Acute and persistent symptoms in non-hospitalized PCR-confirmed COVID-19 patients

Reports of persistent symptoms after hospitalization with COVID-19 have raised concern of a “long COVID” syndrome. This study aimed at determining the prevalence of and risk factors for acute and persistent symptoms in non-hospitalized patients with polymerase chain reaction (PCR) confirmed COVID-19. We conducted a cohort study of non-hospitalized participants identified via the Danish Civil Registration System with a SARS-CoV-2-positive PCR-test and available biobank samples. Participants received a digital questionnaire on demographics and COVID-19-related symptoms. Persistent symptoms: symptoms > 4 weeks (in sensitivity analyses > 12 weeks). We included 445 participants, of whom 34% were asymptomatic. Most common acute symptoms were fatigue, headache, and sneezing, while fatigue and reduced smell and taste were most severe. Persistent symptoms, most commonly fatigue and memory and concentration difficulties, were reported by 36% of 198 symptomatic participants with follow-up > 4 weeks. Risk factors for persistent symptoms included female sex (women 44% vs. men 24%, odds ratio 2.7, 95% CI 1.4–5.1, p = 0.003) and BMI (odds ratio 1.1, 95% CI 1.0–1.2, p = 0.001). In conclusion, among non-hospitalized PCR-confirmed COVID-19 patients one third were asymptomatic while one third of symptomatic participants had persistent symptoms illustrating the heterogeneity of disease presentation. These findings should be considered in health care planning and policy making related to COVID-19.

Does Class Proportion of Students with Non-Western Origin in High Schools Affect Drinking Habits Among Ethnic Danish Students?

Aim the objective was to test the hypothesis that a higher proportion of students with non-Western origin in high school classes is associated with lower and less frequent alcohol consumption among ethnic Danish students. Method data on country of origin was obtained from the Danish Civil Registration System, while information on drinking habits were derived from the Danish National Youth Study 2014. Multilevel zero-inflated binominal regression was used to assess the association between class proportion of students with non-Western origin and odds of non-drinking and mean weekly alcohol consumption, while multilevel logistic regression was used to assess the association with frequent binge drinking. Results a higher proportion of students with non-Western origin in class was associated with higher odds of non-drinking among ethnic Danish student in the same class. For example, ethnic Danish boys in classes with more than 15% of the students of non-Western origin had 77% higher odds of being non-drinkers, compared to ethnic Danish boys in classes where 0–5% had non-Western origin (OR: 1.77, 95% CI; 1.42–2.20). Among ethnic Danish students that did consume alcohol, class proportion of students with non-Western origin was not associated with weekly alcohol consumption, while a higher proportion of students with non-Western origin in class was associated with lower odds of frequent binge drinking. Conclusion the downward drinking trend among adolescents in Western countries may be partly explained by the higher proportion of youth with non-Western origin, influencing the prevalence of drinking and frequency of binge drinking among adolescents in the ethnic majority population.

Turning the tide: reducing mortality among Danish merchant seafarers

ObjectivesWhile life at sea traditionally has presented a variety of potential hazards, rigorous measures have been taken in the past decades to ensure the safety and health of all aboard merchant ships. The aim of this study was to examine overall and cause-specific mortality among Danish seafarers in light of these changes.MethodsA cohort of 44 555 male (75%) and female (25%) seafarers employed on Danish ships during 1986–1999 was established through records from the Danish Seafarer Registry. Subsequently, information on vital status and causes of death was linked to members of the cohort from the Danish Civil Registration System and the Danish Register of Causes of Death using unique personal identification numbers. Standardized mortality ratios (SMRs) were calculated for the seafarers using rates from a sample of the Danish employed population.ResultsAmong seafarers with first employment prior to 1992, the overall mortality was high, with increases observed for many individual causes of death (overall SMR 1.78, 95% CI 1.72 to 1.83 for male seafarers; SMR 1.61, 95% CI 1.48 to 1.75 for female seafarers). Mortality among seafarers employed in the following period was reduced, with only a slight remaining excess of deaths. This excess in mortality was evident primarily among non-officers on board tankers and smaller ships.ConclusionsDuring recent decades, mortality among seafarers has changed, replacing the traditional image of a high-risk profession with almost normalised figures compared with the general working population. Marked imbalances in mortality according to job and ship categories have persisted though.

The Danish unique personal identifier and the Danish Civil Registration System as a tool for research and quality improvement

All countries want to improve the health of their populations and to improve the quality of care and patient safety. Consequently, there is an ongoing need to assess and document population health, the quality of care and patient safety using valid and reliable data. This requires the ability to monitor the same individuals over time as they receive prevention, diagnostics, treatments, care and rehabilitation and experience improvements or deteriorations in their health or healthcare. This is, however, a challenge for most healthcare systems. A prerequisite to such data is the unique personal identifier. This perspective on quality paper describes the experience with the unique personal identifier in Denmark, based on the Danish Civil Registration System (DCRS) as a tool for research in epidemiology, health services research, quality improvement and patient safety. DCRS has been celebrating its 50 years anniversary.

