Cohort profile: the Leicester Respiratory Cohorts

Asthma and other wheezing disorders are the most common chronic health problems in childhood and place a large burden on children, their families and society.1 Prevalence is highest in infancy or early childhood and the aetiology is complex, with a strong influence of intrauterine and early life exposures. Clinical presentation, response to treatment and prognosis differ by age and the natural history is highly variable. It has been questioned whether asthma, especially in young children, should be regarded as one disease with a single underlying aetiology but a wide range of severity,2 or as a syndrome comprising several separate conditions.3,,4 Furthermore, respiratory illness in early life is associated with adult respiratory disease and diminished lung function.5,,6 Despite this, most epidemiological studies of asthma before the 1990s had focused on schoolchildren and adults, and there were sparse population-based data on infants and preschool children. The Leicester respiratory cohort studies were set up to fill this gap.