Low-grade inflammation has direct link to bone health
MedWire News: Serum levels of C-reactive protein (CRP) are inversely and independently associated with bone mineral density (BMD) in the general US population, research reveals.
The intriguing finding implies that CRP is directly linked with the risk for fracture, which could have major clinical and public-health implications, say Paola de Pablo (University of Birmingham, UK) and fellow authors.
The team obtained data from the National Health and Nutrition and Examination Survey 1999-2004, a cross-sectional survey of a representative sample of the civilian US population.
In all, 10,475 men and women aged 20 years and older were included. The majority were Caucasian (53%) while Mexican Americans and African Americans each accounted for one-fifth of the total; just over half the participants were female, of whom 47% were postmenopausal.
Among both men and women, there was a significant dose-dependent inverse association between CRP quintiles and total-body BMD, de Pablo et al report in Arthritis & Rheumatism.
In women, mean total-body BMD was 1.089 g/cm2 for those in the bottom quintile of serum CRP versus 1.071 g/cm2 for those in the top quintile, a trend that was statistically significant after adjustment for multiple variables (age, race/ethnicity, poverty income ratio, smoking, alcohol intake, physical activity, body mass index, glomerular filtration rate, menopause, and hormone use).
In men, the total-body BMD values in the bottom and top quintiles of CRP were 1.186 versus 1.167 g/cm2, which was also a statistically significant difference in adjusted analyses.
In both men and women, there was a significant, inverse dose-dependent association between CRP quintiles and BMD at the extremities. Also, in women but not men, there was a significant, inverse dose-dependent association between CRP quintiles and BMD at the lumbar spine.
There was no interaction between CRP and menopause, age, race/ethnicity, and smoking; further adjusting for comorbities, medication use, and vitamin D levels failed to weaken the associations, and results were unchanged if people taking bisphosphonates were excluded.
"Our results indicate that in the general US population, differences in total-body BMD between extreme quintiles of CRP are 2-3%," de Pable and co-authors conclude.
"If these results are confirmed in longitudinal studies, strategies to modify systemic inflammation should be tested to see whether they modify the long term risk of bone loss."
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By Joanna Lyford