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Introduction: Thorough assessment of the antiphospholipid syndrome (APS) includes retesting of positive antiphospholipid antibody (aPL) tests after at least 12 weeks, and a full antiphospholipid antibody profile. To what extent this work‐up is done in clinical practice is unknown. Methods: Data on 25 116 in‐ and out‐hospital patients tested for the presence of lupus anticoagulant (LA), the aPL which most strongly correlates with thrombosis, was extracted from the laboratory information system of the only laboratory that performs LA tests in the Capital Region, Denmark. We estimated fraction of repeated tests, tests repeated within the recommended time span, and fraction with a full aPL profile. Results: Out of 25 116 patients, 843 were positive for LA (3.3%), and 3948 results were inconclusive (16%). Only 51% (95% CI of the proportion: 48%–54%) (n = 431) of positive tests were repeated. The proportion of inconclusive LA test results increased from 13% (12%–15%) in 2009 to 20% (19%–22%) in 2020. Out of the positive tests repeated within the first year, only 60/353 (17%; 13%–21%) were repeated within 12–16 weeks; 177/353 (50%; 45%–55%) were re‐tested within the first 12 weeks of first positive test result. The proportion of patients with a full antiphospholipid antibody profile increased from 161/1978 (8%) in 2010 to 1041/1978 (43%) in 2020. Conclusion: We found several issues with the laboratory workup of APS. This indicates a need for increased awareness of comprehensive laboratory assessment of possible APS as well as a closer collaboration between the laboratory and clinicians. [ABSTRACT FROM AUTHOR]

Aims It is unclear whether higher triglyceride metabolism per se contributes to mortality separate from elevated triglyceride-rich lipoproteins and body mass index. This study tested the hypotheses that higher triglyceride metabolism, measured as higher plasma glycerol and β-hydroxybutyrate, is associated with increased all-cause, cardiovascular, cancer, and other mortality. Methods and results This study included 30 000 individuals nested within 109 751 individuals from the Copenhagen General Population Study. During a median follow-up of 10.7 years, 9897 individuals died (2204 from cardiovascular, 3366 from cancer, and 2745 from other causes), while none were lost to follow-up. In individuals with glycerol >80 µ mol/L (highest fourth) vs. individuals with glycerol <52 µ mol/L (lowest fourth), the multivariable adjusted hazard ratio for all-cause mortality was 1.31 (95% confidence interval 1.22–1.40). In individuals with β-hydroxybutyrate >154 µ mol/L (highest fourth) vs. individuals with β-hydroxybutyrate <91 µ mol/L (lowest fourth), the multivariable adjusted hazard ratio for all-cause mortality was 1.18 (1.11–1.26). Corresponding values for higher plasma glycerol and β-hydroxybutyrate were 1.37 (1.18–1.59) and 1.18 (1.03–1.35) for cardiovascular mortality, 1.24 (1.11–1.39) and 1.16 (1.05–1.29) for cancer mortality, and 1.45 (1.28–1.66) and 1.23 (1.09–1.39) for other mortality, respectively. Results were robust to exclusion of first years of follow-up, to stratification for covariates including plasma triglycerides and body mass index, and to further adjustments. Conclusion This study observed an increased risk of all-cause, cardiovascular, cancer, and other mortality with higher triglyceride metabolism. This was not explained by higher plasma triglycerides and body mass index. The hypothesis studied in the present paper should be further validated by isotope flux studies. [ABSTRACT FROM AUTHOR]

