Asthma is a chronic disease causing psychological stress which leads to the activation of hypothalamus-pituitary-adrenal axis. The purpose of this study is to compare morning salivary cortisol levels in persistent asthma patients according to their disease severities and control status. Total 206 adult asthma patients were recruited from four university hospitals. Spirometry, questionnaire of Asthma Quality of Life (AQOL) and Asthma Control Test (ACT) were completed, and saliva samples were collected prospectively to measure morning cortisol level. The mean patient age was 56.5±15.3 years with mean asthma duration of 9.1±11.1 years. Sixty five patents (31.6%) were classified as mild persistent asthma, and 141 patients (68.4%) were classified as moderate persistent asthma according to the Expert Panel Report 3. The mean predicted FEV1 was 88.8%±18.4%, and the methacholine PC20 was 9.6±8.5 mg/mL in all study population. The mean ACT score for all patients was 19.9±3.6, and there were 71 (34.5%) patients in poorly controlled and 135 (65.5%) in well controlled asthma. The poorly controlled asthma patients were characterized by significantly lower FEV1 (84.6%±17.6% vs 91.1%±18.5%, P=0.018), lower AQOL scores (46.0±13.9 vs 73.8±26.3, P<0.001), and lower salivary cortisol levels (0.14±0.08 vs 0.18±0.11 µg/dL, P=0.04) compared to well controlled asthma. The ACT score was significantly related to salivary cortisol levels (P=0.034) after adjusting for age. There was no significant difference in salivary cortisol levels (0.17±0.12 vs 0.16±0.08, P=0.725) when analyzed according to the dose of used corticosteroid and lung function. Asthma control status affects morning salivary cortisol level. Measuring the morning salivary cortisol level might be a simple and new way to assess asthma control status.
Keywords: Asthma; asthma control test; salivary cortisol; stress.