Critical Illness Linked to Psychiatric Diagnosis

Critically ill patients on mechanical ventilation may be more likely to have psychiatric diagnosis

(RxWiki News) Doctors need to understand their patients' complete health history in order to treat them correctly. In patients with life-threatening conditions, even mental health history could be essential to ensuring a positive outcome.

A recent study found that patients with life-threatening conditions (critical illness) were more likely to have a history of psychiatric illness before being hospitalized than non-critically ill hospital patients and people from the general population.

The researchers discovered that the amount of newly diagnosed psychiatric disorders and prescribed psychoactive medications increased among the critically ill patients in the first few months after they left the hospital.

"Discuss your psychiatric history with your doctor."

The lead author of this study was Christian F. Christiansen, MD, PhD, from the Departments of Clinical Epidemiology Anesthesiology and Intensive Care of Aarhus University Hospital in Aarhus, Denmark.

The study included 24,179 critically ill, nonsurgical patients admitted to a Danish intensive care unit (ICU) between January 1, 2006 and December 31, 2008. Another 20,466 control patients were also included in the study. These controls were matched to the critically ill patients by date of hospital admittance, but not in the ICU, within 180 days of the critically ill participants.

In addition, there were 120,844 controls from the general population of Denmark and who were not in the hospital during the study period; these controls were matched by birth year and sex.

All participants were older than 15 years, but most were 65 years old or older. Over half of each group was male.

The researchers conducted follow-up through December 31, 2009. National medical databases were used to determine the prevalence of psychiatric diagnoses and psychoactive medication prescriptions in all groups.

The critically ill patients' hospitalization dates were used for reference when referring to time periods.

The findings showed that one year prior to hospitalization, the critically ill patients were more likely than the hospitalized control group and the general population control group to have been diagnosed with one or more psychiatric disorders by a psychiatrist.

The critically ill group was more likely than the hospitalized control group and more likely than the general population control group to have been diagnosed with at least one psychiatric condition in the five years prior to hospitalization.

The researchers found that 31 percent of the critically ill patients died before being discharged from the hospital. 

Among the critically ill patients who survived to hospital discharge, 59 percent did not have any history of a psychiatric condition or psychoactive medication use in the five years prior to hospitalization; yet, these survivors were at a 3.42 times increased risk compared to the hospitalized control group, and a 21.77 times increased risk compared to the general population control group, of being diagnosed with at least one psychiatric condition during the first three months after being discharged from the hospital.

The risk of the surviving critically ill patients being prescribed a psychoactive medication during the first three months after being discharged was 2.45 times greater than that of the hospitalized control group and 21.09 times greater than that of the general population control group.

The findings revealed that the risk of being diagnosed with a psychiatric condition or being prescribed a psychoactive medication evened out in the critically ill group and the hospitalized control group by nine to 12 months after hospital discharge.

However, the critically ill group still had a 63 percent increased risk for a psychiatric diagnosis and 2.08 times increased risk for a psychoactive medication prescription compared to the general population controls.

Dr. Christiansen and team suggested that psychiatric conditions might predispose patients to critical illness.

The researchers noted several limitations of their study. First, the researchers only evaluated patient's psychiatric histories during the five years prior to hospitalization. Second, the general population control group did not exclude people who may have been hospitalized at some point, just not during the time of the critically ill participants.

Third, survivors of critical illness usually have a significant risk of death in the six months to a year after discharge. Fourth, the researchers lacked specific data on the severity of the critical illness or type of medication administered while in the hospital. Lastly, the researchers may have underestimated the total burden of psychiatric illness because some patients may have been diagnosed or prescribed multiple times. Lastly, duration of medication use was not considered.

This study was published on March 18 in JAMA.

The Danish Medical Research Council, the Clinical Institute at Aarhus University and the Department of Clinical Epidemiology's Research Foundation at Aarhus University provided funding.

Review Date: 
March 18, 2014