High incidence of respiratory disease in Australian infants despite low rate of maternal cigarette smoking

Aim The burden of wheezing illnesses in Australian infants has not been documented since the success of initiatives to reduce maternal cigarette smoking. We aimed to determine the incidence of wheeze and related health-care utilisation during the first year of life among a contemporary Australian birth cohort. Methods A birth cohort of 1074 infants was assembled between 2010 and 2013. Parents completed questionnaires periodically. Several non-exclusive infant respiratory disease phenotypes were defined, including any wheeze, wheeze with shortness of breath and recurrent wheeze. Skin prick testing was performed to determine atopic wheeze. Health-care utilisation for respiratory disease was determined from questionnaires and hospital medical records. Results Retention to 1 year was 840/1074 (83%). The incidence of any wheeze was 51.8% (95% confidence interval (CI) 48.3-55.2%), wheeze with shortness of breath 20.6% (95% CI 17.9-23.5), recurrent wheeze 19.4% (95% CI 16.8-22.2) and atopic wheeze 6% (95% CI 4.6-7.8). Respiratory illness resulted in primary health-care utilisation in 82.2% (95% CI 79.3-84.8) of participants and hospital presentation in 8.8% (95% CI 7.2-10.6). Maternal smoking during pregnancy was uncommon (15.7%) and was not associated with wheeze or health resource utilisation. Male gender, familial atopy and asthma and smaller household size were associated with a higher incidence of wheeze. Conclusions The incidence of wheezing illness among Australian infants remains high despite relatively low rates of maternal smoking during pregnancy. The majority of the health-care burden is borne by primary health-care services. Further research is required to inform novel prevention strategies.