Mild to moderate cognitive impairment is a major risk factor for mortality and nursing home admission in the first year after hip fracture

Abstract

Background: It is not well established if and to what extent mild to moderate cognitive impairment predicts mortality and risk of nursing home admission after hip fracture.

Objective: To investigate prospectively whether and to what extent mild to moderate cognitive impairment, contributes to mortality and admission to nursing home in the first year after acute hip fracture.

Methods: We enrolled 173 patients with acute hip fracture age 65 and older who reached a Mini-Mental State Examination (MMSE) score of at least 15 during acute care after hip fracture repair. An MMSE score of 15 to 24 (median) was classified as mild to moderate cognitive impairment. Primary outcomes were mortality in all and admission to nursing home among seniors who lived at home prior to their hip fracture. Follow-up was 12 months with clinical visits at baseline, 6, and 12 months, plus monthly phone calls. We used Cox proportional hazards models controlling for age, sex, body mass index, baseline number of comorbidities and 25-hydroxyvitamin D status, and severe incident infections to assess the risk of mortality and nursing home admission. Because the study population was enrolled in a factorial design clinical trial testing high dose vitamin D and/or an exercise home program, all analyses also controlled for these treatment strategies.

Results: Of 173 acute hip fracture patients enrolled, 79% were women, 77% were admitted from home, and 80% were vitamin D deficient (<20ng/ml). Mean age was 84 years. 54% had mild to moderate cognitive impairment. Over the 12-month follow-up, 20 patients died (27% of 173) and 47 (35% of 134) were newly admitted to a nursing home. Mild to moderate cognitive impairment was associated with a more than 5-fold increased risk of mortality (HR=5.77; 95% CI: 1.55-21.55) and a more than 7-fold increased risk of nursing home admission (HR=7.37; 95% CI: 1.75-30.95). Additional independent risk factors of mortality were male gender (HR=3.55; 95% CI: 1.26-9.97), low BMI (HR=7.25; 95% CI: 1.61-33.74), and baseline 25-hydroxyvitamin D level (per 1ng/ml: HR=0.93; 95% CI: 0.87-0.998; p=0.04).

Conclusions: Mild to moderate cognitive impairment in patients with acute hip fracture is associated with a high risk of mortality and nursing home admission during the first year after hip fracture. Female gender, a greater BMI and a higher 25-hydroxyvitamin D status may protect against mortality after hip fracture independent of cognitive function.

Trial registration: ClinicalTrials.gov NCT00133640.