Clinical Profile, Laboratory Markers Predicting Severity and Outcomes of Acute Lower Respiratory Tract Infections in Under-Five Children in South India

Introduction: Acute lower respiratory tract infection (ALRI) remains a leading cause of morbidity and mortality among under-five children, particularly in India. Early identification of severe cases is critical for timely intervention, especially in resource-limited settings. This study aimed to evaluate the clinical profile and laboratory markers predicting severity and immediate outcomes of ALRI in under-five children in South India.

Methods: This prospective observational study was conducted from January 2014 to June 2015 at a tertiary care teaching hospital in South India. One hundred children aged 1 month to 5 years admitted with ALRI, defined according to WHO criteria, were enrolled. Children with chronic respiratory or cardiac illnesses were excluded. Detailed clinical evaluation and laboratory investigations, including total leukocyte count (TLC), blood culture, and chest radiography, were performed. ALRI cases were categorized into pneumonia and severe pneumonia based on WHO severity criteria. Outcomes assessed at discharge included need for oxygen supplementation, mechanical ventilation, improvement, or death. Statistical analysis was performed using the Chi-square test, with p < 0.05 considered significant.

Results: Among 100 children, 78% were classified as pneumonia and 22% as severe pneumonia. The most common presenting features were breathlessness (97%), cough (93%), fever (90%), and chest indrawing (86%). Bronchopneumonia (48%) was the most frequent diagnosis, followed by bronchiolitis (33%) and lobar pneumonia (8%). Leukocytosis was observed in 28% of cases and was significantly associated with severe pneumonia (p < 0.001). Blood culture positivity was 6% and showed significant association with disease severity (p = 0.001). Oxygen supplementation was required in 92% of cases, mechanical ventilation in 9%, and overall mortality was 3%, occurring exclusively among severe pneumonia cases.

Conclusion: Clinical features such as breathlessness, fever, cough, and chest indrawing remain key indicators of ALRI severity. Leukocytosis and positive blood culture, though less frequent, are significant predictors of severe disease. Early clinical assessment supported by selective laboratory evaluation can aid risk stratification and improve outcomes in under-five children with ALRI