The Impact of Delirium Screening on Admission to General Hospital Using Stanford Proxy Test for Delirium SPTD [1]® , A Quality Improvement Project

Reliability and Validity of the Spanish Adaptation of the Stanford Proxy Test for Delirium in Two Clinical Spanish-Speaking Communities

BACKGROUND

Delirium is the most prevalent neuropsychiatric syndrome experienced by patients admitted to inpatient clinical units, occurring in at least 20% of medically hospitalized patients and up to 85% of those admitted to critical care units. Although current guidelines recommend the implementation of universal prevention strategies, the use of management strategies largely depends on constant surveillance and screening. This allows for the timely diagnosis and correction of its underlying causes and implementation of management strategies.

OBJECTIVE

It was to adapt and analyze the Spanish adaptation of the Stanford Proxy Test for Delirium (S-PTDsv) instrument for its use among Spanish-speaking populations. The S-PTD is an instrument consisting of 13 observational items to be completed by a clinician observer, usually the patient's nurse. The completion of the questionnaire takes about 1 minute and does not require the active participation of the person evaluated, which has important clinical advantages compared to other available instruments (e.g., the Confusion Assessment Method).

METHODS

The psychometric properties of the S-PTDsv were evaluated in a population of 123 patients using a quantitative, cross-sectional design. All subjects were over 18 years of age and hospitalized in various inpatient medico-surgical and intensive care unit services, either at the Barcelona Clinical Hospital (Barcelona, Spain) or the UC-Christus Health Network Clinical Hospital (Santiago, Chile, S.A.). The ultimate diagnosis of delirium was made by a member of the Psychiatry Consult Service by means of an independent neuropsychiatric evaluation based on the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria, published in 2013, which is the latest version of the diagnostic manual. All study tests were performed by study personnel who were blinded to each other's test results within an hour of each other.

RESULTS

In the receiver operator characteristic (ROC) curve analysis, the S-PTDsv demonstrated excellent classification qualities when compared with the DSM-5 as the classification reference standard. Using a cutoff point of ≥3, the S-PTDsv had a sensitivity of 94% and a specificity of 97%. The area under the curve indicator was equal to 0.95, suggesting the S-PTDsv has an excellent overall performance in accurately identifying cases of delirium. Accordingly, the S-PTDsv's positive predictive value = 0.93, and the negative predictive value = 0.97. The internal reliability measured with Cronbach's alpha was 0.96. Confirmatory factor analysis revealed a 1-dimensional structure with high loadings (>0.72), demonstrating that all items similarly contribute to the total diagnostic dimension, suggesting adequate construct validity. This provided evidence of convergent validity.

CONCLUSIONS

The performance of the S-PTDsv, as compared to a blinded neuropsychiatric assessment based on DSM-5, indicates that it is an effective instrument for the detection of delirium, in the Spanish-speaking populations. These results are comparable and consistent with previously published studies in the English language version.

Validation of the Stanford Proxy Test for Delirium (S-PTD) among critical and noncritical patients

BACKGROUND

The Stanford Proxy Test for Delirium (S-PTD) is a tool developed to be completed by nurses at the end of their shift. It was designed to use the knowledge acquired during a full shift of nurse-patient interaction. The objective of our study was to validate the S-PTD among a mixed sample of patients in both the intensive care unit (ICU) and non-ICU settings.

METHODS

A cross-sectional study was conducted in an ICU and three general medical wards in a tertiary care hospital. Patients were independently and blindly assessed for delirium by (1) the patients' primary nurses using the S-PTD at the end of their shift, and (2) a Consultation liaison psychiatrist who conducted a neuropsychiatric evaluation based on the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

RESULTS

A total 288 patients were included in current analysis. Using the S-PTD, delirium was identified in 72 (25.0%), while an expert neuropsychiatric examination, based on DSM-5 identified delirium in 75 (26.0%) patients. This study demonstrated that the S-PTD has very strong discriminative ability (area under the curve= 0.946, p<0.001). An S-PTD cut-off score ≥3 was associated with an 82.7% sensitivity, an 95.3% specificity, an 86.1% positive predictive value, a 94.0% negative predictive value, and a 92.0% overall diagnostic accuracy. These results were similar in both ICU and general ward patients.

CONCLUSION

The S-PTD has excellent sensitivity and specificity in detecting delirium in both ICU and ward patients, even when compared with the gold-standard, a DSM-based neuropsychiatric examination.