Hospital Discharge Study Gives New Overview of Schizophrenia and Comorbidity

Kathryn Foxhall

May 09, 2008

May 9, 2008 (Washington, DC) — A study analyzing data from 5.7 million records in the US National Hospital Discharge Survey has underscored that schizophrenia patients are more likely to have 1 or more of a host of comorbid conditions, including both psychiatric and nonpsychiatric disorders, than those without schizophrenia.

Their study was presented here at the American Psychiatric Association 161st Annual Meeting.

Researchers working in coordination with the Department of the Army found, for example, that schizophrenia patients were 2.5 times more likely to have acquired hypothyroidism and 2.1 times more likely to have obesity or hyperalimentation problems. They are also 70% more likely to have chronic airway obstruction, not otherwise classified.

Natalya Weber, MD, an epidemiologist with Allied Technology Group, is a study coauthor, working with researchers at Walter Reed Army Institute of Research on this project. She told Medscape Psychiatry that although many of these individual conditions have been studied for increased incidence in schizophrenic patients, this research looks at comorbid conditions across the board. She does not believe this has been done previously with the National Hospital Discharge Survey.

"A closer attention to prevention, early diagnosis, and treatment of comorbid conditions may decrease medical morbidity and mortality and improve schizophrenia prognosis," the researchers conclude.

Comorbid Conditions

The annual survey by the National Center for Health Statistics gathers a national sample of hospital discharges. The records included in this study on schizophrenia patients were sampled to represent 835 million discharges between 1979 and 2003.

This analysis also found schizophrenic patients were 5 times more likely to have diagnosis of dermatophytosis, 3 times more likely to have poisoning by a psychotropic agent, 2.7 times more likely to have diseases of the sebaceous gland, and about twice as likely to have epilepsy, symptoms concerning nutrition, metabolism, and development; symptoms involving nervous and musculoskeletal symptoms; or a chronic bronchitis diagnosis.

Some conditions for which the study found increased rates had not been previously researched because they were not major diseases, said Dr. Weber.

She also noted, though, that the diagnosis rate for some conditions was lower in these discharge records than in studies that have examined specific comorbid conditions, possibly indicating conditions are being missed. For example, she said, the diabetes type 2 diagnosis rate in schizophrenic patients was only 1.2 times greater than for other patients. In light of previous studies, she said, she would have expected it to be higher.

What this says to psychiatrists, Dr. Weber noted, "is to look for comorbidity."

She also pointed out that schizophrenic patients had more diagnoses that were not well specified with the ICD-9 codes, which Dr. Weber said is understandable: "When a person is in psychosis, they are not going to go into details" about non–life-threatening conditions.

Other Mental Disorders

Also not surprisingly, the data also showed these patients are more likely to have other mental disorders, including personality disorders, affective psychosis, nondependent drug abuse, drug and alcohol dependence, and suicide and self-inflicted injury.

Dr. Weber said she used the data ending in 2003 because it was the last year for which the data have been adjusted for changes in ICD-9 codes and made homogeneous.

The research also showed demographic differences in the discharges of schizophrenic patients. Overall, 1% of hospital discharges had a schizophrenia diagnosis, but the rate was 1.3% for males and 0.8% for females.

The schizophrenia diagnosis rate was twice as high for discharges of black patients,at 1.8%, compared with white patients, at 0.9%. For people of other races, the rate was 1.0%.

Discharges in the Northern region of the country were almost twice as likely to have a schizophrenia diagnosis, at 1.5%, as those in the South and the West, at 0.8%. For the Midwest, the rate was 1%.

Another part of the study found a significant increase over time in the diagnoses for paranoid, schizoaffective, and not-otherwise-specified schizophrenia. For example, in 1991 a little more than 1.2% of discharges for male patients had a schizophrenia diagnosis. By 2003, it was almost 2%.

The authors also looked back 24 years and found that although overall US hospital length of stay has decreased, it is still twice as high for schizophrenia patients, at 12.5 days in 2003, as for other patients.

The study was funded by the Stanley Medical Research Institute of Bethesda, Maryland, and the Department of the Army. The authors report no conflicts of interest.

American Psychiatric Association: Abstract NR4-073. Presented May 5, 2008.


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