Aims Recent evidence suggest that the lipoprotein(a)-associated risk of atherosclerotic cardiovascular disease (ASCVD) may be observed only in individuals with low-grade systemic inflammation. It was hypothesized that high lipoprotein(a) is a main driver for the risk of ASCVD, myocardial infarction, and aortic valve stenosis irrespective of C-reactive protein levels. Methods and results A total of 68 090 individuals from the Copenhagen General Population Study, a prospective cohort study, were included. During a median follow-up of 8.1 years, 5104 individuals developed ASCVD, 2432 myocardial infarction, and 1220 aortic valve stenosis. The risk of ASCVD, myocardial infarction, and aortic valve stenosis increased with higher values of both lipoprotein(a) and C-reactive protein. For individuals with lipoprotein(a) in the 91st–100th percentiles (≥70 mg/dl, ≥147 nmol/l) vs. the 1st–33rd percentiles (≤6 mg/dl, ≤9 nmol/l), the multivariable-adjusted hazard ratio for ASCVD was 1.61 (95% confidence interval 1.43–1.81) for those with C-reactive protein <2 mg/l and 1.57 (1.36–1.82) for those with C-reactive protein ≥2 mg/l (P for interaction = 0.87). The corresponding values were 2.08 (1.76–2.45) and 1.65 (1.34–2.04) for myocardial infarction, and 2.01 (1.59–2.55) and 1.73 (1.31–2.27) for aortic valve stenosis, respectively (P for interaction = 0.15 and = 0.18). The highest absolute 10-year risks were found in men aged 70–79 years with lipoprotein(a) levels in the 91st–100th percentiles and C-reactive protein ≥2 mg/l, with 34% for ASCVD, 19% for myocardial infarction, and 13% for aortic valve stenosis. The corresponding values in women were 20%, 10%, and 8%, respectively. Conclusion High lipoprotein(a) was a main driver for the risk of ASCVD, myocardial infarction, and aortic valve stenosis independent of C-reactive protein levels. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is observationally associated with a higher risk of nonalcoholic fatty liver disease (NAFLD); however, the causal relationship between the two diseases remains unclear. Objective: We hypothesized that individuals with NAFLD or elevated liver fat content have higher risk of psoriasis and that NAFLD is a causal risk factor for psoriasis. We tested this using a Mendelian randomization approach. Methods: We included 108,835 individuals from the Danish general population, including 1,277 individuals with psoriasis and 802 individuals with NAFLD according to ICD codes. To estimate liver fat content, a subset of the participants (N = 7,416) also had a CT scan performed. First, we tested whether a diagnosis of NAFLD or elevated liver fat content was observationally associated with risk of psoriasis. Subsequently, we used the genetic variants PNPLA3 and TM6SF2, both strongly associated with NAFLD and high liver fat content, to test whether NAFLD was causally associated with increased risk of psoriasis. Results: Observationally, individuals with vs. without a diagnosis of NAFLD had higher risk of psoriasis with an odds ratio of 2.03 (95% confidence interval 1.28- 3.21). The risk of psoriasis increased in a stepwise manner with increasing liver fat content with an odds ratio of 5.00 (2.63-9.46) in individuals in the highest quartile of liver fat content compared to individuals in the lowest quartile. In genetic analyses, PNPLA3 and TM6SF2 were both associated with increased risk of NAFLD but not with increased risk of psoriasis. Conclusion: Observationally, a diagnosis of NAFLD or elevated liver fat content was associated with higher risk of psoriasis. However, using genetic variants as a proxy for NAFLD, we did not find evidence of a causal relationship between NAFLD and psoriasis. Thus, the observational association between NAFLD and psoriasis is presumably a result of shared confounding factors or reverse causation. [ABSTRACT FROM AUTHOR]

