title: Clinical risk factors for life-threatening lower respiratory tract infections in children: a retrospective study in an urban city in Malaysia.
abstract: OBJECTIVE
  Lower respiratory tract infections (LRTIs) are an important cause of morbidity and mortality, especially in low income countries. The aim of this study was to determine risk factors of life-threatening LRTIs in hospitalised children in Malaysia.
  
  
  METHODS
  This retrospective study included children aged less than 18 years admitted for LRTIs over 13 months in a tertiary referral centre in Kuala Lumpur, Malaysia. Neonates, children with asthma and those with either no or a normal chest radiograph were excluded. Life-threatening infection was defined as that needing non-invasive ventilation or admission to the paediatric intensive care unit. Routine blood investigations and nasopharyngeal secretion results (bacterial and viral) were obtained. Chest radiographs were reviewed by a designated radiologist. Environmental data (rainfall, particulate matter ≤ 10 µm [PM10] and air pollution index [API]) was obtained from the respective government departments.
  
  
  RESULTS
  Three hundred and ninety-one episodes of LRTIs were included. Viruses were implicated in 48.5% of LRTIs, with respiratory syncytial virus (RSV) being detected in 44% of viral LRTIs. Forty-six (11.8%) children had life-threatening disease and the overall mortality rate was 1.3% (5 children). RSV was detected in 26% of children with life-threatening LRTIs. In multivariate logistic regression, chronic lung disease, presenting history of apnoea and signs of hypoxia, was associated with life threatening LRTIs. Increased LRTI admissions were associated with low rainfall but not PM10 nor API. Of those on follow-up, 39% had persistent respiratory symptoms.
  
  
  CONCLUSIONS
  One in nine children admitted with LRTI had a life-threatening LRTI. The aetiology was viral in almost half of admitted children. RSV was detected in a quarter of children with life-threatening LRTIs. Children who present with LRTIs and either have chronic lung disease, presenting history of apnoea or signs of hypoxia, should be observed carefully as the risk of deterioration to life-threatening illness is high.
authors.affiliation: Department of Paediatrics, University Malaya Medical Centre, Kuala Lumpur, Malaysia; University Malaya Paediatrics and Child Health Research Group, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: Anna Marie
authors.initials: AM
authors.lastname: Nathan
authors.affiliation: Department of Obstetrics and Gynaecology, Hospital Sultan Haji Ahmad Shah, Temerloh, Pahang, Malaysia.
authors.forename: Fairuz
authors.initials: F
authors.lastname: Rani
authors.affiliation: Department of Medicine, Raigmore Hospital, Inverness, Scotland, United Kingdom.
authors.forename: Rachel Jiun Yi
authors.initials: RJ
authors.lastname: Lee
authors.affiliation: Julius Centre University of Malaya, Department of Social & Preventive Medicine, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: Rafdzah
authors.initials: R
authors.lastname: Zaki
authors.affiliation: Department of Biomedical Imaging, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: Caroline
authors.initials: C
authors.lastname: Westerhout
authors.affiliation: Department of Medical Microbiology, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: I-Ching
authors.initials: IC
authors.lastname: Sam
authors.affiliation: Department of Paediatrics, University Malaya Medical Centre, Kuala Lumpur, Malaysia; University Malaya Paediatrics and Child Health Research Group, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: Lucy Chai See
authors.initials: LC
authors.lastname: Lum
authors.affiliation: Department of Paediatrics, University Malaya Medical Centre, Kuala Lumpur, Malaysia; University Malaya Paediatrics and Child Health Research Group, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: Jessie
authors.initials: J
authors.lastname: de Bruyne
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001424:Bacterial Infections / Q000382:microbiology / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008296:Malaysia / Q000453:epidemiology; D008297:Male; D012141:Respiratory Tract Infections / Q000382:microbiology / Q000401:mortality*; D012189:Retrospective Studies; D012307:Risk Factors; D014505:Urban Population; D014777:Virus Diseases / Q000401:mortality / Q000821:virology