Haematological and Biochemical Parameters as Predictors of Severity in COVID-19 Patients at an Isolation Centre in Ogun State, South West Nigeria

Laboratory parameters have been identified as early predictors of clinical deterioration in COVID-19, supporting risk stratification and resource allocation decisions in hospital settings. This study evaluated haematological and biochemical parameters as predictors of disease severity in COVID-19 patients managed at an isolation and treatment centre in Sagamu, Ogun State, South West Nigeria. A retrospective cross-sectional study reviewed clinical and laboratory records of 200 RT-PCR-confirmed COVID-19 patients classified by WHO severity criteria as mild, moderate, and severe. Parameters including full blood count, lymphocyte-to-CRP ratio, lactate dehydrogenase, ferritin, D-dimer, liver enzymes, and kidney function tests were extracted and compared across severity groups. Lymphopaenia was present in 41.5% of all patients and was significantly more common in severe cases at 78.6%. Elevated LDH, ferritin, and D-dimer were strongly associated with severe disease and ICU admission. The neutrophil-to-lymphocyte ratio above 3.5 had sensitivity of 82.1% and specificity of 74.3% for severe disease prediction. Elevated creatinine and liver enzymes indicated multi-organ involvement in the most critical patients. CRP above 50 mg/L at admission predicted mechanical ventilation requirement with moderate accuracy. The study confirms the utility of routinely available laboratory parameters in COVID-19 severity stratification and recommends protocol-based laboratory monitoring for all admitted COVID-19 patients to guide clinical decision-making at isolation centres across South West Nigeria. Keywords: COVID-19, haematological parameters, disease severity, lymphopaenia, D-dimer