# Chronic respiratory diseases risk during the COVID-19 pandemic: an integrated modelling approach based on hospital records across 30 countries

## TL;DR

This study analyzed hospital records from 30 countries to understand how individual, environmental, and viral factors affect the severity and mortality of chronic respiratory disease patients with COVID-19.

## Contribution

The study introduces an integrated modeling approach to quantify and compare the impact of multiple risk factors on CRD-COVID outcomes across different patient groups.

## Key findings

- Older patients exposed to low humidity had the highest risk of severe outcomes and mortality.
- Environmental factors like humidity and air pollutants significantly influenced admission severity and mortality.
- Individual, environmental, and viral factors contributed differently to outcomes in asthma, chronic pulmonary disease, and ACO patients.

## Abstract

Globally, there are significant inequalities in risk for chronic respiratory disease patients with COVID-19 (CRD-COVID), and a comprehensive understanding of its determinants and their interactions is needed. This study quantified individual, environmental, and viral risks that impact hospital admission severity and survival outcomes in CRD-COVID patients utilizing multinational hospital records.

We analysed data on CRD-COVID from the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) dataset, covering January 2020 to July 2022 across 30 countries. The cohort included COVID-19 patients with asthma (Asthma, n = 36,365), chronic pulmonary disease (CPD, n = 36,332), and asthma-CPD overlap (ACO, n = 16,061). We matched these patients with their prehospital environmental and viral risk factors. The primary outcome was admission severity, which we assessed using generalised linear mixed models (GLMM), and GPBoost with Shapley Additive Explanations (SHAP) algorithm. The secondary outcome was 28-day mortality, evaluated using Cox regression and K-medoids clustering.

The rates of severe admissions and 28-day mortality were 33.7% and 16.4% for the asthma cohort, 30.1% and 31.6% for the CPD cohort, and 15.9% and 25.8% for the ACO cohort, respectively. Common key risk factors impacting admission severity in CRD-COVID patients include age, sex, comorbidities, humidity, precipitation, and O3 concentration, while vaccination status, temperature, and SO2 concentration were only significant in asthma patients. The interactions analysis showed low Humidity had a greater impact on patients over 60 years of age and those with comorbid hypertension. Individual, environmental, and viral factors accurately predicted admission severity, and their contribution was different for asthma (58% individual, 28% environmental, and 14% viral variants), CPD (57%, 33%, and 10%) and ACO (63%, 31%, and 6%) patients. Four clusters stratified by these risk factors within each disease group showed significant differences in 28-day mortality rates, particularly in the asthma and CPD patients. The cluster with the highest 28-day mortality rates featured low humidity (mean 55.5% for asthma, 54.4% for CPD) and older age (60.1 and 74.2 years).

The impact of prehospital individual, environmental, and viral risk on the severity of CRD-COVID patients was heterogeneous. Older people exposed to low humidity were at greatest risk.

The online version contains supplementary material available at 10.1186/s12963-025-00412-x.