Decreased Risk of Psychiatric Readmission After ECT: New Swedish Register Study in Acta

Out on PubMed, in Acta Psychiatrica Scandinavica, is this study:

Electroconvulsive Therapy and Psychiatric Readmission in Major Depressive Disorder - A Population-Based Register Study.

Stenmark L, Kellner CH, Landén M, Larsson I, Msghina M, Nordenskjöld A.Acta Psychiatr Scand. 2021 Sep 15. doi: 10.1111/acps.13373. Online ahead of print.PMID: 34523119

The abstract is copied below:

Objective: The primary aim was to determine whether electroconvulsive therapy (ECT) is associated with reduced risk of psychiatric readmission in major depressive disorder (MDD).

Methods: This study was based on data from multiple Swedish population-based registries. All adult patients admitted to any Swedish hospital for moderate-to-severe MDD between 2012-2018 were included. Participants were divided into two groups depending on whether they received ECT during inpatient care. Follow-up was set at 30 and 90 days from discharge. Data were analyzed using logistic regression and matching was conducted.

Results: A total of 27,851 unique patients contributed to 41,916 admissions. ECT was used in 26.8% of admissions. In the main multivariate analysis, the risk of both 30- and 90-day readmission was lower in the ECT group than in the non-ECT group. In a matched sensitivity model, the results pointed in the same direction for readmission risk within 30 days, but statistical significance was not reached. ECT-treated subgroups with superior outcomes on readmission risk compared to non-ECT treatment were older, unemployed, married, or widowed patients, those treated with antipsychotics or benzodiazepines before admission, with psychotic features, prior psychiatric hospitalizations, or family history of suicide. However, in patients below 35 years of age, ECT was associated with increased readmission risk.

Conclusion: This study suggests that ECT reduces the risk of psychiatric readmission in certain subgroups of patients with MDD. Since patients receiving ECT tend to be more difficult to treat, there is risk of residual confounding.

Keywords: Electroconvulsive Therapy; Major Depressive Disorder; Patient Readmission; Risk Factors.

And from the text:

Discussion:

The results of this study support that ECT reduces the risk of psychiatric readmission in certain subgroups of patients with MDD. In the main analysis, ECT was associated with reduced overall risk of both 30- and 90-day readmission in a multivariate model when compared to non-ECT treatment. The association of ECT on readmission risk, however, were not as pronounced as in previous studies with positive results [13,14]. Furthermore, although the results of both sensitivity analyses pointed in the same direction as the main analysis for readmission risk within 30 days, statistical significance was not reached in these analyses. This could be explained by insufficient power, as fewer study participants were included in these models, and that the association was unevenly distributed across subgroups with a modest overall effect. Moreover, there is risk of residual confounding. Therefore, there is still some uncertainty regarding to what degree ECT reduces the risk of psychiatric readmission in MDD. Having residual symptoms after treatment is a well-established risk factor for relapse and recurrence in MDD [5]. The likely explanation of the superior outcomes of certain subgroups treated with ECT compared to those receiving non-ECT treatment is that the ECT-treated patients had fewer and less severe symptoms at discharge (i.e. were more effectively treated). This is in line with other studies which have shown ECT to be more effective than pharmacotherapy for the treatment of inpatients with depressive illness [17]. Study participants treated with ECT for severe MDD with psychotic features were less likely to be readmitted than patients with the same diagnosis receiving non-ECT treatment in multivariate stratification and interaction analyses. By contrast, there was no statistically significant difference in readmission risk between study participants treated with ECT and those receiving non-ECT treatment in moderate-to-severe MDD without psychotic features. There is evidence supporting ECT as especially effective in preventing relapse and readmission in MDD with psychotic features [10,27,28]. Depressed patients in ECT trials have previously been described to be more severely ill than those participating in pharmacotherapy trials [29]. At the time of admission, the ECT group had more severe symptoms than the non-ECT group. Greater severity of illness has previously been associated with increased risk of relapse and readmission in MDD [30,31], and was also found to predict increased risk of both 30- and 90-day readmission in the present study. Although we did adjust for depression severity as diagnosed with ICD-10, it is likely that within each diagnostic category, the ECT group tended to have more severe symptoms than the non-ECT group. If this was the case, the true effects of ECT on readmission risk is in fact likely to be underestimated in our models. There was a strong correlation between a higher number of prior psychiatric hospitalizations and increased readmission risk in all analyses. To date, there is stronger evidence supporting a history of prior depressive episodes being associated with increased risk of relapse or recurrence than the specific number of prior depressive episodes or hospitalizations [5]. However, some studies have found a higher number of prior psychiatric hospitalizations to correlate with increased readmission risk in patients with MDD [10,32,33]. Additionally, some other studies have found a higher number of prior episodes to correlate with increased risk of recurrence [34-36]. Study participants with a history of prior psychiatric hospitalizations had decreased risk of readmission in multivariate stratification and interaction analyses, especially within 30 days, when treated with ECT compared to those receiving non-ECT treatment. Patients without prior admissions did not have a significantly reduced readmission risk when treated with ECT. These results indicate that ECT is an especially suitable choice for patients with severe and recurrent depressive episodes.

