Cognitive Impairment:An Independent Predictor of Excess Mortality

SACHS, CARTER, HOLTZ, ET AL. ANN INTERN MED, SEP, 2011;155:300-308

ZACHARY LAPAQUETTEPHARMD CANDIDATE

UNIVERSITY OF GEORGIA

Previous studies

Increased risk for mortality in patients formally diagnosed with Alzheimer disease

Adjusted HR for mortality for Alzheimer disease has ranged from 1.40 to 2.84 (3-6 yr)

Recent trials in UK have seen higher mortality in cognitive impairment or dementia

Trials relied on diagnosis of dementia in medical record or limited, self-reported information on co-morbid conditions

Study design

Cohort trial

Safety-net health system

Over age 60

Study design

Single administration of Short Portable Mental Status Questionnaire (SPMSQ)

Patients were placed in 3 study arms

No cognitive impairment (0-2 incorrect responses)

Mild cognitive impairment (3-4)

Moderate to severe cognitive impairment (5+)

Demographic results

Results Level of Cognitive Impairment

Median Survival Time (months)

None 138

Mild 106

Moderate to Severe

63

Results Level of Cognitive Impairment

Median Survival Time (months)

None 138

Mild 106

Moderate to Severe

63

Results

Cox proportional hazards analysis measured hazard ratios of many patient characteristics:

Sex, age, race, education, <90% IBW, diabetes, CHF, cerebrovascular disease, anemia, h/o smoking, cancer, COPD, problem drinking, albumin level <35g/L, atherosclerotic vascular disease, CAD, depression, HTN, cholesterol level >5.2mmol/L, arthritis

Mild impairment HR 1.184 (CI, 1.051 - 1.334)

Mod to severe HR 1.447 (CI, 1.235 - 1.695)

Results

Cox proportional hazards analysis was repeated to match mild and moderate to severe impairment to patients with no impairment and certain variables did not decrease association with mortality

Age, race, sex, education, diabetes, heart disease, and smoking status

Conclusion

Cognitive impairment, as determined by a single screening assessment with the SPMSQ, was associated with an increase in long-term mortality in adults aged 60 and older.

Moderate to severe impairment has striking effect on life expectancy.

Authors’ comment

Results has similar conclusion to recent studies, but this study was able to detect risk of mortality with 1-time assessment of cognition

Mechanism of increased mortality is poorly understood (Consider: safety issues, medication noncompliance)

Presenter’s discussion

Study limited to patients with low socioeconomic status in one community, but had similar results as other recent studies

Criticism of study:

Absent data

Cohort study

Effect of cognitive impairment on cause of death unknown

Overall strong study with wide-ranging implications