Global biomarkers of oxidative stress and fractures: a matched case-control study

Abstract

BackgroundEvidence for a relationship between oxidative stress and osteoporotic fractures in humans is limited. Fluorescent oxidation products (FlOPs, excitation/emission wavelengths 320/420nm denoted FlOP_320; 360/420nm [FlOP_360]; and 400/475nm [FlOP_400]) are global biomarkers of oxidative stress, and reflect oxidative damage to proteins, phospholipids, and nucleic acids. We investigated the association between FlOPs and a recent osteoporotic fracture.MethodsWe conducted a case-control study in a Chinese population aged 50 years or older. A recent osteoporotic fracture in the cases was confirmed by x-ray. Cases were matched with community-based non-fracture controls (1:2 ratio) for age (± 4 years) and sex. In addition, we conducted a sensitivity unmatched case-control study which included all fracture cases and all eligible non-fracture controls prior to matching. Plasma FlOPs were measured with a fluorescent microplate reader. We used unconditional logistic regression to analyze the association between FlOPs (per 1-SD increase in logarithmic scale) and fracture; odds ratios (OR) and 95% confidence intervals (95% CI) were reported.ResultsForty-four cases and 88 matched controls (mean age: 68.2 years) were included. After covariate adjustment (i.e., body mass index, physical activity, and smoking), higher FlOP_360 (OR = 1.85; 95% CI = 1.03 – 3.34) and FlOP_400 (OR = 13.29; 95% CI = 3.48 – 50.69) levels, but not FlOP_320 (OR = 0.56; 95% CI = 0.27 – 1.15), were associated with increased fracture risk. Subgroup analyses by fracture site and unmatched case-control study found comparable associations of FlOP_360 and FlOP_400 with hip and non-hip fractures.ConclusionsHigher FlOP_360 and FlOP_400 levels were associated with increased risk of fracture, and this association was comparable for hip and non-hip fractures. Prospective studies are warranted to confirm this finding.

Association between amino acids and recent osteoporotic fracture: a matched incident case-control study

“…Consistent with a previous study ( 16 ), we included the following covariates in this study: demographics (sex and age), lifestyle factors (e.g., physical activity, smoking status, milk intake >1 time/week and calcium supplement), postmenopausal status in females, disease history (e.g., coronary heart disease, type 2 diabetes, stroke), height loss of more than 3 cm after age 40 years, falls from standing height or less within the last 12 months, family history of osteoporosis and fractures, and body mass index (BMI). These factors were included because they were major risk factors for fractures ( 17 , 18 ).…”

“…Similar to our previous study ( 16 ), incident cases were confirmed to be new fractures in the Second Hospital of Jilin University in 2020. Using the survivor sampling methods, we selected controls from a community-based generally healthy population who had no history of fracture in Changchun, Jilin in 2020.…”

“…As compared with controls, cases had significantly lower physical activity and milk intake >1 time/week, and a higher prevalence of falls; other characteristics including age, sex, BMI, smoking, calcium supplement, history of coronary heart disease, type 2 diabetes and stroke, height loss >3 cm, family history of osteoporosis and fractures, were not significantly different between cases and controls. All descriptive data by fracture status have been published ( 16 ).…”

“…The blood collection method was described in a previous study ( 16 ). For cases, we collected blood samples within 2 days after hospitalization for fracture, but before any treatment (i.e., fracture fixation, hip replacement and medications).…”