Age was negatively associated with readmission risk in all analyses. In multivariate stratification and interaction analyses, older age was consistently associated with reduced risk of both 30- and 90-day readmission in study participants treated with ECT compared to the same subgroups receiving non-ECT treatment. Furthermore, younger age was associated with increased readmission risk in patients treated with ECT compared to non-ECT treatment. ECT has been found to be especially effective in older patients [37]. Psychotic symptoms and psychomotor retardation are more common in older individuals, and patients with such symptoms tend to respond better to ECT, which could explain the results of the present study [38,39]. To date, there is sparse evidence supporting that older patients have decreased risk of readmission after ECT [40], and that younger individuals are at increased risk when compared to older patients treated with ECT [10]. The increased readmission risk in younger individuals treated with ECT in the present study could perhaps be explained by residual confounding. Nevertheless, a meta-analysis of 372 randomized placebo-controlled antidepressant drug trials found the risk of suicidal ideation and suicidal behavior (preparation, attempted suicide, or completed suicide) associated with antidepressant use to be strongly age-dependent. Increasing age was associated with a protective effect [41]. Age-dependent associations of ECT on readmission risk and of antidepressant drugs on suicidality could possibly be explained by differences in underlying disease mechanisms. Most factors associated with readmission risk in the present study have been previously described to predict relapse or recurrence, including having a comorbid personality disorder [42], anxiety disorder [5], or higher ATHF score [10]. To the best of our knowledge, no previous study has found having a higher education level or being voluntarily admitted to correlate with decreased risk of readmission, or having collected antipsychotics or benzodiazepines within 100 days before admission to be associated with increased readmission risk. However, some studies have found a similar association for such drugs collected after discharge [10,43]. Study participants prescribed drugs other than antidepressants or lithium perhaps represent a subset of patients difficult to treat and, therefore, more likely to be readmitted. Nevertheless, when these study participants were treated with ECT, they were less likely to be readmitted than similar patients receiving non-ECT treatment. These results suggest that ECT is a valid option for such patients. There were several other subgroups with decreased risk of readmission when treated with ECT compared to non-ECT treatment. Patients who were married, widowed, or unemployed were less likely to be readmitted after ECT. It has been suggested that family history of affective disorders or suicide should be considered when selecting appropriate candidates for ECT [44], and in this cohort family history of affective disorders was more common in the ECT group than in the nonECT group. This study could neither confirm nor refute differential effects of ECT on readmission risk among patients with or without family history of affective disorders. However, family history of suicide was associated with decreased risk of readmission in study participants treated with ECT compared to those receiving non-ECT treatment. Therefore, it could be appropriate to ask about family history when considering a patient for ECT. These patients could perhaps represent a subset of patients with more severe family history of psychiatric disorders. To the best of our knowledge, no previous study has identified family history of suicide to be predictive of response, remission, nor readmission in MDD. Further studies are needed to investigate potential differential effects of ECT in patients with family history of suicide, psychiatric disorders, or specific genetic factors. This study shows considerable risk of readmission after inpatient treatment for MDD in patients treated with and without ECT. In addition to treatment with antidepressants, which most patients had been prescribed, lithium [8,45] and continuation ECT have been shown to reduce the risk of relapse in MDD [46,47]. There was an association between reduced readmission risk and continuation ECT after discharge in this study. A small minority of study participants had these treatments; outcomes could likely be improved by more systematic use of lithium and continuation ECT. To date, this is one of largest studies to have investigated whether ECT reduces the risk of psychiatric readmission in MDD compared to non-ECT treatment. The large sample is facilitated by the high rate of ECT use in Sweden and the existence of national registries [20]. Patients treated at all Swedish hospitals were included. Nonetheless, there were several limitations to this study. Substantial differences have been reported in previous studies between patients treated with ECT and those receiving non-ECT treatment [48]. Similar differences were also found in the present study, limiting the comparability between the groups. Matching was conducted to minimize these differences, but made each group considerably smaller and reduced the statistical power. Potential confounders were identified through a literature search. However, some of these factors were not accessible in register data and could not be included in the analyses, such as childhood maltreatment, age of onset, and medication compliance. Even though ECT can be delivered in an outpatient setting, most patients in Sweden receive their index series in an inpatient setting. This could have increased the readmission risk among ECT-treated patients. A few individual patients received a very high number of ECT sessions in their treatment series, suggesting unusually severe and persistent symptoms. Such patients are so unusual that statistical adjustment becomes uncertain. However, as they are so few their overall impact of the results is small. Only a minor proportion of patients received continuation ECT after their index series, and these patients are likely to differ from other patients in regard to previous response to pharmacotherapy or ECT and perceived risk of relapse as assessed by the treating psychiatrist. Further studies are required to adequately assess the effects of continuation ECT on readmission risk. Finally, the diagnoses were made in clinical practice, which means that there may be some uncertainty in the classifications. For instance, it is probable that a small subset of patients with bipolar disorder were included in this study despite the fact that patients with prior admissions for mania were excluded. This study suggests that ECT reduces the risk of psychiatric readmission in certain subgroups of patients with MDD. ECT-treated subgroups with superior outcomes on readmission risk compared to non-ECT treatment were older, unemployed, married, or widowed patients, those treated with antipsychotics or benzodiazepines before admission, with psychotic features, prior psychiatric hospitalizations, or family history of suicide. However, in patients below 35 years of age, ECT was found to be associated with increased readmission risk. This study is limited by the risk of residual confounding, especially since patients treated by ECT tend to have more severe symptoms and are more difficult to treat.

This is yet another interesting register-based study from Swedish data, and I am grateful to Axel and Linnea for including me in the work. While the results are not overwhelmingly positive, they are important and instructive, and should lead to further investigation of unanswered questions. Certainly the idea that greater use of maintenance ECT and lithium would lead to further decreases in readmissions is intriguing. There are lots of interesting data in the tables here, and I hope many ECT researchers and practitioners will look at them in detail. 

Yes, I am biased, but I suggest a full read for all ECT researchers and interested practitioners, ~25 minutes.