explain that the research suggests it will improve with time, but on balance you both decide that the risks and potential consequences of another fall are too high, so you decide to deprescribe and look at other non-pharmacological options for managing her depression.

The take home message from this paper is that we should be particularly alert to the risk of postural hypotension in the first few weeks after starting any antidepressant, particularly SSRIs in older patients. We should discuss potential symptoms prior to initiation and consider monitoring older patients for postural hypotension soon after starting, especially if they have any additional risk factors such as other meds or co-morbidities which may contribute to it.