More than half of patients who survive a critical illness requiring care in an intensive care unit suffer anxiety, PTSD or depression within a year after discharge.
The numbers of patients who suffer psychologically are greater than first thought, revealed an Oxford University study.
And when they suffer symptoms of one psychological condition, there is a 64 per cent chance they will co-occur with symptoms of another.
Those who are depressed have an increased risk of dying in the two years following discharge.
Scientists said ICU patients should be screened to spot those who may have the psychological disorders.
Dr Peter Watkinson, Associate Professor of Intensive Care Medicine, said: “Survivors of critical illness are at risk of experiencing significant physical, cognitive and psychological issues after discharge.
“New or worsening impairment in physical, cognitive or mental health status following treatment on an intensive care unit (ICU) is known as post-intensive care syndrome (PICS).
“The psychopathological components of PICS are estimated to occur in up to a third of survivors of ICU treatment.
“The major psychological conditions described are anxiety, depression and post-traumatic stress disorder (PTSD).”
So the researchers investigated psychological disorders in a cohort of 4,943 former ICU patients taking part in The Intensive Care Outcomes Network study (ICON) at one of 26 centres in the UK between 2006 and 2013.
They had at least 24 hours at level 3 ICU care and filled in a questionnaire on their symptoms of anxiety, depression and PTSD three months after discharge and again 12 months afterwards.
The objective was to describe the pattern of psychopathology occurring in survivors at three and 12 months following discharge from ICU and to assess any association with mortality.
They found that 46 per cent of patients reported symptoms of anxiety, 40 per cent reported symptoms of depression and 22 per cent reported symptoms of PTSD.
And 18 per cent reported symptoms of all three psychological conditions.
Prof Watkinson said: “Psychological problems after being treated for a critical illness in the ICU are very common and often complex when they occur.
“When symptoms of one psychological disorder are present, there is a 65 per cent chance they will co-occur with symptoms of another psychological disorder.”
Patients who reported symptoms of depression were 47 per cent more likely to die from any cause (all-cause mortality) during the first two years after discharge from the ICU than those who did not report these symptoms.
Prof Watkinson said: “Our study discovered a previously unknown association between symptoms of depression and increased mortality.
“This study also demonstrates that depression is associated with higher mortality rates for common medical conditions such as heart disease, respiratory illness, cerebrovascular disease, accidents, diabetes mellitus and hypertension.
“It remains unclear whether clinicians are overlooking the screening and treatment of depression in favour of treating chronic medical conditions or whether there is a biological association between chronic illness and depression.
“In the post-ICU population, the observed association between depression and mortality could be in part explained by the severity of chronic illness both pre-discharge and post-discharge, factors we did not adjust for in this study.
“However, to the best of our knowledge, an association between depression and an increased rate of mortality after discharge from ICU has not been demonstrated previously.
“Depression could be a factor not previously considered in post-ICU survival.
“Given the incidence of depression amongst survivors, symptoms of this condition should be detected and managed during the time following ICU in primary care and in ICU follow-up clinics.
“Our findings suggest that depression following care of a critical illness in the ICU may be a marker of declining health and clinicians should consider this when following up with former ICU patients.”
He noted because of the observational nature of the study and its reliance of self-reported data mean that it does not allow for conclusions about cause and effect between ICU care and symptoms of psychological disorders.
The study was published in the journal Critical Care.