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BackgroundPersistence of physical symptoms after SARS-CoV-2 infection is a major public health concern, although evidence from large observational studies remain scarce. We aimed to assess the prevalence of physical symptoms in relation to acute illness severity up to more than 2-years after diagnosis of COVID-19.MethodsThis multinational study included 64 880 adult participants from Iceland, Sweden, Denmark, and Norway with self-reported data on COVID-19 and physical symptoms from April 2020 to August 2022. We compared the prevalence of 15 physical symptoms, measured by the Patient Health Questionnaire (PHQ-15), among individuals with or without a confirmed COVID-19 diagnosis, by acute illness severity, and by time since diagnosis. We additionally assessed the change in symptoms in a subset of Swedish adults with repeated measures, before and after COVID-19 diagnosis.FindingsDuring up to 27 months of follow-up, 22 382 participants (34.5%) were diagnosed with COVID-19. Individuals who were diagnosed with COVID-19, compared to those not diagnosed, had an overall 37% higher prevalence of severe physical symptom burden (PHQ-15 score ≥ 15, adjusted prevalence ratio [PR] 1.37 [95% confidence interval [CI] 1.23-1.52]). The prevalence was associated with acute COVID-19 severity: individuals bedridden for seven days or longer presented with the highest prevalence (PR 2.25[1.85-2.74]), while individuals never bedridden presented with similar prevalence as individuals not diagnosed with COVID-19 (PR 0.92 [0.68-1.24]). The prevalence was statistically significantly elevated among individuals diagnosed with COVID-19 for eight of the fifteen measured symptoms: shortness of breath, chest pain, dizziness, heart racing, headaches, low energy/fatigue, trouble sleeping, and back pain. The analysis of repeated measurements rendered similar results as the main analysis.InterpretationThese data suggest an elevated prevalence of some, but not all, physical symptoms during up to more than 2 years after diagnosis of COVID-19, particularly among individuals suffering a severe acute illness.FundingThis work was mainly supported by grants from NordForsk (COVIDMENT, grant number 105668 and 138929) and Horizon2020 (CoMorMent, 847776). See Acknowledgements for further details on funding.Research in contextEvidence before the studyAs the majority of the global population has contracted COVID-19, persistence of physical symptoms after SARS-CoV-2 infection (LongCOVID or post COVID-19 condition) has become a major public health concern. We searched PubMed for studies assessing physical symptoms after COVID-19, published by March 22, 2023. The search term was (physical symptoms after covid) AND LitCLONGCOVID [Pubmed filter]. We reviewed 82 studies, after excluding those not on humans or not published in English. High prevalence of multiple physical symptoms, mainly fatigue, shortness of breath, headache, muscle and chest pain, has been reported, mostly based on small samples of hospitalized patients confined to three to six months after diagnosis. A comprehensive assessment of long-term prevalence of physical symptoms beyond six months after diagnosis and among non-hospitalized patients is lacking.Added value of this studyWe included 64 880 participants from the general population of four Nordic countries, of whom 22 382 had been diagnosed with COVID-19 up to 2 years earlier (Implications of the available evidenceOur findings provide timely and valuable evidence to demonstrate the constitution of Long COVID and the long-term health consequences after recovery from COVID-19 in the general population. The long-term risk of severe physical symptom burden is distinctly associated with acute illness severity, highlighting the importance of sustained monitoring of physical symptoms among the group of patients who suffered severe acute illness course.

BackgroundThere are no methods for classifying patients with ischemic heart disease (IHD) based on the entire spectrum of pre-existing diseases. Such methods might be clinically useful due to the marked differences in presentation and course of disease.MethodsA population-based cohort study from a Danish secondary care setting of patients with IHD (2004-2016) and subjected to a coronary angiography (CAG) or coronary computed tomography angiography (CCTA). Data sources were The Danish National Patient Registry, in-hospital laboratory data, and genetic data from Copenhagen Hospital Biobank. Comorbidities included diagnoses assigned prior to presentation of IHD. Patients were clustered by means of the Markov Clustering Algorithm using the entire spectrum of registered multimorbidity. The two prespecified outcomes were: New ischemic events (including death from IHD causes) and death from non-IHD causes. Patients were followed from date of CAG/CCTA until one of the two outcomes occurred or end of follow-up, whichever came first. Biological and clinical appropriateness of clusters was assessed by comparing risks (estimated from Cox proportional hazard models) in clusters and by phenotypic and genetic enrichment analyses, respectively.FindingsIn a cohort of 72,249 patients with IHD (mean age 63.9 years, 63.1% males), 31 distinct clusters (C1-31, 67,136 patients) were identified. Comparing each cluster to the 30 others, seven clusters (9,590 patients) had statistically significantly higher or lower risk of new ischemic events (five and two clusters, respectively). 18 clusters (35,982 patients) had a higher or lower risk of death from non-IHD causes (12 and six clusters, respectively). All clusters at increased risk of new ischemic events, associated with risk of death from non-IHD causes as well. Cardiovascular or inflammatory diseases were commonly enriched in clusters (13), and distributions for 24 laboratory test results differed significantly across clusters. Clusters enriched for cerebrovascular diseases were generally not at increased risk of the two outcomes. Polygenic risk scores were increased in a total of 15 clusters (48.4%).ConclusionsClustering of patients with IHD based on pre-existing comorbidities identified subgroups of patients with significantly different clinical outcomes and presented a tool to rank pre-existing comorbidities based on their association with clinical outcomes. This novel method may support better classification of patients and thereby differentiation of treatment intensity depending on expected outcomes in subgroups.