Cancer incidence among merchant seafarers: an extended follow-up of a Danish cohort

ObjectivesWhile maritime safety generally has improved dramatically over the last century, modern seafarers are still faced with numerous occupational hazards potentially affecting their risk of chronic diseases such as cancer. The aim of this study is to offer updated information on the incidence of specific cancers among both male and female seafarers.MethodsUsing records from the Danish Seafarer Registry, all seafarers employed on Danish ships during 1986–1999 were identified, resulting in a cohort of 33 084 men and 11 209 women. Information on vital status and cancer was linked to each member of the cohort from the Danish Civil Registration System and the Danish Cancer Registry using the unique Danish personal identification number. SIRs were estimated for specific cancers using national rates.ResultsThe overall incidence of cancer was increased for both male and female seafarers (SIR 1.19, 95% CI 1.15 to 1.23, and SIR 1.14, 95% CI 1.07 to 1.22) compared with the general population. This excess was primarily driven by increases in gastrointestinal, respiratory and genitourinary cancers. In addition, male seafarers working in areas with asbestos exposure showed significantly increased risk of mesothelioma. Finally, the male seafarers had an increased risk of lip cancer.ConclusionsThe majority of cancers among seafarers continue to be lifestyle-related. However, occupational exposure to asbestos and ultraviolet radiation seems to affect the cancer pattern among the male seafarers as well.

Reproduction and the risk of multiple sclerosis

Background: The incidence of multiple sclerosis (MS) in Denmark has doubled in women since 1970, whereas it has been almost unchanged in men. Objectives: To investigate whether age at first childbirth and number of births have an effect on the risk of developing MS. Methods: The cohort consisted of 1403 patients with MS of both sexes, identified through the Danish Multiple Sclerosis Registry, with clinical onset between 2000 and 2004. For each case, 25 control persons were drawn by random from the Danish Civil Registration System matched by sex, year of birth, and residential municipality. Results: More female cases than controls had no childbirths or fewer births before clinical onset ( p=0.018) but only in the last five years preceding onset ( p<0.0001). Childbirths within five years before clinical onset reduced the risk of MS onset in women: OR=0.54 (95% CI 0.41–0.70, p<0.0001) for one child and OR=0.68 (95% CI 0.53–0.87, p=0.002) for more than one child. Parental age at first childbirth had no effect on the risk of MS. Conclusions: The data did not suggest reversed causality between childbirth and MS.

Evaluation of the Quick Environmental Exposure and Sensitivity Inventory in a Danish Population

Objectives. To evaluate a Danish translation of the Quick Environmental Exposure and Sensitivity Inventory (QEESI).Methods. The study included two groups: one comprised a random sample of 2000 individuals drawn from the Danish Civil Registration System; the other comprised 315 patients with chemical intolerance.Results. The evaluation suggested good reliability for the four QEESI scales in terms of internal consistency and coefficients between test and retest scores. The discriminatory validity was the largest for the Chemical (inhalant) Intolerance and Life Impact Scales. Using combined cut-off scores for these two scales provided a sensitivity of 92.1 and a specificity of 91.8 and yielded a prevalence of 8.2% in the population group.Conclusions. The Danish translation of the QEESI showed overall good reliability and validity. We recommend the use of the combined Chemical (inhalant) Intolerance and Life Impact Scales in future studies.

No evidence of time trends in the urban–rural differences in schizophrenia risk among five million people born in Denmark from 1910 to 1986

Background. There have been conflicting reports on time trends in urban–rural differences in the incidence of schizophrenia. This study explored the potential time trends in these differences with regard to birth cohort and age at onset.Method. Linking data from the Danish Civil Registration system with data from the Danish Psychiatric Central Register, a cohort born in Denmark from 1910 to 1986 was established (5·05 million people). Overall, 23051 people were classified with schizophrenia in 1970–2001.Results. Urban–rural differences in schizophrenia risk may have existed for people born in Denmark since 1910, and have existed at a constant level for people born from 1945 to 1986. Males aged <20 years had a risk of 3·90 [95% confidence interval (CI) 3·28–4·65] associated with urban birth while males [ges ]20 years had a risk of 2·12 (1·98–2·27). Females <20 years had a risk of 2·49 (95% CI 2·01–3·09) associated with urban birth while females [ges ]20 years had a risk of 1·90 (95% CI 1·74–2·08). At age 46, 1·84% (95% CI 1·76–1·93) of males and 1·05% (95% CI 0·99–1·12) of females born in the capital area had developed schizophrenia, while 0·81% (95% CI 0·75–0·86) of males and 0·56% (95% CI 0·51–0·60) of females born in the rural area had developed schizophrenia.Conclusions. There was no evidence of time trends in the urban–rural differences in the incidence of schizophrenia in Denmark, suggesting that the cause(s) responsible for these differences were not related to exposures that became more prevalent in urban areas over time. This finding is in contrast to findings from Finland and The Netherlands.