Parental questionnaires provided reliable data on childhood asthma compared with national registers

Abstract

Background Much of our knowledge of childhood asthma comes from questionnaire‐based studies. Our main aim was to assess the agreement between parental‐reported data at 12 years of age and data from two national Swedish registers. Methods 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). Results At 12 years of age, there was substantial overall agreement between the asthma medication reported by the parents in the questionnaire and the SPDR for any asthma medication (94.8%, kappa 0.71) and maintenance treatment (95.3%, kappa 0.68). In contrast, the agreement between the outpatient asthma diagnoses in the NPR and the questionnaire‐based asthma was 30.5% and it was 32.8% between the NPR and the dispensed asthma medication in the SPDR. Hospitalization was rare for obstructive diseases after early childhood, and 38.2% of the 12‐year‐old children only received a short‐acting beta agonist, with no maintenance treatment. Conclusion There was good agreement between the questionnaire‐based data on asthma medication and the national drug register, but the National Patient Register provided incomplete information on asthma diagnoses, probably because it did not include primary care diagnoses. The results show that well‐constructed parental questionnaires can provide reliable data on childhood asthma.

Low agreement between Swedish national registers and parental questionnaires on allergic rhinitis

“…The data in this study indicate that national registers underestimate the prevalence of AR diagnosis and the use of AR medication. This is in contrast to an earlier study, where data from the same cohort showed good agreement between questionnaire data on asthma medication and the SPDR 28 . On the contrary, in that study, the NPR provided incomplete information on asthma diagnoses, most likely because visits to primary care were not included 28 .…”

“…28 On the contrary, in that study, the NPR provided incomplete information on asthma diagnoses, most likely because visits to primary care were not included. 28 The value of highly validated national registers is undeniable, and they can provide reliable data for many but not all diagnoses. 10 Register data on AR can supplement questionnaire data.…”

“…This is in contrast to an earlier study, where data from the same cohort showed good agreement between questionnaire data on asthma medication and the SPDR. 28 On the contrary, in that study, the NPR provided incomplete information on asthma diagnoses, most likely because visits to primary care were not included. 28 The value of highly validated national registers is undeniable, and they can provide reliable data for many but not all diagnoses.…”

Infants were introduced to complementary feeding earlier in 2018 compared with 2003

“…The response rate was 68.5% (5605/8176) at 6 months and 68.9% (4987/7241) at 12 months (4941 completed both questionnaires). The cohort has previously been described, 3,15 including flow charts of the study 15,16 …”

“…The cohort has previously been described, 3,15 including flow charts of the study. 15,16 Information on the introduction of complementary feeding was collected at 12 months of age. The questions on the introduction of complementary feeding are given in Table S1.…”