Explanations for higher-than-expected all-cause mortality from April 2021: A scoping review.

Objectives: Many countries have continued to experience a higher-than-expected number of deaths following the peaks in mortality observed in the first year of the Covid-19 pandemic. This review aims to identify the different explanations proposed for sustained higher-than-expected mortality beyond the first pandemic year.

Study Design: Scoping review.

Methods: A systematic search of databases and grey literature sources was completed to identify English-language records proposing or investigating hypotheses for higher-than-expected mortality from April 2021 onwards in (sub)populations of high-income countries. Papers focused on survival following a diagnosis or intervention were excluded. Results were summarised narratively, and existing research prioritisation frameworks were adapted and applied to identify priorities for further research within a UK context.

Results: Seventy eligible papers were identified. Most were opinion pieces or simply presented trends; few included investigation of suggested hypotheses. Numerous explanations for higher-than-expected mortality were proposed, with hypotheses relating to direct Covid-19 mortality, sequalae of Covid-19 infection, the health service and wider impacts of the pandemic, and socioeconomic factors identified as highest-priority for further research.

Conclusions: A critical understanding of the causes of higher-than-expected mortality is essential for achieving evidence-informed policy. This review proposes priorities for further research, although these are based on author opinion only and likely to vary by setting. We did not seek to clarify the potential interactions between the hypotheses identified, however, in the UK, it is likely that the wider impacts of the Covid-19 pandemic on socioeconomic conditions have exacerbated pre-existing austerity-related trends in stalling life expectancy.