Lockdown and non-COVID-19 deaths: cause-specific mortality during the first wave of the 2020 pandemic in Norway: a population-based register study.

Objective: To explore the potential impact of the first wave of COVID-19 pandemic on all cause and cause-specific mortality in Norway.

Design: Population-based register study.

Setting: The Norwegian cause of Death Registry and the National Population Register of Norway.

Participants: All recorded deaths in Norway from March to May from 2010 to 2020.

Main Outcome Measures: Rate (per 100 000) of all-cause mortality and causes of death in the European Shortlist for Causes of Death from March to May 2020. The rates were age standardised and adjusted to a 100% register coverage and compared with a 95% prediction interval (PI) from linear regression based on corresponding rates for 2010-2019.

Results: 113 710 deaths were included, of which 10 226 were from 2020. We did not observe any deviation from predicted total mortality. There were fewer than predicted deaths from chronic lower respiratory diseases excluding asthma (11.4, 95% PI 11.8 to 15.2) and from other non-ischaemic, non-rheumatic heart diseases (13.9, 95% PI 14.5 to 20.2). The death rates were higher than predicted for Alzheimer's disease (7.3, 95% PI 5.5 to 7.3) and diabetes mellitus (4.1, 95% PI 2.1 to 3.4).

Conclusions: There was no significant difference in the frequency of the major causes of death in the first wave of the 2020 COVID-19 pandemic in Norway compared with corresponding periods 2010-2019. There was an increase in diabetes mellitus and Alzheimer's deaths. Reduced mortality due to some heart and lung conditions may be linked to infection control measures.