THE MINI-COG: COGNITIVE IMPAIRMENT AND SURGICAL OUTCOME

the anesthesia consultant

Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group
Richard Novak, MD is a Stanford physician board-certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
email rjnov@yahoo.com
phone 650-465-5997

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What is a Mini-Cog? Most anesthesia professionals have never heard of the Mini-Cog test, but recent evidence shows it can provide important prognostic information on our geriatric patients prior to surgery.

 

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The Mini-Cog™ (© S. Borson, All rights reserved) is a 3-minute screening test for cognitive impairment. The test consists of three steps: Step 1 is Three Word Registration, Step 2 is Clock Drawing, and Step 3 is Three Word Recall Scoring.

STEP 1 (Three Word Registration): To administer the test, you look directly at a patient and say, “Please listen carefully. I am going to say three words that I want you to repeat back to me now and try to remember. The three words are [select one of the list of three words from the versions below]. Please say them for me now.”

If the patient is unable to repeat the words after three attempts, you move on to Step 2.

Version 1: Banana Sunrise Chair

Version 2: Leader Season Table

Version 3: Village Kitchen Baby

Version 4: River Nation Finger

Version 5: Captain Garden Picture

Version 6: Daughter Heaven Mountain

STEP 2 (Clock Drawing): You say: “Next, I want you to draw a clock for me. First, put in all of the numbers where they go.” When that is completed, say: “Now, set the hands to 10 past 11.” You utilize a preprinted circle on a blank page for this exercise. You move to Step 3 if the clock is not complete within three minutes.

STEP 3 (Three Word Recall Scoring): You ask the person to recall the three words you stated in Step 1.

SCORING: Word Recall= ______ (0-3 points), 1 point for each word spontaneously recalled without cueing. Clock Draw= ______ (0 or 2 points). Normal clock = 2 points. A normal clock will have all numbers placed in the correct sequence and approximately correct position (12, 3, 6 and 9 are in anchor positions) with no missing or duplicate numbers. The clock hands are pointing to the 11 and 2 (11:10) positions. Hand length is not scored. Inability or refusal to draw a clock = 0 points.

TOTAL SCORE = Word Recall score + Clock Draw score. Some studies consider a score of 3 or less diagnostic of cognitive impairment, other studies require a score of 2 or less.

 

In the November 2017 issue of Anesthesiology, Culley et al of Harvard utilized the Mini-Cog as a preoperative screening test on 211 patients without a diagnosis of dementia, 65 years of age or older, who were scheduled for an elective total hip or knee replacement. Fifty of 211 (24%) of the patients screened positive for probable cognitive impairment (CI) by a Mini-Cog score of 2 or less. Compared to patients with a score of 3 or greater, the low Mini-Cog scorers were more likely to be discharged to a place other than home (67% vs. 34%), develop postoperative delirium (21% vs. 7%), and have a longer hospital length of stay. Culley concluded that many older elective orthopedic surgical patients have probable cognitive impairment preoperatively, and that this impairment is associated with the development of postoperative complications. The authors suggest that identifying these patients who are at greater risk may allow for the design of interventions to lower complications in this population.

Cognitive impairment (CI) is not dementia, but in all likelihood is a precursor. How common is CI, or the related diagnosis “cognitive impairment, not dementia” (CIND) in America? The incidence of both is higher than you might guess. Plassman et al evaluated for CI in participants in the Aging, Demographic, and Memory Study using a comprehensive in-home assessment. A total of 456 individuals aged 72 years and older who were not demented at baseline were followed for 8 years. An expert panel assigned the diagnosis of normal cognition, CIND, or dementia. The incidence of dementia was 33.3 per 1,000 person-years. The incidence of CIND was 60.4 per 1,000 person-years. An estimated 120.3 individuals per 1,000 person-years progressed from CIND to dementia. Over a 5.9-year period, 3.4 million individuals aged 72 and older in the United States developed dementia, and over this same period almost 4.8 million individuals developed incident CIND. Their conclusions: the incidence of CIND is greater than the incidence of dementia, and that patients with CIND are at a high risk of progressing to dementia.

The value of the Mini-Cog test has been studied in other populations of geriatric patients. Robinson et al studied the preoperative Mini-Cog test in subjects 65 years of age and older, prior to a planned elective operation requiring a postoperative ICU admission. In this study, CI was defined as a Mini-Cog score of 3 or less. Eighty-two out of 186 subjects (44%) had baseline impaired cognition. Compared to those who scored 4 or greater, the CI group had a higher incidence of postoperative complications (41% vs. 24%), a higher incidence of delirium (78% vs. 37%), longer hospital stays (15 ± 14 vs. 9 ± 9 days), higher rate of discharge to an institution (42% vs. 18%), and a higher 6-month mortality rate (13% vs. 5%).

Patel et al studied the Mini-Cog test on 720 consecutive patients prior to discharge during hospitalization for heart failure. A Mini-Cog score of 2 or less was considered abnormal. The prevalence of CI was high (23%). In the 6 months following hospitalization, 342 of the 72 patients (48%) were readmitted, and 24 (3%) died. A poor Mini-Cog performance was identified as the most important predictor of readmission or death among 55 variables studied.

At Stanford our department is titled the Department of Anesthesiology, Perioperative and Pain Medicine. Perioperative medicine includes preoperative evaluation. The concept of a Preoperative Anesthesia Clinic originated with Dr. Steve Fischer at Stanford. As a double-boarded anesthesiologist and internal medicine doctor, I’ve honed my skills in the preoperative evaluation of the geriatric patient. Up to the present I have not utilized the Mini-Cog test in my preoperative evaluation.

Should the future preoperative evaluation of geriatric surgical patients include a Mini-Cog test?

Perhaps.

The American College of Surgeons and the American Geriatrics Society recently published guidelines recommending the preoperative screening of older surgical patients with a tool such as the Mini-Cog. These are recommendations, not mandates, and time will tell how prevalent the Mini-Cog becomes in the geriatric anesthesia preoperative workup. It’s unlikely that patients will be denied surgery for borderline or low preoperative Mini-Cog scores, but the potential for improving postoperative outcomes in the low scorers presents a challenge for the entire perioperative community of anesthesiologists, surgeons, intensivists, and nurses.

Keep your eyes open for further research regarding the value of the preoperative Mini-Cog test. And as you age, you might choose to rehearse your retention of the three-word lists above, and practice drawing clocks that read 11:10.   🙂

 

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