Physical activity modifies cognitive impairment-associated mortality risks among chronic kidney disease.

BACKGROUND

Older chronic kidney disease (CKD) patients frequently face unrecognized cognitive impairment and excess mortality. Physical activity (PA) reduces cognitive decline but whether PA modifies cognitive impairment-associated mortality remains unknown.

METHODS

From 2005 to 2011, 30,561 older Taiwanese CKD patients were enrolled. Patients were divided into intact cognition (≥8 scores), mild (6-7 scores), and severe (≤5 scores) cognitive impairment groups by the Short Portable Mental Status Questionnaire (SPMSQ), and were also categorized into high-PA (≥60 min/week of moderate-intensity PA), low-PA (20-60 min/week) or inactive (<20 min/week) groups. Cox regression was conducted to evaluate the individual and joint associations of cognitive impairment and PA on all-cause and cardiovascular mortality.

RESULTS

After a median follow-up of 4.52 years, the all-cause mortality were higher in CKD patients with severe (multivariable-adjusted hazard ratio [aHR] 2.31; 95% confidence interval [CI] 2.05-2.60) and mild (aHR 1.74; CI 1.51-1.99) cognitive impairment than cognitively intact ones. Remarkably, decreased PA amount interacted and amplified the cognitive impairment-associated mortality risks. Notably, the high-PA status linked to lower overall mortality risks both in mild (aHR 0.65; CI 0.45-0.93) and severe (aHR 0.73; CI 0.54-0.99) cognitively-impaired patients as compared to inactivity. Survival tree analysis indicated the least mortality in those with high PA and >8 SPMSQ scores. Similar associations were found in the cardiovascular mortality.

LIMITATIONS

Residual confounding and single ethnicity.

CONCLUSIONS

Cognitive impairment defined by SPMSQ was progressively associated with higher mortality among elderly CKD. Higher PA linked to lower cognitive impairment-associated death risks, and could be promoted for longevity benefits.