Smoking has been associated with opposing risks of ulcerative colitis and Crohn's disease. Whether these observational associations reflect actual causal associations, confounding, or reverse causation is unclear. Using a Mendelian randomization approach, we tested the hypothesis that smoking protects against ulcerative colitis and is a cause of Crohn's disease. We included 118,683 white Danes aged ≥ 20 from the Copenhagen General Population Study (2003–2015) and the Copenhagen City Heart Study (1991–94 and 2001–03). During follow-up until 2018, we investigated the association of smoking and CHRNA3 rs1051730, where the T-allele is strongly associated with nicotine dependence, with risk of ulcerative colitis and Crohn's disease. We identified 1312 cases of ulcerative colitis and 671 cases of Crohn's disease. Compared to never-smokers, multivariable adjusted hazard ratios (HRs) for ulcerative colitis were 1.69(95% confidence interval [CI] 1.32–2.15) in former smokers and 2.27(1.74–2.96) in current smokers. Corresponding HRs for Crohn's disease were 1.31(0.93–1.84) and 1.93(1.34–2.78), respectively. Among ever-smokers when compared to non-carriers of the CHRNA3 rs1051730 T-allele, age and sex adjusted HRs for risk of ulcerative colitis were 1.03(95%CI 0.89–1.18) in heterozygotes and 0.91(0.72–1.16) in homozygotes. Corresponding HRs for Crohn's disease were 1.05(0.87–1.28) and 1.02(0.74–1.41), respectively. In a meta-analysis combined with UK Biobank, there was no evidence that CHRNA3 rs1051730 was associated with risk of ulcerative colitis or Crohn's disease. In conclusion, current versus never-smoking was associated with unexpected 2.3-fold risk of ulcerative colitis and expected 1.9-fold risk of Crohn's disease in prospective analyses; however, genetic evidence of lifelong increased smoking intensity did not support causal relationships. [ABSTRACT FROM AUTHOR]

Women with cardiovascular disease are underdiagnosed, undertreated and under-represented in research. Even though the increased risk of cardiovascular disease among patients with psoriasis is well established, only a few studies have examined women with psoriasis. This study examined the prevalence of cardiovascular risk factors and cardiovascular disease among women with psoriasis. Using the Copenhagen City Heart Study and the Copenhagen General Population Study, 66,420 women were included in a cross-sectional design. Of these, 374 (0.56%) women had hospital-diagnosed psoriasis. Women with vs without hospital-diagnosed psoriasis had higher odds ratios of having traditional cardiovascular risk factors, including hypertriglyceridaemia, smoking, obesity, type 2 diabetes, and low physical activity, and of having nontraditional cardiovascular risk factors, including low level of education, high level of psychosocial stress, and lowgrade inflammation. Compared with women from the general population, the multivariable adjusted odds ratio of heart failure and ischaemic cerebrovascular disease in women with hospital-diagnosed psoriasis was 2.51 (95% confidence interval 1.33-4.73) and 2.06 (1.27-3.35). In conclusion, women with hospital-diagnosed psoriasis have a higher prevalence of traditional and nontraditional cardiovascular risk factors, and increased risk of heart failure and ischaemic cerebrovascular disease, even after adjusting for these cardiovascular risk factors. [ABSTRACT FROM AUTHOR]

Introduction: Observational studies have found lower concentrations of plasma bilirubin in current smokers compared with former and never smokers. However, whether there is a causal relationship between smoking and bilirubin is unknown. In a Mendelian randomization analysis, we tested the hypothesis that higher tobacco consumption is causally associated with lower concentrations of plasma bilirubin.Methods: We genotyped 103 557 individuals aged 20-100 years from the Copenhagen General Population Study for the CHRNA3 rs1051730 genotype, known to be associated with higher tobacco consumption. Tobacco consumption was defined as daily and cumulative tobacco consumption.Results: In observational multivariable-adjusted analyses, a 10 g/day higher daily tobacco consumption was associated with a 0.28 µmol/L (95% confidence interval = 0.20 to 0.35) lower concentration of plasma bilirubin in current smokers, and a 10 pack-year higher cumulative tobacco consumption was associated with a 0.19 µmol/L (0.17 to 0.21) lower concentration of plasma bilirubin in former and current smokers. Using the CHRNA3 rs1051730 genotype as a proxy for daily and cumulative tobacco consumption, the difference in plasma bilirubin per T-allele was -0.12 µmol/L (-0.23 to -0.002) in current smokers and -0.09 µmol/L (-0.15 to -0.01) in current and former smokers combined. Furthermore, observationally bilirubin concentrations increased with time from smoking cessation in former smokers.Conclusion: Higher daily and cumulative tobacco consumption were associated with lower concentrations of plasma bilirubin in observational and genetic analyses, suggesting that the association is causal.Implications: Our results are compatible with two possible interpretations of previous observational studies, either that bilirubin is a mediator of smoking-induced respiratory disease or that the association between plasma bilirubin and respiratory disease stems from residual confounding because of smoking. Future studies should examine whether bilirubin is a causal risk factor for respiratory disease, or merely a marker of smoking status. [ABSTRACT FROM AUTHOR]