BACKGROUND: The healthy donor effect (HDE) is a selection bias caused by the health criteria blood donors must meet. It obscures investigations of beneficial/adverse health effects of blood donation and complicates the generalizability of findings from blood donor cohorts. To further characterize the HDE we investigated how self-reported health and lifestyle are associated with becoming a blood donor, lapsing, and donation intensity. Furthermore, we examined differences in mortality based on donor status.STUDY DESIGN AND METHODS: The Danish National Health Survey was linked to the Scandinavian Donations and Transfusions (SCANDAT) database and Danish register data. Logistic- and normal regression was used to compare baseline characteristics and participation. Poisson regression was used to investigate future donation choices. Donation intensity was explored by the Anderson-Gill model and Poisson regression. Mortality was investigated using Poisson regression.RESULTS: Blood donors were more likely to participate in the surveys, OR = 2.45 95% confidence interval (2.40-2.49) than non-donors. Among survey participants, better self-reported health and healthier lifestyle were associated with being or becoming a blood donor, donor retention, and to some extent donation intensity, for example, current smoking conveyed lower likelihood of becoming a donor, OR = 0.70 (0.66-0.75). We observed lower mortality for donors and survey participants, respectively, compared with non-participating non-donors.CONCLUSION: We provide evidence that blood donation is associated with increased likelihood to participate in health surveys, possibly a manifestation of the HDE. Furthermore, becoming a blood donor, donor retention, and donation intensity was associated with better self-reported health and healthier lifestyles.

A novel risk locus at 4q32.2, located between the Nuclear Assembly Factor 1 (NAF1) and Follistatin Like 5 (FSTL5) genes, was associated with increased risk of developing colorectal cancer (CRC), with SNP rs17042479 being the most associated. However, the link between CRC development and the risk locus at 4q32.2 is unknown. We investigated the promoter activity of NAF1 and FSTL5 and analyzed the risk locus at 4q32.2 as gene regulatory region. Our results showed that the activity of the FSTL5 promoter was low compared to the NAF1 promoter. Analyses of the NAF1 promoter in conjunction with the region containing the risk locus at 4q32.2 showed that the region functions as gene regulatory region with repressor activity on NAF1 promoter activity. The SNP rs17042479(G) increased the repressor effect of the region. CRC patients’ biopsies were genotyped for SNP rs17042479(A/G), and NAF1 expression profiles were examined. We found an association between SNP rs17042479(G), cancer stage and tumor location. Additionally, patients with SNP rs17042479(G) showed lower NAF1 expression in comparison to patients with SNP rs17042479(A) in tumor tissue and the NAF1 expression in tumor tissue was lower compared to healthy tissue. The results in the study imply that reduced NAF1 expression in the tumor contribute to a more aggressive phenotype. Furthermore, this study suggests that the SNP rs17042479(G) change the expression of NAF1 and thereby increases the risk of developing CRC.

