Factors associated with severe pneumonia in adults hospitalised with community-acquired pneumonia in Mongolia

Limited research has focused on risk factors for community acquired pneumonia (CAP) in adults in low-middle income countries (LMICs). Mongolia has high rates of CAP hospitalisations with extreme winter temperatures and significant air pollution. We aimed to examine risk factors for severe CAP among hospitalised adults aged ≥ 18 years in Mongolia. Adults hospitalised with clinical CAP were enrolled over three years (2019–2022) into a prospective CAP surveillance program in four district hospitals in the capital city, Ulaanbaatar. Participants had clinical information and risk factors collected using a case report form. Nasopharyngeal swabs were collected and tested for Streptococcus pneumoniae (the pneumococcus), influenza and respiratory syncytial virus, while collected urine was tested for the pneumococcus. From 2020 only patients with a negative SARS-CoV-2 test were enrolled in the study. Severe CAP was defined as clinical CAP with intensive care unit admission or ≥ 2 severity signs (confusion, hypotension, tachypnoea or hypoxaemia). Multivariable logistic regression was used to derive adjusted risk factor estimates. Overall, 3178 participants met the CAP study case definition and 10.1% had severe CAP. Pneumococcal carriage (aOR:2.67; 95% CI:1.88–3.79; p < 0.001), pneumococcal serotype-specific urine antigen detection positivity (aOR:1.69; 95% CI:1.11–2.57; p = 0.01), hospital admission within the last year (aOR:1.73; 95% CI:1.26–2.37; p = 0.001), underlying medical conditions (aOR:1.96; 95% CI:1.39–2.76; p < 0.001), cigarette smoking (aOR:1.53; 95% CI:1.08–2.16; p = 0.01) and alcohol intake (aOR:2.19; 95% CI:1.49–3.22; p < 0.001), were identified as risk factors for severe CAP on multivariable analysis. We identified key risk factors for severe CAP in hospitalised adults in urban Mongolia. If resources are limited, this data could be used to prioritise groups for vaccinations, alongside public health policies to decrease tobacco smoking and alcohol consumption.