Risk of pneumonia in relation to body mass index in Australian Aboriginal people.

This study examined the relationship between body mass index (BMI) and the risk of pneumonia in Aboriginal Australians. A total of 677 adults aged 20-60 years were followed up from the baseline examination during 1992-1995 to June 2012. The pneumonia events were identified through hospital records. Pneumonia incident rates were calculated according to BMI groups. Hazard ratios were computed using Cox regression adjusting for age, smoking and alcohol consumption status. The incident rate of pneumonia was 13.3/1000 person-years, and this rate was significantly higher in females than males (hazard ratio = 1.5). Compared to males with normal BMI (18.5-24.9 kg/m²), the adjusted hazard ratio was 3.5 for males with lowest BMI (P < 0.01). Low BMI was significantly associated with a higher risk of hospitalized pneumonia for Aboriginal males. However, the U-shaped trend of this association indicates that the risk of pneumonia is likely to be associated with both low and high BMI.