Megan Brooks

May 25, 2016

ATLANTA — A simple test for delirium that is accurate and quick, is easily administered, and does not require patient participation may provide a more accurate diagnostic tool, new research suggests.

The Stanford Proxy Test for Delirium (S-PTD) relies on nursing staff's observations and may increase early recognition and diagnosis of delirium, investigators say.

In a comparative pilot study, the S-PTD performed "very well" against the Confusion Assessment Method (CAM) in identifying delirium and "equally well with hypoactive and hyperactive delirium," said Jose R. Maldonado, MD, professor of psychiatry, internal medicine, surgery and emergency medicine and law at Stanford University, California, and president-elect of the American Delirium Society.

The findings were presented here at American Psychiatric Association (APA) 2016 Annual Meeting.

Common Problem

The S-PTD is the first diagnostic test for delirium that combines criteria from the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and the International Classification of Diseases, 10th revision (ICD-10). It was developed in close collaboration with nursing staff at Stanford Medical Center.

The S-PTD eliminates the need for direct patient participation in the assessment; instead, nurses complete the tool at the end of their shift, thus using the full-shift patient interaction to gain the information needed to diagnose delirium, Dr Maldonado said.

The pilot study involved 277 patients (mean age, 59.9 years; 54% male) admitted to the neurology and neurosurgical units. They were separately and blindly screened for symptoms of delirium by use of the S-PTD (performed by the patient's nurse), the CAM (performed by a psychosomatic medicine fellow), and a clinical neuropsychiatric evaluation based on DSM-5/ICD-10 criteria (performed by a psychosomatic medicine specialist).

According to a cutoff score of 4 or more, the S-PTD had a sensitivity of 79%, specificity of 91%, positive predictive value of 70%, and negative predictive value of 94%. Performance of the S-PTD was on par with the CAM in identifying delirium, with a McNemar test P value of .739.

The S-PTD took less time for nurses to complete than the CAM. After an initial 2-week training period, it took the average nurse less than 1 minute to complete compared with 5 minutes for the CAM. Nurses also reported that the S-PTD was easier to use, liked it better than the CAM, and were more willing to complete it.

Delirium is common in hospitalized general medical patients and is associated with a range of negative outcomes among medically ill patients, including long-term cognitive impairment. Dr Maldonado noted that "about 40% of patients who develop delirium never go back to baseline in terms of cognitive function. That's a huge number."

Despite several validated tools to screen for delirium in the hospital setting, delirium is misdiagnosed or unrecognized in over half of cases. It is "extremely poorly recognized by physicians," Dr Maldonado said, adding, "available tools are just not that great in the real world."

This may be partly due to their reliance on the patient's report of symptoms or active participation in the delirium screening tool itself. The S-PTD, which relies on the observations of nursing staff, could potentially give a more accurate assessment of patient symptoms and enhance recognition of delirium and appropriate treatment, concluded Dr Maldonado.

Sensitive Enough?

Reached for outside comment, Donna Marie Fick, PhD, RN, distinguished professor, Penn State University College of Nursing, University Park, Pennsylvania, said "having a quick test nurses can do and that nurses played a role in developing is important and nice work."

She cautioned, however, that a sensitivity of 79% for an initial screen is "way too low for a condition like delirium that has a high mortality and poor outcomes. They would be missing over 20% of all cases, so I would be very cautious unless they can improve the sensitivity. Secondly, given the items are not operationalized it is likely to have different results and lower sensitivity in the real-world setting."

Last year, Dr Fick and her colleagues published initial results with an ultra-brief 2-item bedside test for delirium (J Hosp Med. 2015;10:645-650).

"The test takes 36 seconds to administer and has a sensitivity (to pick up true cases of delirium when it is actually present) of 93% and even higher in persons with dementia (96%)," she told Medscape Medical News.

"I believe high sensitivity for the initial screen is crucial and then could be followed by another test with both high sensitivity and specificity if they fail. We are currently testing this in a funded NIH [National Institutes of Health] study," she added.

The study had no commercial funding, and the authors have disclosed no relevant financial relationships.

American Psychiatric Association (APA) 2016 Annual Meeting. SCR-Measurements and Scales, no. 3. Presented May 17, 2016.

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