C-reactive protein, vitamin D deficiency, and slow gait speed.
OBJECTIVE
To evaluate the independent and joint effects of C-reactive protein (CRP) and 25-OH vitamin D (25(OH)D) levels on mobility disability in older persons.


METHODS
U.S. population-based cross-sectional study.


METHODS
National Health and Nutrition Examination Surveys (2001-2002).


METHODS
Individuals aged 50 and older (N = 1,826).


METHODS
C-reactive protein (mg/dL), with high CRP defined as ≥ 0.2 mg/dL, and 25(OH)D levels (ng/mL) operationalized as severe deficiency (<10 ng/mL), deficiency (10-19.9 ng/mL), insufficiency (20-29.9 ng/mL), and normal (≥ 30 ng/mL). Mobility disability was operationalized as gait speed of <0.8 m/s while completing a 20-foot walk (6.1 m).


RESULTS
High CRP and low 25(OH)D levels were associated with slow gait speed. Individuals with high CRP levels and severe vitamin D deficiency were more likely to have slow gait speed than were those with neither risk factor (odds ratio = 3.54, 95% confidence interval = 1.42-8.84, P = .007). A significant positive association between vitamin D level and gait speed was found only in those with high CRP in stratified analyses. Whites and blacks showed similar findings as the overall population.


CONCLUSIONS
These findings provide evidence of a potential joint effect of vitamin D and CRP on gait speed, suggesting that evaluation and correction of vitamin D levels may be especially important in individuals with high CRP levels.
University of Connecticut Center on Aging, University of Connecticut Health Center, Farmington, Connecticut.
Jatupol
J
Kositsawat
Lisa C
LC
Barry
George A
GA
Kuchel
D000368:Aged; D000369:Aged, 80 and over; D002097:C-Reactive Protein / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D005684:Gait; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000503:physiopathology; D016138:Walking / Q000502:physiology*
D014807:Vitamin D; D002097:C-Reactive Protein
C-reactive protein; gait speed; vitamin D