Night work during pregnancy and small for gestational age: a Danish nationwide register-based cohort study.

OBJECTIVE: The aim was to investigate the association between night work during pregnancy and risk of having a small for gestational age (SGA) child. METHODS: This cohort study had payroll data with detailed information on working hours for employees in all Danish administrative regions (primarily hospital employees) between 2007 and 2015, retrieved from the Danish Working Hour Database. Pregnancies, covariates and outcome were identified from the national birth registry. We used logistic regression to investigate the association between intensity and duration of night work during the first 32 pregnancy weeks and SGA. The adjusted model included age, body mass index, socioeconomic status and smoking. Using quantitative bias analysis and G-estimation, we explored potential healthy worker survivor bias (HWSB). RESULTS: The final cohort comprised 24 548 singleton pregnancies in 19 107 women, primarily nurses and medical doctors. None of the dimensions of night work were associated with an increased risk of SGA. We found a tendency towards higher risk of SGA in pregnancies where the women stopped having night shifts during pregnancy. Using G-estimation we found an OR<1 for the association between night work and SGA if all workers continued having night work during pregnancy compared with daywork only. CONCLUSION: We found no increased risk of SGA in association with night work during pregnancy among healthcare workers. G-estimation was not precise enough to estimate the observed indication of HWSB. We need better data on pregnancy discomforts and complications to be able to safely rule out HWSB.

Occupational risk of SARS-CoV-2 infection: a nationwide register-based study of the Danish workforce during the COVID-19 pandemic, 2020-2021.

OBJECTIVE: Most earlier studies on occupational risk of COVID-19 covering the entire workforce are based on relatively rare outcomes such as hospital admission and mortality. This study examines the incidence of SARS-CoV-2 infection by occupational group based on real-time PCR (RT-PCR) tests. METHODS: The cohort includes 2.4 million Danish employees, 20-69 years of age. All data were retrieved from public registries. The incidence rate ratios (IRRs) of first-occurring positive RT-PCR test from week 8 of 2020 to week 50 of 2021 were computed by Poisson regression for each four-digit Danish Version of the International Standard Classification of Occupations job code with more than 100 male and 100 female employees (n=205). Occupational groups with low risk of workplace infection according to a job exposure matrix constituted the reference group. Risk estimates were adjusted by demographic, social and health characteristics including household size, completed COVID-19 vaccination, pandemic wave and occupation-specific frequency of testing. RESULTS: IRRs of SARS-CoV-2 infection were elevated in seven healthcare occupations and 42 occupations in other sectors, mainly social work activities, residential care, education, defence and security, accommodation and transportation. No IRRs exceeded 2.0. The relative risk in healthcare, residential care and defence/security declined across pandemic waves. Decreased IRRs were observed in 12 occupations. DISCUSSION: We observed a modestly increased risk of SARS-CoV-2 infection among employees in numerous occupations, indicating a large potential for preventive actions. Cautious interpretation of observed risk in specific occupations is needed because of methodological issues inherent in analyses of RT-PCR test results and because of multiple statistical tests.

Manager-oriented intervention to reduce absence among pregnant employees in the healthcare and daycare sector: a cluster randomised trial.

OBJECTIVE: The aim was to test if targeting managers with an educational intervention reduces absence among pregnant employees. METHODS: The study was a non-blinded cluster randomised trial conducted in hospitals and daycare institutions from two administrative Danish Regions and two Danish municipalities. Clusters (work units) were assigned randomly and non-blinded to either (1) intervention, where all managers were invited to participate in a 3-hour seminar addressing needs and options for adjustment of work in pregnancy, or (2) control, with practice as usual. The primary outcome based on payroll data was long-term pregnancy-related absence, defined as ≥12.5% cumulated absence during pregnancy weeks 1-32. Intention-to-treat analysis was applied using mixed logistic regression. RESULTS: Ninety work units were included (56 hospital departments and 34 daycare units) with 451 pregnant employees in the intervention group and 464 in the control group. Work units had on average 11 pregnant employees with no difference between the groups. 103 of the 216 invited managers (48%) participated in a the 3-hour seminar. In the intervention group, 154 (34%) had long-term pregnancy-related absence during pregnancy weeks 1-32 vs 166 (36%) in the control group. Relative odds of having long-term pregnancy-related absence, when being in the intervention group, was 1.06 (95% CI 0.71 to 1.58), with an interclass correlation coefficient of 0.07. CONCLUSION: An educational intervention targeting managers did not reduce pregnancy-related absence among pregnant employees. TRIAL REGISTRATION NUMBER: NCT03002987.

