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Depression, post-traumatic stress disorder, and functional disability in survivors of critical illness in the BRAIN-ICU study: a longitudinal cohort study

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Summary

Background

Critical illness is associated with cognitive impairment, but mental health and functional disabilities in survivors of intensive care are inadequately characterised. We aimed to assess associations of age and duration of delirium with mental health and functional disabilities in this group.

Methods

In this prospective, multicentre cohort study, we enrolled patients with respiratory failure or shock who were undergoing treatment in medical or surgical ICUs in Nashville, TN, USA. We obtained data for baseline demographics and in-hospital variables, and assessed survivors at 3 months and 12 months with measures of depression (Beck Depression Inventory II), post-traumatic stress disorder (PTSD, Post-Traumatic Stress Disorder Checklist—Event Specific Version), and functional disability (activities of daily living scales, Pfeffer Functional Activities Questionnaire, and Katz Activities of Daily Living Scale). We used linear and proportional odds logistic regression to assess the independent associations between age and duration of delirium with mental health and functional disabilities. This study is registered with ClinicalTrials.gov, number NCT00392795.

Findings

We enrolled 821 patients with a median age of 61 years (IQR 51–71), assessing 448 patients at 3 months and 382 patients at 12 months after discharge. At 3 months, 149 (37%) of 406 patients with available data reported at least mild depression, as did 116 (33%) of 347 patients at 12 months; this depression was mainly due to somatic rather than cognitive–affective symptoms. Depressive symptoms were common even among individuals without a history of depression (as reported by a proxy), occurring in 76 (30%) of 255 patients with data at 3 months and 62 (29%) of 217 individuals at 12 months. Only 7% of patients (27 of 415 at 3 months and 24 of 361 at 12 months) had symptoms consistent with post-traumatic distress disorder. Disabilities in basic activities of daily living (ADL) were present in 139 (32%) of 428 patients at 3 months and 102 (27%) of 374 at 12 months, as were disabilities in instrumental ADL in 108 (26%) of 422 individuals at 3 months and 87 (23%) of 372 at 12 months. Mental health and functional difficulties were prevalent in patients of all ages. Although old age was frequently associated with mental health problems and functional disabilities, we observed no consistent association between the presence of delirium and these outcomes.

Interpretation

Poor mental health and functional disability is common in patients treated in intensive-care units. Depression is five times more common than is post-traumatic distress disorder after critical illness and is driven by somatic symptoms, suggesting approaches targeting physical rather than cognitive causes could benefit patients leaving critical care.

Funding

National Institutes of Health AG027472 and the Geriatric Research, Education and Clinical Center (GRECC), Department of Veterans Affairs Medical Center, Tennessee Valley Healthcare System.

Introduction

At least 5 million individuals are admitted to medical or surgical critical care units in North America every year—more than are diagnosed with cancer—and about 80% survive.1, 2 For these patients, critical illness can be a gateway to post-intensive care syndrome,3 which includes cognitive impairment, depression, post-traumatic stress disorder (PTSD), functional disabilities, and decrements in quality of life.4, 5, 6, 7, 8, 9

These outcomes have been studied in some critically ill populations (eg, patients with sepsis or acute respiratory distress syndrome), but typically only within a narrow age range of individuals, and they have rarely been assessed in general cohorts of patients in medical or surgical intensive care units (ICUs).10, 11 A third of survivors of acute respiratory distress syndrome are reported to have depression,4 but the precise nature of their symptoms or those of survivors of medical and surgical ICUs is unknown. Symptoms of post-traumatic distress disorder have been reported in up to half of survivors of critical illness,5 but prevalence according to Diagnostic and Statistical Manual (DSM) criteria in general medical and surgical populations is also unknown, particularly in the specific context of critical illness as a traumatic stressor.5 Functional disability in survivors of critical care from causes other than acute respiratory distress syndrome is poorly understood, although it has been assessed in some other specific contexts (eg, patients with sepsis).12 Finally, few investigations have explored delirium related to ICU admission—which is a potentially modifiable risk factor—in the emergence of mental health problems and functional difficulties.4, 5, 13

We aimed to characterise mental health outcomes and functional disabilities in a general ICU population and to explore the hypothesis that depressive symptoms after discharge are more often somatic (ie, bodily complaints) than cognitive–affective (ie, thought-related and mood-related complaints). We also aimed to test the effects of age across outcomes, with the hypothesis that younger patients have much the same symptoms of depression, PTSD, and functional disability as do older patients. Finally, we sought to determine if delirium is a risk factor for poor mental health and functional outcomes at 3 month and 12 month follow-up, testing the hypothesis that delirium is associated with depression, PTSD, and functional disabilities.

Section snippets

Study design and patients

In our prospective, observational cohort study, we screened adults aged at least 18 years with respiratory failure, cardiogenic shock, or septic shock who were admitted to medical or surgical ICUs at Vanderbilt University Medical Center or Saint Thomas Hospital (both Nashville, TN, USA). We excluded individuals who had been mechanically ventilated at any time in the 2 months before admission, spent more than 5 days in an ICU during the month before admission, or spent more than 72 h with organ

Results

We enrolled 826 patients between March 1, 2007, and June 30, 2010. Five patients withdrew consent and permission to use collected data; thus, we had 821 patients with in-hospital data and assessments. Of 10 558 days spent in the hospital by our patients, we did at least one complete mental assessment (delirium and coma) on 10 214 days (97%), thus only 3% of days were missing assessments. Between enrolment and 3 month follow-up, 252 (31%) patients died; 448 (79%) of 569 surviving patients

Discussion

Our large prospective cohort investigation yielded two main sets of observations related to mental health and functional outcomes in ICU survivors (panel). First, we noted that depression was five times more frequent than was post-traumatic distress disorder in ICU survivors, and its symptoms were most often driven by somatic rather than cognitive–affective components. Second, we noted that patients in this large cohort (including many with no reported history of psychiatric treatment) had

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