Social isolation in chronic kidney disease and the role of mobility limitation

Background: Chronic kidney disease (CKD) is associated with multiple comorbidities, hospitalizations and mortality. In older adults, social isolation and poor mobility contribute to these outcomes. We tested the hypothesis that a glomerular filtration rate (GFR) <45 mL/min/1.73 m(2) (CKD Stages 3b-5) is associated with social isolation and that mobility limitation is a key driver of social isolation in patients with CKD. Methods: Data from 9119 participants, ages 57-107 years, from the 2016 wave of the Health and Retirement Studys Venous Blood Study were used for this cross-sectional analysis. Kidney function measured by estimated GFR (eGFR) was the predictor and patients were classified as CKD Stages 3b-5 or non-CKD Stages 3b-5 (eGFR <= 45 or >45 mL/min/1.73 m(2)). The outcomes tested were mobility limitation assessed by self-report and social contact and participation measures assessed by the Psychosocial Life Questionnaire. The associations among kidney function, mobility and social isolation were examined with logistic and ordinary least squares regression, adjusted for covariates and testing for interaction with gender. Results: Participants with CKD Stages 3b-5 (N = 999) compared with non-CKD Stages 3b-5 were older (74.9 versus 68.2 years, P < 0.001) and fewer were female (15% versus 58%, P < 0.001). CKD Stages 3b-5 were associated with higher odds of difficulty walking several blocks [odds ratio 1.44 (95% confidence interval 1.16-1.78)]. Participants with CKD Stages 3b-5 had reduced social contact and social participation (B = -0.23, P < 0.05; B = -0.62, P < 0.05, respectively). Women with CKD Stages 3b-5 were 2.7 times more likely to report difficulty walking several blocks than men with CKD Stages 3b-5, but social isolation in CKD Stages 3b-5 did not vary by gender. In CKD Stages 3b-5 patients, mobility limitation was a risk factor for reduced social contact and participation but did not explain the poor social contact and participation. Conclusion: CKD Stages 3b-5 was associated with both mobility limitation and social isolation in a population-based study of older adults. In contrast to older adults without CKD Stages 3b-5, mobility limitation did not explain the lack of social contact and poor social participation, suggesting other factors are more important.