Background: It is unclear how early cognitive impairment affects future care needs. Furthermore, the Mini-Mental State Examination (MMSE), a commonly used screening tool in the clinical setting, tends to have a ceiling effect for early cognitive decline. One of the earliest changes in cognitive function is executive impairment. We examined the relationship between executive function, measured with a clock drawing protocol (CLOX1) designed to capture executive impairment, and incident need for increased level of care and total mortality.
Methods: Residents (n = 230) in independent living at a continuing care retirement community were followed for incident need for 24-hour care (mean 2.5 years). Baseline assessment included health status and physical and cognitive function. Time to event analysis was performed to determine the association of the CLOX1 score with the outcomes.
Results: Forty percent of residents had a CLOX1 score <12, and 10% had an MMSE score <26. The event rate for a CLOX1 score <12 was 30 per 100 person-years (p-y) and 13 per 100 p-y for a score > or =12. Similarly, the event rate was 34 per 100 p-y versus 17 per 100 p-y for MMSE <26 and MMSE > or =26, respectively. A CLOX1 score <12 was associated with a twofold higher risk of incident use of 24-hour care (hazard ratio 2.2; 95% confidence interval: 1.5-3.4) and death (hazard ratio 2.3; 95% confidence interval: 1.1-4.8) even after controlling for age, sex, comorbidity, and MMSE scores. The MMSE score was not an independent predictor of incident use of 24-hour care or mortality.
Conclusion: The clock drawing test, scored for executive impairment, but not the MMSE, predicted incident use of 24-hour care and mortality in this cohort of independent older adults.