Mortality in Norway and Sweden Before and After the Covid-19 Outbreak: A

Mortality in Norway and Sweden Before and After the Covid-19 Outbreak: A

medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. Mortality in Norway and Sweden before and after the Covid-19 outbreak: a cohort study Frederik E Juul, medical doctor1*; Henriette C Jodal, medical doctor1*; Ishita Barua, medical doctor1*; Erle Refsum, postdoctoral fellow1; Ørjan Olsvik, professor2; Lise M Helsingen, medical doctor1; Magnus Løberg, associate professor1; Michael Bretthauer, professor1#; Mette Kalager, professor1#; Louise Emilsson, associate professor1,3,4,5# *These authors have contributed equally #These authors have contributed equally 1Clinical Effectiveness Research Group, Oslo University Hospital and University of Oslo, Oslo, Norway 2Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromso, Norway 3Department of General Practice, University of Oslo, Oslo, Norway 4Vårdcentralen Årjäng & Centre for Clinical Research, Värmland län, Sverige 5Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden Corresponding author: Frederik E Juul, MD Clinical Effectiveness Research Group University of Oslo Box 1089 Blindern, 0317 Oslo E-mail: f.e.juul@medisin.uio.no PhoneNOTE: This: +47 preprint 975 reports 12 966 new research that has not been certified by peer review and should not be used to guide clinical practice. 1 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. Word count: 2537 Abstract: 299 2 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. Abstract Objectives Norway and Sweden are similar countries regarding ethnicity, socioeconomics and health care. To combat Covid-19, Norway implemented extensive measures such as school closures and lock-downs, while Sweden has been criticised for relaxed measures against Covid-19. We compared the effect of the different national strategies on all-cause and Covid-19 associated mortality. Design Retrospective cohort. Setting The countries Norway and Sweden. Participants All inhabitants. Main outcome measures We calculated weekly mortality rates (MR) with 95% confidence intervals (CI) per 100,000 individuals as well as mortality rate ratios (MRR) comparing the epidemic year (29th July, 2019 to 26th July, 2020) to the four preceding years (July 2015 to July 2019). We also compared Covid-19 associated deaths and mortality rates for the weeks of the epidemic in Norway and Sweden (16th March to 26th July, 2020). Results In Norway, mortality rates were stable during the first three 12-month periods of 2015/16; 2016/17 and 2017/18 (MR 14.8 to 15.1 per 100,000), and slightly lower in the two most recent periods including during epidemic period (2018/19 and 2019/20; 14.5 per 100,000). In Sweden, all-cause mortality was stable during the first three 12-month periods of 2015/16; 2016/17 and 2017/18 (MR 17.2 to 17.5 per 100,000), but lower in the year 2018/19 3 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. immediately preceding the epidemic (16.2 per 100,000). Covid-19 associated mortality rates were 0.2 per 100,000 (95%CI 0.1 to 0.4) in Norway and 2.9 (95%CI 1.9 to 3.9) in Sweden. The increase in mortality was confined to individuals in 70 years or older. Conclusions All-cause mortality remained unaltered in Norway. In Sweden, the observed increase in all- cause mortality during Covid-19 was partly due to a lower than expected mortality preceding the epidemic and the observed excess mortality, was followed by a lower than expected mortality after the first Covid-19 wave. This may suggest mortality displacement. Strengths and limitations of this study: 1. Compares two similar contries in all aspects but the handling of the Covid-19 epidemic 2. Evaluates the mortality for several years before and during the epidemic 3. Provides a possible explanation of the observed mortality changes 4. Discusses the socioeconomic effects of the different strategies in the two countries 5. Does not evaluate cause-specific mortality 4 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. Introduction Covid-19 was declared an international health crisis by the WHO on 30th January, and a pandemic on 11th March, 2020 (1,2). As of 17th September, 945,962 deaths have been officially recorded as a consequence of the disease worldwide (3), and some claim that the death toll is even higher (4,5). Assessments of the burden of Covid-19 have been hampered by lack of comprehensive data on the disease and of the benefits and harms of the measures against it (6). Cause-specific death rates are prone to bias, especially for a disease with a high asymptomatic burden and large differences in testing and reporting of causes of death between countries. Therefore, all- cause mortality trends may provide a more reliable alternative to assess burden of an epidemic in different countries and regions (4,5). Norway and Sweden are similar countries regarding ethnicity, governmental and administrative systems, socioeconomics and public health care systems, and both countries have reliable, timely and complete registration of deaths (7,8). To combat the epidemic, Norway implemented extensive measures such as school closures and lock-downs, and reported few Covid-19 associated deaths and little severe disease. Sweden, on the other hand, reported more Covid-19 associated deaths and disease, and has been criticised for their relaxed measures against Covid-19 (9). The substantially different national strategies to control the Covid-19 epidemic in the two countries is a natural experiment that enables difference-in-difference analyses (10) to evaluate the benefits and harms associated with the epidemic and its measures. 5 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. To this end, we compared all-cause mortality and Covid-19 associated deaths in Norway and Sweden, before and during the epidemic, in light of the different measures against Covid-19. Methods Covid-19 and mitigation measures in Norway and Sweden The first Covid-19 associated death occurred in Norway on 12th March and in Sweden on 11th March, 2020 (11,12). On 12th March, the Norwegian government introduced extraordinary measures against the epidemic (Table 1); emergency laws required closure of all day care centres, schools, universities and other academic institutions, as well as gyms, hair salons, restaurants and movie theatres. Domestic and international travel restrictions, including a total ban for international travel for health care workers, were introduced, and all sport and cultural events as well as all organised sports were cancelled (13,14). The Norwegian government urged the population to stay at home if possible, and contacts with health care services were encouraged only if absolutely necessary (13–16). Most appointments for patients with chronic diseases were cancelled, while some were replaced with telephone and video consultations (17–19). In Sweden, measures were considerably less strict (Table 1); on 29th March, the Swedish Government banned public gatherings and events with more than 50 people (20,21). The Public Health Agency recommended high schools and universities to remain open, but teach online if possible (22); non-essential travel should be avoided (23). People with respiratory symptoms should stay at home (24), and some elective surgery was postponed (25), but otherwise the health care service in Sweden operated as before. Restaurants and bars, gyms, hair salons and movie theatres stayed open, and sports and cultural events continued during the epidemic (20,21). 6 medRxiv preprint doi: https://doi.org/10.1101/2020.11.11.20229708; this version posted November 13, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. Starting 12th March, both countries strongly emphasised general measures against Covid-19; social distancing with preferred distance of at least 1 meter; hand wash and disinfection, and self-quarantine for all individuals with symptoms suggestive of Covid-19. Contact tracing, isolation and follow-up of Covid-19 transmission was strictly enforced by public health authorities in both countries (26,27). Data sources Norway and Sweden have similar, single-payer, public health care systems with universal coverage. In each country, all residents are assigned an individually unique national registration number, which provides information on sex and date of birth and allows linkage to national registers with data on socioeconomics characteristics, health and disease, hospitalisation and death.

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