Background: Urate is a strong antioxidant in plasma and may protect against lung function impairment. We tested the hypothesis that high plasma urate is causally associated with better lung function and low risk of respiratory symptoms and COPD.Methods: We measured lung function and plasma urate in 114 979 individuals from the Copenhagen City Heart Study and the Copenhagen General Population Study and genotyped for SLC2A9 rs7442295 and ABCG2 rs2231142 variants, previously associated with high plasma urate, in 110 152 individuals.Results: In the two studies combined, multivariable-adjusted 100 µmol/L higher plasma urate was associated with -1.54% (95% CI -1.67 to -1.40) lower FEV1 % predicted and -1.57% (95% CI -1.69 to -1.44) lower FVC % predicted observationally; the corresponding estimates for genetically determined 100 µmol/L higher plasma urate were -0.46% (95% CI -1.17 to 0.25) and -0.40% (95% CI -1.03 to 0.23). High plasma urate was also associated with higher risk of respiratory symptoms; however, genetically determined high plasma urate was not associated with respiratory symptoms. Finally, we identified 14 151 individuals with COPD and found ORs of 1.08 (95% CI 1.06 to 1.11) for COPD observationally and 1.01 (95% CI 0.88 to 1.15) genetically per 100 µmol/L higher plasma urate.Conclusion: High plasma urate was associated with worse lung function and higher risk of respiratory symptoms and COPD in observational analyses; however, genetically high plasma urate was not associated with any of these outcomes. Thus, our data do not support a direct causal relationship. [ABSTRACT FROM AUTHOR]

Background: Genome-wide association studies have identified numerous genetic regions that influence cross-sectional lung function. Longitudinal decline in lung function also includes a heritable component but the genetic determinants have yet to be defined.Objectives: We aimed to determine whether regions associated with cross-sectional lung function were also associated with longitudinal decline and to seek novel variants which influence decline.Methods: We analysed genome-wide data from 4167 individuals from the Busselton Health Study cohort, who had undergone spirometry (12 695 observations across eight time points). A mixed model was fitted and weighted risk scores were calculated for the joint effect of 26 known regions on baseline and longitudinal changes in FEV1 and FEV1/FVC. Potential additional regions of interest were identified and followed up in two independent cohorts.Results: The 26 regions previously associated with cross-sectional lung function jointly showed a strong effect on baseline lung function (p=4.44×10-16 for FEV1/FVC) but no effect on longitudinal decline (p=0.160 for FEV1/FVC). This was replicated in an independent cohort. 39 additional regions of interest (48 variants) were identified; these associations were not replicated in two further cohorts.Conclusions: Previously identified genetic variants jointly have a strong effect on cross-sectional lung function in adults but little or no effect on the rate of decline of lung function. It is possible that they influence COPD risk through lung development. Although no genetic variants have yet been associated with lung function decline at stringent genome-wide significance, longitudinal change in lung function is heritable suggesting that there is scope for future discoveries. [ABSTRACT FROM AUTHOR]

