Scottish Index of Multiple Deprivation (SIMD) indicators as predictors of mortality among patients hospitalised with COVID-19 disease in the Lothian Region, Scotland during the first wave: a cohort study
Authors: Scopazzini Marcello S. , Cave Roo Nicola Rose , Mutch Callum P. , Ross Daniella A. , Bularga Anda , Chase-Topping Margo , Woolhouse Mark , Koch Oliver ,   DataLoch Covid-19 Collaborative, Anand Atul , Harrison Kathy , Hume Ally , Waugh Catriona , Stables Catherine , Brook Chloe , Duncan Chris , Homan David , Cadger Erin , Lampaki Ioanna , Daub Jennifer , McKay Jilly , Murray Neil , Harkess Ronnie , Ezu Shedrack , McCall Sophie , McLachlan Stela , Thomson Alastair , Stewart Alistair , Ene Daniella , Neilson Hazel , Caris Juergen , McMenemy Maria , Lone Nazir , Rigglesford Nicola , Schofield Paul , David Sophie , Young Stephen , McKinley Tracey , Rapson Tracey , Jamieson Anna K. , Sivakumaran Arjuna A. , Parajuli Arun , Whittaker Ed , Watson Emma K. , Le Ha Bao Trung , Preston Hannah M. M. , Yang Jason , Kelly John P. , Wubetu Jonathan , Enriquez Julia Guerrero , Knight Kathryn A. W. , Cary Louisa R. , Maltby Oscar C. N. , Callender Rosie , Goodwin Sarah H. , Clouston Thomas H. , McCormick Thomas J. , Ng XinYi , Sharif Zaina , Shah Anoop , Mehaffey Colan , Lee Ken , Woods-Dunlop Laura , Gray Michael , Mills Nicholas , Linksted Pamela , Cairns Peter , Baxter Rob , Lavenberg Stephen , Buckingham Susan , Perry Meghan R. , Mackintosh Claire L. 
Published: October 2023

Abstract
Background
Sars-CoV-2, the causative agent of COVID-19, has led to more than 226,000 deaths in the UK and multiple risk factors for mortality including age, sex and deprivation have been identified. This study aimed to identify which individual indicators of the Scottish Index of Multiple Deprivation (SIMD), an area-based deprivation index, were predictive of mortality.

Methods
This was a prospective cohort study of anonymised electronic health records of 710 consecutive patients hospitalised with Covid-19 disease between March and June 2020 in the Lothian Region of Southeast Scotland. Data sources included automatically extracted data from national electronic platforms and manually extracted data from individual admission records. Exposure variables of interest were SIMD quintiles and 12 indicators of deprivation deemed clinically relevant selected from the SIMD. Our primary outcome was mortality. Age and sex adjusted univariable and multivariable analyses were used to determine measures of association between exposures of interest and the primary outcome.

Results
After adjusting for age and sex, we found an increased risk of mortality in the more deprived SIMD quintiles 1 and 3 (OR 1.75, CI 0.99–3.08, p = 0.053 and OR 2.17, CI 1.22–3.86, p = 0.009, respectively), but this association was not upheld in our multivariable model containing age, sex, Performance Status and clinical parameters of severity at admission. Of the 12 pre-selected indicators of deprivation, two were associated with greater mortality in our multivariable analysis: income deprivation rate categorised by quartile (Q4 (most deprived): 2.11 (1.20–3.77) p = 0.011)) and greater than expected hospitalisations due to alcohol per SIMD data zone (1.96 (1.28–3.00) p = 0.002)).

Conclusions
SIMD as an aggregate measure of deprivation was not predictive of mortality in our cohort when other exposure measures were accounted for. However, we identified a two-fold increased risk of mortality in patients residing in areas with greater income-deprivation and/or number of hospitalisations due to alcohol. In areas where aggregate measures fail to capture pockets of deprivation, exploring the impact of specific SIMD indicators may be helpful in targeting resources to residents at risk of poorer outcomes from Covid-19.