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Executive dysfunction and depressive symptoms predict post-operative delirium

Executive dysfunction and depressive symptoms predict post-operative delirium

Critique date: Mon, 05/24/2010 - 1:25pm
Institution: 
Mount Sinai School of Medicine
   
Article Citation
Citation: 
Greene NH et al. Measures of Executive Function and Depression Identify Patients at Risk for Postoperative Delirium. Anesthesiology. 2009. 110: 788-95
   
Clinical Bottom Lines
In a small study of 100 adults over age 50, primarily male, executive dysfunction as measured by Trails B test and depressive symtoms as measured by the GDS-SF were independent predictors of postoperative delirium.  Patients were excluded if they underwent cardiac, neurosurgical or carotid procedures.  Global cognitive function as measured by the modified MMSE (3MS) was not found to be a statistically significant predictor of postoperative delirium. 
   
Methods
Type of Study: 
Prognosis
Study Design: 
Cohort study
Follow-up Period: 
3 days postoperative
Setting: 
Academic Hospital and VA Medical Center
Patient Population: 

n=100 patients undergoing major non-cardiac surgery
Mean Age 64.6 +/- 7.7
91% Male
69% White
 

Significant Exclusions: 

Patients were excluded if:
Age <50
Undergoing cardiac, carotid or neurosurgical procedures
Illiterate
Non-English speaking
Unwilling or incapable to give informed consent
Serious visual or hearing deficits precluding neuropsych testing
Patients not returning to the institution for follow up visits
 

Intervention/Exposure: 
Preoperative evaluation performed within 14 days of surgery.  Patient demographics and Charlson CoMorbidity Index obtained as well as American Society of Anesthesiologists physical status classification.  Neuropsych tests administered by trained member of the research team preoperatively:  CAM, Modified MMSE (3MS), Trails Making Test, Digit Symbol Substitution Scores, Symbol Search Subtest of Wechsler Adult Intelligence Scale-III, GDS (15Q), Numerical Rating for Pain.

Patients visited for the first 3 days after surgery and the CAM was administered.  Patients were defined as having delirium if the CAM was positive, and the result was confirmed by a second member of the research team. 
Outcome Measures: 
Primary Outcome: occurance of Delirium in the first 3 days of the postoperative period

Secondary Outcomes:
Duration of Hospitalization
30-day morbidity as defined by National Surgical QI Program outcomes
90 day mortality
Participant Follow-up: 
92% (100 out of 109) of enrolled participants reached primary endpoint. 4 patients withdrew, 4 had cancellation of surgery, 1 did not complete cognitive testing.
   
Conclusion
Results: 
16 of 100 patients developed post-operative delirium
Bivariate analysis found that GDS, Digit Symbol Test, Symbol Search Test were associated with post-operative delirium. 

Multivariate analysis of preoperative factors (including demographics) showed that the GDS and Trails B were independently associated with delirium. 
    GDS:  Odds ratio 1.53  (1.22-2.05)  p=0.0001
    Trails B: Odds ratio: 1.02 (1.01-1.04)  p=0.0007

Combination of these two tests has a specificity of 99% and positive predictive value of 83% for predicting delirium
Concerns Regarding Methodology, Applicability to Older Adults, etc.: 
The study sample consisted of 91% male, limiting the generalizability of the study results to female population.
Small sample size may yield less reliable estimates.
Average age is 64, may not be applicable to geriatric populations.
The study did not include patients who could not provide informed consent, limiting the sample to patients with better cognitive function; inclusion of patients with cognitive impairment using surrogate consent may provide a sample more representative of the geriatric population.
Funding Source and Role: 
None
Created By: 
Allison Margold Ostroff, Second Year Geriatrics Fellow, Mount Sinai Department of Geriatrics
This is a review of the validity of a single study; the ‘bottom lines’ do not reflect comparison with the rest of the literature on this subject.