Influence of cognitive impairment on mortality, complications and functional outcome after hip fracture: Dementia as a risk factor for sepsis and urinary infection

Abstract

Purpose: To analyze the relation between cognitive impairment on arrival at hospital in patients older than 65 years with a hip fracture, and their mortality, medical and surgical complications, and functional outcomes.

Patients and methods: Observational study of a single-center prospective consecutive cohort of 955 patients older than 64 years diagnosed of hip fracture from December/2012 to December/2015. Average age was 86±7.2 (65-104) years and 725 (75.9%) were female. Fractures were extracapsular in 538 cases (56.3%) and intracapsular in 417 (43.7%). Patients were controlled clinically and radiographically in outpatient clinic after 1, 3, 6, and 12 months. Data about basal cognitive status, walking ability before the fracture, medical and surgical complications, functional outcomes and mortality were collected for the year following the fracture.

Statistical analysis: Bivariate analysis (Pearson, Fisher, Mann-Whitney, Wilcoxon) was applied to study statistically significant relations, and contingence coefficients (CC) were calculated.

Results: Patients with cognitive impairment showed a higher overall mortality, (p = 0,000; CC=0,197) even after hospital discharge (p = 0.000; CC=0.198). Similarly, patients with dementia presented a higher rate of respiratory infections (p = 0,029; CC=0,093), urinary tract infections (p = 0,008; CC=0,108) and sepsis (p = 0,011; CC=0,105). On the contrary, we found no correlations between mental status and surgical complications, even for prosthesis dislocation (p = 0.136). Patients with dementia started from poorer functional situations (p = 0,000; CC=0,367) and ended follow-up with lower walking ability (p = 0,000; CC=0,43), but cognitive impairment did not relate statistically with a worse functional recovery (p = 0,304): that is, the proportion of patients who maintained their previous ability to walk was similar in both groups, those with altered mental status and those without it.

Conclusions: Cognitive impairment is a risk factor for mortality in patients with a hip fracture. It is also a risk factor for suffering respiratory and urinary tract infection and sepsis. These two late risks factors have not been published previously. Functional recovery is not conditioned by cognitive impairment, although further studies need to be developed to evaluate the actual role of cognitive impairment on postoperative progression of patients.

Keywords: Cognitive impairment; Dementia; Functional outcome; Hip fracture; Medical complications; Mortality; Surgical complications; Walking ability.