Parental questionnaires provided reliable data on childhood asthma compared with national registers
Data were obtained from the prospective, longitudinal, population‐based Children of Western Sweden cohort, which focused on children born in 2003. The parents answered questionnaires at six months and one, four, eight and 12 years of age. Personal identity numbers linked 3634 children to the Swedish Prescribed Drug Register (SPDR) and the National Patient Register (NPR). Read more at Parental ques