Abstract
Many western countries used shielding (extended self-isolation) of people presumed to be at high-risk from COVID-19 to protect them and reduce healthcare demand. To investigate the effectiveness of this strategy, we linked family practitioner, prescribing, laboratory, hospital and death records and compared COVID-19 outcomes among shielded and non-shielded individuals in the West of Scotland. Of the 1.3 million population, 27,747 (2.03%) were advised to shield, and 353,085 (26.85%) were classified a priori as moderate risk. COVID-19 testing was more common in the shielded (7.01%) and moderate risk (2.03%) groups, than low risk (0.73%). Referent to low-risk, the shielded group had higher confirmed infections (RR 8.45, 95% 7.44–9.59), case-fatality (RR 5.62, 95% CI 4.47–7.07) and population mortality (RR 57.56, 95% 44.06–75.19). The moderate-risk had intermediate confirmed infections (RR 4.11, 95% CI 3.82–4.42) and population mortality (RR 25.41, 95% CI 20.36–31.71) but, due to their higher prevalence, made the largest contribution to deaths (PAF 75.30%). Age ≥ 70 years accounted for 49.55% of deaths. In conclusion, in spite of the shielding strategy, high risk individuals were at increased risk of death. Furthermore, to be effective as a population strategy, shielding criteria would have needed to be widely expanded to include other criteria, such as the elderly.
Highlights
Many western countries used shielding of people presumed to be at high-risk from COVID-19 to protect them and reduce healthcare demand
In the COVID-19 pandemic, a major concern was that the demand on health services would exceed capacity in terms of hospitalisations, intensive care unit (ICU) admissions, and v entilation[1]; policy-makers sought interventions that could flatten the curve in severe cases to avoid hospitals becoming overwhelmed
COVID-19 risk scores are being developed in an attempt to improve identification of high risk individuals who could be advised to shield[11] but attempts to investigate the potential contribution of a shielding strategy to population-level outcomes and healthcare demands have so far been largely limited to mathematical modelling[12,13,14,15,16,17,18,19,20]
Summary
Many western countries used shielding (extended self-isolation) of people presumed to be at high-risk from COVID-19 to protect them and reduce healthcare demand. Linkage of family practitioner records of 17 million people in England reported a wide range of long-term conditions associated with in-hospital death from COVID-19 including: respiratory, heart, liver and kidney disease, diabetes, cancers, stroke and organ transplantation[10]. COVID-19 risk scores are being developed in an attempt to improve identification of high risk individuals who could be advised to shield[11] but attempts to investigate the potential contribution of a shielding strategy to population-level outcomes and healthcare demands have so far been largely limited to mathematical modelling[12,13,14,15,16,17,18,19,20]
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