This study aimed to quantify how patient risk factors relate to COVID-19 severity across categories 1–5 in a prospective, hospital-based cohort. We hypothesised that greater severity would be associated with higher odds of intensive care unit (ICU) admission and in-hospital mortality. Secondary aims were to assess associations with age, viral variants, symptom clusters, lymphocyte count, fasting blood glucose and cytokine profiles.

Prospective cohort study.

A secondary-care/tertiary-care hospital and linked community settings in Cheras, Kuala Lumpur, Malaysia.

This study was nested within the COVGEN project, a prospective COVID-19 cohort conducted at Hospital Canselor Tuanku Muhriz UKM (HCTM), Cheras Health Clinic and the Bandar Tun Razak COVID-19 Assessment Centre in Cheras, Kuala Lumpur, Malaysia, from 1 August 2021 to 31 October 2022. 2532 participants were enrolled at baseline. Eligible participants were Malaysian citizens aged 12–18 years (paediatric/adolescent) or ≥18 years who had reverse transcription-polymerase chain reaction–confirmed COVID-19 at recruitment and resided in Kuala Lumpur or Selangor. Patients who had a clinically unstable condition and those who declined participation (personally or via a next-of-kin or legal representative) were excluded. This analysis included 559 patients hospitalised at HCTM; after excluding five with incomplete questionnaires, 554 remained for analysis (413 admitted to general wards and 141 to ICUs). Categories 3–5 comprised hospitalised patients, whereas categories 1–2 included hospitalised individuals and a subset recruited from community settings.

Primary outcomes included disease severity (categories 4–5 vs 1–3), ICU admission and in-hospital mortality. Secondary outcomes included associations with age strata, viral variant (delta vs omicron), symptom clusters, lymphocyte count, fasting blood glucose and cytokines: interferon gamma-inducible protein 10, interferon gamma, interleukins 8, 10, 2, 6 and 7 and tumour necrosis factor alpha.

141 of 554 (25.5%) patients required ICU care. Compared with milder categories, category 5 was associated with markedly higher odds of ICU admission (OR 204.50; 95% CI 37.54 to 1114.18; p55 versus

An increasing clinical severity category was strongly associated with ICU admission and mortality. Age, delta infection, specific symptom clusters, lymphopenia, hyperglycaemia and pro-inflammatory cytokines identified higher-risk patients, supporting risk-stratified management and prioritisation for enhanced monitoring.