Early Occupational Intervention for People with Low Back Pain in Physically Demanding Jobs: 1-year Follow-up Results of the Randomized Controlled GOBACK Trial.

STUDY DESIGN: Randomized controlled trial with 1-year follow up. OBJECTIVE: The aim of this study was to assess whether people with low back pain (LBP) and self-reported physically demanding jobs, benefit from an occupational medicine intervention, in addition to a single hospital consultation and a magnetic resonance imaging, at 1 year of follow-up. Secondly, to examine whether the positive health effects, found in both groups at 6 months, persist at 1-year follow-up. SUMMARY OF BACKGROUND DATA: The prevalence of LBP is high in the working population, resulting in a substantial social and economic burden. Although there are many guidelines available on the management of LBP, including multidisciplinary biopsychosocial rehabilitation, they provide limited guidance on the occupational medicine aspects. METHODS: As reported previously, 305 participants with LBP and self-reported physically demanding jobs were enrolled in the randomized controlled study and randomly allocated to clinical care with additional occupational medicine intervention or clinical care alone. Data were collected at baseline, 6 months, and 1 year. Outcomes included in the present 1-year follow-up study are changes in neuropathic pain (painDETECT questionnaire), severity of pain (0-10 numerical rating scale), disability (Roland Morris Disability Questionnaire), fear-avoidance beliefs (FABQ), physical, and mental quality of life (short-form 36). RESULTS: The study showed no effect of an occupational intervention on neuropathic pain, fear-avoidance beliefs, physical and mental quality of life nor disability measured after 1 year. The positive effects found at 6 months in both groups, remained at 1-year follow-up. CONCLUSION: The results suggest that a thorough clinical consultation, with focus on explaining the cause of pain and instructions to stay active, can promote long-lasting physical and mental health in individuals with LBP. Therefore, additional occupational interventions could focus on altering occupational obstacles on a structural level.Level of Evidence: 2.

Early occupational intervention for people with low back pain in physically demanding jobs: A randomized clinical trial.

BACKGROUND: Occupational medicine seeks to reduce sick leave; however, evidence for an add-on effect to usual care is sparse. The objective of the GOBACK trial was to test whether people with low back pain (LBP) in physically demanding jobs and at risk of sick leave gain additional benefit from a 3-month complex intervention that involves occupational medicine consultations, a work-related evaluation and workplace intervention plan, an optional workplace visit, and a physical activity program, over a single hospital consultation and an MRI. METHODS AND FINDINGS: We enrolled people from the capital region of Denmark to an open-label, parallel-group randomized controlled trial with a superiority design from March 2014 through December 2015. In a hospital setting 305 participants (99 women) with LBP and in physically demanding jobs were randomized to occupational intervention (n = 153) or no additional intervention (control group; n = 152) added to a single hospital consultation giving a thorough explanation of the pain (i.e., clinical examination and MRI) and instructions to stay active and continue working. Primary outcome was accumulated sick leave days due to LBP during 6 months. Secondary outcomes were changes in neuropathic pain (painDETECT questionnaire [PDQ]), pain 0-10 numerical rating scale (NRS), Fear-Avoidance Beliefs Questionnaire (FABQ), Roland-Morris Disability Questionnaire (RMDQ), Short Form Health Survey (SF-36) for physical and mental health-related quality of life (HRQoL), and self-assessed ability to continue working (range 0-10). An intention-to-treat analysis of sick leave at 6 months showed no significant difference between groups (mean difference in days suggestively in favor of no additional intervention: 3.50 [95% CI -5.08 to 12.07], P = 0.42). Both groups showed significant improvements in average pain score (NRS), disability (RMDQ), fear-avoidance beliefs about physical activities and work (FABQ), and physical HRQoL (SF-36 physical component summary); there were no significant differences between the groups in any secondary outcome. There was no statistically significant improvement in neuropathic pain (PDQ score), mental HRQoL (SF-36 mental component summary), and self-assessed ability to stay in job. Four participants could not complete the MRI or the intervention due to a claustrophobic attack or accentuated back pain. Workplace visits may be an important element in the occupational intervention, although not always needed. A per-protocol analysis that included the 40 participants in the intervention arm who received a workplace visit as part of the additional occupational intervention did not show an add-on benefit in terms of sick leave (available cases after 6 months, mean difference: -0.43 days [95% CI -12.8 to 11.94], P = 0.945). The main limitations were the small number of sick leave days taken and that the comprehensive use of MRI may limit generalization of the findings to other settings, for example, general practice. CONCLUSIONS: When given a single hospital consultation and MRI, people in physically demanding jobs at risk of sick leave due to LBP did not benefit from a complex additional occupational intervention. Occupational interventions aimed at limiting biopsychological obstacles (e.g., fear-avoidance beliefs and behaviors), barriers in the workplace, and system barriers seem essential to reduce sick leave in patients with LBP. This study indicates that these obstacles and barriers may be addressed by thorough usual care. TRIAL REGISTRATION: Clinical Trials.gov: NCT02015572.

