Factors Influencing Gender Differences in the Diagnosis and Treatment of Asthma in Childhood: the Tucson Children's Respiratory Study

Studies identified gender differences in diagnosed asthma, but the extent to which they can be attributed to differences in symptom experience and frequency rather than factors influencing diagnosis has not been established. We investigated prevalence of, and consultation for, asthma symptoms, as well as diagnosis and treatment in 533 boys and 556 girls enrolled in the Tucson Children's Respiratory Study, a population-based birth-cohort study. Questionnaires regarding respiratory symptoms and diagnoses were obtained at ages 2, 3, 6, 8, 11, 13, 16, and 18 years. Boys were significantly more likely than girls to experience both wheeze and frequent wheeze most years in the first decade of life. However, girls with symptoms were less likely than boys to see a physician (74.1% vs. 83.4%, P < 0.001) and to be labeled as having asthma (43.3% vs. 53.8%, P < 0.009), even after adjusting for symptom frequency. A difference in symptom presentation also appeared to influence diagnosis: nocturnal cough without frequent wheeze was more prevalent among girls, and was associated with reduced diagnosis of asthma. Among subjects who consulted a physician for wheeze, boys were significantly more likely than girls to have taken medication (81.5% vs. 73.5%, P < 0.01). The lag time between age at first wheeze and first use of medication among those consulting a physician for wheeze or asthma was greater for girls, especially among subjects with frequent wheeze (2.8 vs. 1.6 years, P < 0.005). These findings indicate that gender differences in the diagnosis and treatment of asthma cannot be explained completely by differences in symptom prevalence and frequency.