What are the real costs of rTMS?

Recently, the Australian government has committed a significant amount of funding to the provision of repetitive transcranial magnetic stimulation (rTMS) for the management of patients with ‘treatment-resistant depression’. A fundamental problem is that the evidence for the efficacy of this intervention is still very much in its infancy. Indeed, as has been argued in this journal, and illustrated through a number of incisive articles published in this journal in recent months, the jury is very much out as to whether there is a meaningful signal with rTMS delivery in the treatment of depression (Malhi et al., 2021b, 2021c).

In line with the recommendations of the recently published RANZCP Clinical Practice Guidelines for mood disorders, many others have raised concerns regarding the use of TMS (Amad et al., 2019), questioning its antidepressant properties (Malhi et al., 2021b) and in particular, the extent to which any response to rTMS is specific to the intervention – as opposed to being the result of non-specific and placebo effects, which have been shown to be significant (Malhi and Bell, 2021).

Notably, proponents of rTMS have been unable to mount convincing scientific responses to these questions and have failed to identify the kind of depression, if any, that is best suited to rTMS, and what parameters ought to be used to achieve meaningful outcomes.

When the efficacy of rTMS is questioned, a common response is that because rTMS is highly tolerable, there is no harm in trying it. But, this is not true. In addition to the financial costs, which are considerable and where it is clear that rTMS is extremely expensive, its real costs that are clinical have been overlooked and remain unexplored. In this brief article we outline the real costs of rTMS, in other words, its direct and indirect ‘hidden’ clinical costs and, in particular, its potential harms.

The reality is that rTMS is being offered to depressed patients with a serious illness, one which confers enormous disability and runs the risk of suicide, and therefore prompt, effective therapy is a must. In these instances, offering treatment that lacks proven efficacy means that patients are likely to continue to suffer. But in addition to the emotional burden of the illness, it is important to recognise that the disorder continues to negatively impact the brain. We now know that depression leads to structural changes in the brain and that the illness severely compromises its functioning (Moylan et al., 2013). Furthermore, this is more pronounced during acute episodes of depression. Therefore, offering a therapy that is unlikely to be of benefit comes at a significant cost to the individual, as it allows the illness to inflict further adverse impact on the brain. This is the first hidden cost (see Figure 1: Neural damage because of depressive illness).

Figure 1.

The hidden costs associated with rTMS in the management of depression.

The second cost that is also ‘hidden’, because it is less obvious, is a significant opportunity cost. The time engaged in a treatment such as rTMS, involving for example daily visits, is extremely demanding and intensive. It adds to the enormous burden that a depressed patient has to endure; especially since this time could instead have been used to undergo a more effective alternative. As mentioned above, prompt treatment is essential, and therefore, by not offering the best treatment that is available, there is a considerable cost of lost opportunity. Drawing a parallel with cancer, it would be unconscionable to sit back and do nothing or offer a therapy with little hope of therapeutic benefit simply because it is well-tolerated. Furthermore, while tolerability is only relevant while treatment is ongoing, the adverse effects on the brain of not treating depression are likely to be more enduring and may even be irreversible and lifelong. In other words, it is imperative that at every juncture in the management of depression, the best available therapy is prescribed and that the fastest route to recovery is pursued. Trialling treatments simply because they are tolerable and therefore incorrectly thought to be safe is not acceptable practice.

Therefore, it can be seen that naïvely arguing that an intervention or therapy is tolerable, while not demonstrating its efficacy, does actually have a significant cost. This indirect cost is twofold and the first of these is literally hidden from view as it concerns the pathophysiological toll that depression inflicts on the brain because of not adequately treating the illness and leaving it unchecked. The second hidden cost is the fact that an alternative effective therapy could have been administered instead of rTMS and this may well have produced a clinically meaningful response and alleviated the burden of the acute episode of depression.

In addition to these clinically important indirect costs, the direct financial cost is a separate consideration, but one which again falls in favour of not providing an expensive treatment for which a clinical phenotype is not readily apparent. This is because without a clinical phenotype, a treatment can be administered indiscriminately to all manner of presentations.

Thus, the real costs of rTMS are very significant and the issue should be of grave concern to all. A failure to address this issue is likely to lead to a loss of trust in the therapeutic relationship that is core to psychiatry and threaten the integrity of the profession as a whole.