Physical demand at work and sick leave due to low back pain: a cross-sectional study.

OBJECTIVES: To investigate if self-reported high physical demand at work, objective physical workload using a job exposure matrix (JEM) and fear-avoidance beliefs are associated with reported sick leave in the previous year in persons with low back pain (LBP). Second, to investigate if the effects of fear-avoidance and self-reported high physical demand at work on sick leave are modified by the objective physical workloads. SETTINGS: Participants were recruited from general practice and by advertisement in a local newspaper. PARTICIPANTS: 305participants with a current period of 2-4 weeks LBP and self-reported difficulty in maintaining physically demanding jobs due to LBP were interviewed, clinically examined and had an MRI at baseline. MAIN OUTCOME MEASURES: Independent variables were high fear-avoidance, self-reported high physical demand at work and objective measures of physical workloads (JEM). Outcome was self-reported sick leave due to LBP in the previous year. Logistic regression and tests for interaction were used to identify risk factors and modifiers for the association with self-reported sick leave. RESULTS: Self-reported physically demanding work and high fear-avoidance were significantly associated with prior sick leave due to LBP in the previous year with OR 1.75 95% CI (1.10 to 2.75) and 2.75 95% CI (1.61to 4.84), respectively. No objective physical workloads had significant associations. There was no modifying effect of objective physical workloads on the association between self-reported physical demand at work/high fear-avoidance and sick leave. CONCLUSIONS: Occupational interventions to reduce sick leave due to LBP may have to focus more on those with high self-reported physical demands and high fear-avoidance, and less on individuals with the objectively highest physical workload. TRIAL REGISTRATION NUMBER: NCT02015572; Post-results.

Night work and miscarriage: a Danish nationwide register-based cohort study.

OBJECTIVE: Observational studies indicate an association between working nights and miscarriage, but inaccurate exposure assessment precludes causal inference. Using payroll data with exact and prospective measurement of night work, the objective was to investigate whether working night shifts during pregnancy increases the risk of miscarriage. METHODS: A cohort of 22 744 pregnant women was identified by linking the Danish Working Hour Database (DWHD), which holds payroll data on all Danish public hospital employees, with Danish national registers on births and admissions to hospitals (miscarriage). The risk of miscarriage during pregnancy weeks 4-22 according to measures of night work was analysed using Cox regression with time-varying exposure adjusted for a fixed set of potential confounders. RESULTS: In total 377 896 pregnancy weeks (average 19.7) were available for follow-up. Women who had two or more night shifts the previous week had an increased risk of miscarriage after pregnancy week 8 (HR 1.32 (95% CI 1.07 to 1.62) compared with women, who did not work night shifts. The cumulated number of night shifts during pregnancy weeks 3-21 increased the risk of miscarriages in a dose-dependent pattern. CONCLUSIONS: The study corroborates earlier findings that night work during pregnancy may confer an increased risk of miscarriage and indicates a lowest observed threshold level of two night shifts per week.

Night work and sick leave during pregnancy: a national register-based within-worker cohort study.

OBJECTIVE: The aim of our study was to investigate the acute effect of night work during pregnancy on the risk of calling in sick the following day using register-based information and the workers as their own controls. METHODS: Using the payroll-based national Danish Working Hour Database, including all public hospital employees in Denmark, we identified 9799 pregnant women with ≥1 day shift and ≥1 night shift and ≥1 day of sick leave during the first 32 pregnancy weeks from January 2007 to December 2013. We performed fixed effects logistic regression, that is, within-worker comparisons, of the risk of sick leave of any duration starting within 24 hours after night shifts of different length versus day shifts. RESULTS: Most of the participants were nurses (64%) or physicians (16%). We found an increased relative risk of sick leave following night shifts compared with day shifts during all pregnancy trimesters. The risk was highest for night shifts lasting >12 hours (OR 1.37, 95% CI 1.15 to 1.63 for nurses; OR 1.87, 95% CI 1.69 to 2.08 for physicians) and among women aged >35 years (OR 1.42, 95% CI 1.24 to 1.63). CONCLUSION: Among Danish public hospital employees night shifts during pregnancy, especially shifts longer than 12 hours, increased the risk of calling in sick the following day independent of personal factors and time-invariant confounders in all pregnancy trimesters.