No association between iron status and self-reported health-related quality of life in 16,375 Danish blood donors: results from the Danish Blood Donor Study.

BACKGROUND: Health-related quality of life (HRQL) represents people's subjective assessment of their mental and physical well-being. HRQL is highly predictive of future health. The effect of iron deficiency without anemia induced by blood donation on HRQL is presently unknown. The aim was to explore the relationship between iron status and self-reported mental component score (MCS; SF-12) and physical component score (PCS; SF-12) in Danish blood donors. STUDY DESIGN AND METHODS: Complete relevant data, including the 12-item short-form health survey (SF-12), plasma ferritin levels, age, body mass index, smoking status, C-reactive protein levels, number of donations in the previous 3 years, and PCS and MCS, were available for 8692 men and 7683 women enrolled from March 1, 2010, to December 31, 2010. Multivariable linear and logistic (cutoff at the 10th percentile) regression analyses were used to assess the relationship between iron deficiency (ferritin < 15 ng/mL) and MCS and PCS, respectively. Analyses were performed separately for men and women. RESULTS: There was no significant relationship between iron deficiency and self-reported mental or physical health. CONCLUSION: This study found no association between iron stores and self-reported HRQL among Danish blood donors.

Predictors of hemoglobin in Danish blood donors: results from the Danish Blood Donor Study.

BACKGROUND: It is well known that blood donors are at increased risk of iron deficiency and subsequent development of iron deficiency anemia. We aimed to investigate the effect of factors influencing hemoglobin (Hb) levels. STUDY DESIGN AND METHODS: Initiated in 2010, the Danish Blood Donor Study is a population-based study and biobank. We performed multivariable linear regression analysis to assess the effects of donation activity, physiologic and lifestyle factors, and diet on Hb levels among 15,197 donors. We also performed multivariable logistic regression to evaluate the effects of these factors on the risk of having low Hb (defined as Hb below the 10th percentile among men and women, respectively) and of a decrease in Hb greater than 0.5 mmol/L (0.8 g/dL) between successive donations. All analyses were performed stratified for sex and smoking status. We also tested a previously used model for the prediction of Hb. RESULTS: The strongest predictors of Hb and risk of low Hb were low ferritin (<15 ng/mL) and current use of iron supplementation (yes/no). No dietary factors were found to be consistently significant in multivariable models predicting Hb levels, risk of having low Hb, or risk of a decrease in Hb greater than 0.5 mmol/L. We found similar effects to previous studies of factors in the predictive model, with little additional effect of including smoking status and ferritin. CONCLUSIONS: As ferritin was the strongest predictor of Hb, this study supports the implementation of regular ferritin measurement as a method of risk assessment among blood donors.

No association between rs6897932 in the gene encoding interleukin-7 receptor α and low-grade inflammation or self-reported health - results from the Danish Blood Donor Study.

The T-allele in the single nucleotide polymorphism rs6897932 in the gene encoding the IL-7 receptor α (IL7RA) is associated with reduced risk of autoimmune diseases including multiple sclerosis and also affects the course of HIV infection. Low-grade inflammation (LGI) and self-reported, health-related quality of life (HRQL) are often associated with chronic diseases and widely used in assessing and monitoring health status. The aim of the present study was to evaluate whether the T-allele in rs6897932 is associated with reduced risk of LGI (hsCRP 3-10 mg/L), history of infectious mononucleosis (IM), and HRQL in healthy individuals. A total of 17, 293 healthy Danish individuals from the Danish Blood Donor Study were included in the analyses. We tested rs6897932 as a predictor of LGI, self-reported IM, and HRQL in univariable and multivariable models stratified by sex. No associations between rs6897932 and LGI, self-reported IM or HRQL were found in men or women. This suggests that rs6897932 is not associated with general inflammation, and the reported associations between the T-allele in rs6897932 with several autoimmune diseases may be mediated through effects on a restricted part of the immune system.

The impact of CCR5-Δ32 deletion on C-reactive protein levels and cardiovascular disease: Results from the Danish Blood Donor Study.

BACKGROUND AND PURPOSE: The C-C chemokine receptor 5-Δ32 deletion (CCR5-Δ32) has been associated with lower levels of C-reactive protein (CRP), but the effect on cardiovascular diseases is uncertain. This study addresses the impact of CCR5-Δ32 on the risk of low-grade inflammation and hospitalization with cardiovascular diseases in a large cohort of blood donors. METHODS: Genotyping of 15,206 healthy participants from The Danish Blood Donor Study for CCR5-Δ32 was performed and combined with CRP measurements and questionnaire data. Cardiovascular disease diagnoses were identified by ICD-10 codes in the Danish National Patient Registry. RESULTS: CCR5-Δ32-carriers had a higher risk of hospitalization for cardiovascular diseases when compared with wild-type homozygotes (hazard ratio = 1.35, 95%-confidence interval: 1.00-1.87). CRP levels were unaffected by the CCR5-Δ32 deletion. CONCLUSION: In this cohort, carriers of the CCR5-Δ32 deletion had normal CRP levels but a borderline significant increased risk of cardiovascular diseases.

Combined oral contraception and obesity are strong predictors of low-grade inflammation in healthy individuals: results from the Danish Blood Donor Study (DBDS).

BACKGROUND: C-reactive protein (CRP) is a well-established marker of inflammation. The level of CRP is affected by several lifestyle factors. A slightly increased CRP level, also known as low-grade inflammation (LGI), is associated with increased risk of several diseases, especially cardiovascular disease. The aim of this study was to identify predictors of increased CRP levels in healthy individuals. We therefore assessed CRP in a large cohort of blood donors. METHODS: We measured plasma CRP levels in 15,684 participants from the Danish Blood Donor Study. CRP was measured by a commercial assay. Furthermore, all participants completed a standard questionnaire on smoking status, alcohol consumption, physical activity, diet, and various body measurements. Female participants also reported the use of contraception, childbirth, and menopausal status. The relationship between LGI (defined here as a plasma CRP level between 3 mg/L and 10 mg/L) and predictors was explored by multivariable logistic regression analysis. Results were presented as odds ratios (OR) with 95% confidence intervals (CI). RESULTS: We found LGI in a total of 1,561 (10.0%) participants. LGI was more frequent in women using combined oral contraception (OC) (29.9%) than in men (6.1%) and women not using OC (7.9%). Among premenopausal women, OC was the strongest predictor of LGI (odds ratio = 8.98, p<0.001). Additionally, body mass index (BMI) and waist circumference were positively associated with LGI. CONCLUSION: High BMI and abdominal obesity strongly predicted LGI among healthy individuals. However, the most striking finding was the high prevalence of LGI among premenopausal women who used combined oral contraception. Although the significance of CRP as a marker of inflammation is well known, the role of CRP in pathogenesis is still uncertain. The impact of oral contraception on CRP levels should nevertheless be considered when CRP is used in risk assessment.