2.2-Data collection for risk factors, clinical course, and outcomes
We reviewed risk factors, clinical course, and outcomes of all patients eligible for the study. The potential risk factors for severe LRTI regarding the literature7,13–17 were abstracted from the electronic medical record. The age, gender, prematurity (<37 weeks), history of atopy (clinician-confirmed atopy), exposure to tobacco smoke (smokers in the household), malnutrition status (assessed with weight-for-height standard deviation score [SDS])18, the number and type of virus, underlying condition (immunosuppression [IS], neuromuscular disease [NMD], chronic lung disease [CLD], hemodynamically significant congenital heart disease [CHD], and previous history of LRTI), neutrophil and lymphocyte status for age19, c-reactive protein (CRP) value, oxygen requirement (defined as peripheral oxyhemoglobin saturation <92%), and admission to the ICU (defined as those admitted if they required high-flow nasal cannula oxygen [HFNCO]/bilevel positive airway pressure [BiPAP]/IMV) or short term unit were collected. Children with multiple underlying conditions were included in the group considered having a higher risk for underlying disease. Patients with IS/NMD considered the highest-risk, followed by CLD, CHD, and then the previous history of LRTI.