Rationale: Whether high blood eosinophils are associated with chronic obstructive pulmonary disease (COPD) exacerbations among individuals with COPD in the general population is largely unknown.Objectives: To test the hypothesis that high blood eosinophils predict COPD exacerbations.Methods: Among 81,668 individuals in the Copenhagen General Population Study, we examined 7,225 with COPD based on spirometry. We recorded blood eosinophils at baseline and future COPD exacerbations longitudinally, defined as moderate (short-course treatment with systemic corticosteroids) or severe (hospitalization). We also assessed exacerbation risk in a subgroup of 203 individuals with clinical COPD, defined as participants with a smoking history of at least 10 pack-years, FEV1 less than 70% of predicted value, and at least one moderate or severe exacerbation in the year before baseline.Measurements and Main Results: During a median of 3.3 years of follow-up (range, 0.03-8.1), 1,439 severe and 2,864 moderate COPD exacerbations were recorded. Among all participants with COPD, blood eosinophils above versus below 0.34 × 10(9) cells per liter had multivariable-adjusted incidence rate ratios of 1.76 (95% confidence interval, 1.56-1.99) for severe exacerbations and 1.15 (1.05-1.27) for moderate exacerbations. Corresponding values in those with clinical COPD were 3.21 (2.49-4.14) and 1.69 (1.40-2.04). In contrast, using a cutpoint of 2% for blood eosinophils, the risk of exacerbations was increased for severe exacerbations only among individuals with clinical COPD and not in individuals in the broader population.Conclusions: Among individuals with COPD in the general population, increased blood eosinophil levels above 0.34 × 10(9) cells per liter were associated with a 1.76-fold increased risk of severe exacerbations. [ABSTRACT FROM AUTHOR]

Background: Permanent hair dye contains aromatic amines which are carcinogenic, and can cause allergic skin reactions. In the long term personal use of hair dye might therefore influence both morbidity and mortality. Objectives: We tested the hypothesis that personal use of hair dye in women is associated with increased morbidity and mortality in the general population. Methods: We included 7,684 women from the Copenhagen City Heart Study with information on the use of personal hair dye. We assessed the risk of cancer, skin diseases, other morbidities, and mortality during a median follow-up of 27 years (range 0–37). Results: The multivariable adjusted hazard ratio for malignant melanoma in women with versus without personal use of hair dye was 2.07 (95% confidence interval 1.25–3.42). There was no increased risk of other cancer types. For other skin diseases and other major causes of morbidity we found no differences between the two groups, except for a minor excess of digestive diseases and increased risk of Parkinson’s disease among women using hair dye. Finally, we found no difference in all-cause mortality comparing women using personal hair dye or not. After correction for multiple comparisons, none of the results remained significant. However, in sensitivity analysis the excess risk of malignant melanoma remained increased with a hazard ratio of 2.58 (95%CI 1.33–5.03) among users of personal hair dye. Conclusions: Personal use of hair dye does not have major influences on morbidity and mortality. Our finding of a 2-fold risk of malignant melanoma in women using hair dye is hypothesis generating. [ABSTRACT FROM AUTHOR]

Introduction: We hypothesized that statin use begun before the diagnosis of interstitial lung disease is associated with reduced mortality. Methods: We studied all patients diagnosed with interstitial lung disease in the entire Danish population from 1995 through 2009, comparing statin use versus no statin use in a nested 1:2 matched study. Results: The cumulative survival as a function of follow-up time from the date of diagnosis of interstitial lung disease (n = 1,786+3,572) and idiopathic lung fibrosis (n = 261+522) was higher for statin users versus never users (log-rank: P = 7·10−9 and P = 0.05). The median survival time in patients with interstitial lung disease was 3.3 years in statin users and 2.1 years in never users. Corresponding values in patients with idiopathic lung fibrosis were 3.4 versus 2.4 years. After multivariable adjustment, the hazard ratio for all-cause mortality for statin users versus never users was 0.73 (95% confidence interval, 0.68 to 0.79) in patients with interstitial lung disease and 0.76 (0.62 to 0.93) in patients with idiopathic lung fibrosis. Results were robust in all sensitivity analyses. Conclusion: Among patients with interstitial lung disease statin use was associated with reduced all-cause mortality. [ABSTRACT FROM AUTHOR]