BACKGROUNDThe aim of this multinational study was to assess the development of adverse mental health symptoms among individuals diagnosed with COVID-19 in the general population by acute infection severity up to 16 months after diagnosis.METHODSParticipants consisted of 247 249 individuals from seven cohorts across six countries (Denmark, Estonia, Iceland, Norway, Scotland, and Sweden) recruited from April 2020 through August 2021. We used multivariable Poisson regression to contrast symptom-prevalence of depression, anxiety, COVID-19 related distress, and poor sleep quality among individuals with and without a diagnosis of COVID-19 at entry to respective cohorts by time (0-16 months) from diagnosis. We also applied generalised estimating equations (GEE) analysis to test differences in repeated measures of mental health symptoms before and after COVID-19 diagnosis among individuals ever diagnosed with COVID-19 over time.FINDINGSA total of 9979 individuals (4%) were diagnosed with COVID-19 during the study period and presented overall with a higher symptom burden of depression (prevalence ratio [PR] 1·18, 95% confidence interval [95% CI] 1·03-1·36) and poorer sleep quality (1·13, 1·03-1·24) but not with higher levels of symptoms of anxiety or COVID-19 related distress compared with individuals without a COVID-19 diagnosis. While the prevalence of depression and COVID-19 related distress attenuated with time, the trajectories varied significantly by COVID-19 acute infection severity. Individuals diagnosed with COVID-19 but never bedridden due to their illness were consistently at lower risks of depression and anxiety (PR 0·83, 95% CI 0·75-0·91 and 0·77, 0·63-0·94, respectively), while patients bedridden for more than 7 days were persistently at higher risks of symptoms of depression and anxiety (PR 1·61, 95% CI 1·27-2·05 and 1·43, 1·26-1·63, respectively) throughout the 16-month study period.CONCLUSIONAcute infection severity is a key determinant of long-term mental morbidity among COVID-19 patients.

It has been suggested that blood donors could have an increased risk of polycythemia vera (PV). However, no study has assessed whether frequent donors have a higher PV risk than less frequent donors.From the Scandinavian Donations and Transfusions (SCANDAT2) database, we established a cohort of blood donors who had donated whole blood at least once between 1980 and 2012. Within this cohort we first assessed the risk of PV, comparing the donors to the general population using standardized incidence ratios (SIRs) with corresponding 95% confidence intervals (CIs). To assess the association between frequency of blood donation and risk of PV we then conducted a case-control study nested within the cohort, where we compared prior donation activity among donors who were diagnosed with PV and matched controls. Here odds ratios (ORs) were used as measures of relative risk comparing donors with different donation frequency.Among 1.4 million donors in the cohort a total of 271 donors developed PV, yielding a SIR of 1.00 (95% CI, 0.89-1.13) compared to the general population. The nested case-control study showed no association between donation frequency and risk of PV. The OR of PV comparing donors who had made at least 33 donations in the period from 3 to 22 years before diagnosis of the case, to donors with one to eight donations in the same period was 1.01 (95% CI, 0.51-1.97).We find no evidence of excess risk of PV among blood donors or of an association between donation frequency and PV risk.

Background Long-term mental and physical health consequences of COVID-19 (long COVID) are a persistent public health concern. Little is still known about the long-term mental health of non-hospitalised patients with COVID-19 with varying illness severities. Our aim was to assess the prevalence of adverse mental health symptoms among individuals diagnosed with COVID-19 in the general population by acute infection severity up to 16 months after diagnosis. Methods This observational follow-up study included seven prospectively planned cohorts across six countries (Denmark, Estonia, Iceland, Norway, Sweden, and the UK). Participants were recruited from March 27, 2020, to Aug 13, 2021. Individuals aged 18 years or older were eligible to participate. In a cross-sectional analysis, we contrasted symptom prevalence of depression, anxiety, COVID-19-related distress, and poor sleep quality (screened with validated mental health instruments) among individuals with and without a diagnosis of COVID-19 at entry, 0–16 months from diagnosis. In a cohort analysis, we further used repeated measures to estimate the change in mental health symptoms before and after COVID-19 diagnosis. Findings The analytical cohort consisted of 247 249 individuals, 9979 (4·0%) of whom were diagnosed with COVID-19 during the study period. Mean follow-up was 5·65 months (SD 4·26). Participants diagnosed with COVID-19 presented overall with a higher prevalence of symptoms of depression (prevalence ratio [PR] 1·18 [95% CI 1·03–1·36]) and poorer sleep quality (1·13 [1·03–1·24]) but not symptoms of anxiety (0·97 [0·91–1·03]) or COVID-19-related distress (1·05 [0·93–1·20]) compared with individuals without a COVID-19 diagnosis. Although the prevalence of depression and COVID-19-related distress attenuated with time, individuals diagnosed with COVID-19 but never bedridden due to their illness were consistently at lower risk of depression (PR 0·83 [95% CI 0·75–0·91]) and anxiety (0·77 [0·63–0·94]) than those not diagnosed with COVID-19, whereas patients who were bedridden for more than 7 days were persistently at higher risk of symptoms of depression (PR 1·61 [95% CI 1·27–2·05]) and anxiety (1·43 [1·26–1·63]) than those not diagnosed throughout the study period. Interpretation Severe acute COVID-19 illness—indicated by extended time bedridden—is associated with long-term mental morbidity among recovering individuals in the general population. These findings call for increased vigilance of adverse mental health development among patients with a severe acute disease phase of COVID-19.Funding Nordforsk, Horizon2020, Wellcome Trust, and Estonian Research Council.