Association of CKD with disability in the United States

Abstract

Background: Little is known about disability in early-stage chronic kidney disease (CKD).

Study design: Cross-sectional national survey (National Health and Nutrition Examination Survey 1999-2006).

Setting & participants: Community-based survey of 16,011 noninstitutionalized US civilian adults (aged ≥20 years).

Predictor: CKD, categorized as no CKD, stages 1 and 2 (albuminuria and estimated glomerular filtration rate [eGFR] ≥60 mL/min/1.73 m²), and stages 3 and 4 (eGFR, 15-59 mL/min/1.73 m²).

Outcome: Self-reported disability, defined by limitations in working, walking, and cognition and difficulties in activities of daily living (ADL), instrumental ADL, leisure and social activities, lower-extremity mobility, and general physical activity.

Measurements: Albuminuria and eGFR assessed from urine and blood samples; disability, demographics, access to care, and comorbid conditions assessed using a standardized questionnaire.

Results: Age-adjusted prevalence of reported limitations generally was significantly greater with CKD: for example, difficulty with ADL was reported by 17.6%, 24.7%, and 23.9% of older (≥65 years) and 6.8%, 11.9%, and 11.0% of younger (20-64 years) adults with no CKD, stages 1 and 2, and stages 3 and 4, respectively. CKD also was associated with greater reported limitations and difficulty in other activities after age adjustment, including instrumental ADL, leisure and social activities, lower-extremity mobility, and general physical activity. Other demographics, socioeconomic status, and access to care generally only slightly attenuated the observed associations, particularly in older individuals; adjustment for cardiovascular disease, arthritis, and cancer attenuated most associations such that statistical significance no longer was achieved.

Limitations: Inability to establish causality and possible unmeasured confounding.

Conclusion: CKD is associated with a higher prevalence of disability in the United States. Age and other comorbid conditions account for most, but not all, of this association.

Figure 1

A[nd6]ge-adjusted prevalence of disability, as measured by self-report of general limitations (A) or of at least some difficulty in performing at least one activity in a domain (B), by CKD status, NHANES 1999–2006. *P<0.05; **P<0.001 vs. no CKD. ADL, activities of daily living (getting in and out of bed, using fork/knife/cup [eating], dressing oneself); IADL, instrumental activities of daily living (managing money, house chores, preparing meals); LSA, leisure and social activities (going to the movies, attending social event, leisure activity at home); LEM, lower extremity mobility (walking ¼ mile, walking up to 10 steps, stooping/kneeling/crouching, walking between rooms on same floor, standing up from armless chair): GPA, general physical activity (lifting or carrying heavy objects, reaching up overhead, grasping/holding small objects, standing for long periods, sitting for long periods).

Figure 1

A[nd6]ge-adjusted prevalence of disability, as measured by self-report of general limitations (A) or of at least some difficulty in performing at least one activity in a domain (B), by CKD status, NHANES 1999–2006. *P<0.05; **P<0.001 vs. no CKD. ADL, activities of daily living (getting in and out of bed, using fork/knife/cup [eating], dressing oneself); IADL, instrumental activities of daily living (managing money, house chores, preparing meals); LSA, leisure and social activities (going to the movies, attending social event, leisure activity at home); LEM, lower extremity mobility (walking ¼ mile, walking up to 10 steps, stooping/kneeling/crouching, walking between rooms on same floor, standing up from armless chair): GPA, general physical activity (lifting or carrying heavy objects, reaching up overhead, grasping/holding small objects, standing for long periods, sitting for long periods).

Figure 2

Age-, gender- and race/ethnicity-adjusted* prevalence of reported difficulty with activities of daily living (ADL; getting in and out of bed, using fork/knife/cup [eating], dressing oneself) among adults with CKD and other self-reported conditions. CVD, cardiovascular disease. A. Prevalence of reported difficulty with ADL among U.S. adults with various conditions. B. Overlap of CKD with comorbid conditions for reported difficulty with ADL.

Figure 2

Age-, gender- and race/ethnicity-adjusted* prevalence of reported difficulty with activities of daily living (ADL; getting in and out of bed, using fork/knife/cup [eating], dressing oneself) among adults with CKD and other self-reported conditions. CVD, cardiovascular disease. A. Prevalence of reported difficulty with ADL among U.S. adults with various conditions. B. Overlap of CKD with comorbid conditions for reported difficulty with ADL.