Identification and validation of asthma phenotypes in Chinese population using cluster analysis.

BACKGROUND: Asthma is a heterogeneous airway disease, so it is crucial to clearly identify clinical phenotypes to achieve better asthma management. OBJECTIVE: To identify and prospectively validate asthma clusters in a Chinese population. METHODS: Two hundred eighty-four patients were consecutively recruited and 18 sociodemographic and clinical variables were collected. Hierarchical cluster analysis was performed by the Ward method followed by k-means cluster analysis. Then, a prospective 12-month cohort study was used to validate the identified clusters. RESULTS: Five clusters were successfully identified. Clusters 1 (n = 71) and 3 (n = 81) were mild asthma phenotypes with slight airway obstruction and low exacerbation risk, but with a sex differential. Cluster 2 (n = 65) described an "allergic" phenotype, cluster 4 (n = 33) featured a "fixed airflow limitation" phenotype with smoking, and cluster 5 (n = 34) was a "low socioeconomic status" phenotype. Patients in clusters 2, 4, and 5 had distinctly lower socioeconomic status and more psychological symptoms. Cluster 2 had a significantly increased risk of exacerbations (risk ratio [RR] 1.13, 95% confidence interval [CI] 1.03-1.25), unplanned visits for asthma (RR 1.98, 95% CI 1.07-3.66), and emergency visits for asthma (RR 7.17, 95% CI 1.26-40.80). Cluster 4 had an increased risk of unplanned visits (RR 2.22, 95% CI 1.02-4.81), and cluster 5 had increased emergency visits (RR 12.72, 95% CI 1.95-69.78). Kaplan-Meier analysis confirmed that cluster grouping was predictive of time to the first asthma exacerbation, unplanned visit, emergency visit, and hospital admission (P < .0001 for all comparisons). CONCLUSION: We identified 3 clinical clusters as "allergic asthma," "fixed airflow limitation," and "low socioeconomic status" phenotypes that are at high risk of severe asthma exacerbations and that have management implications for clinical practice in developing countries.

Anxiety but not depression symptoms are associated with greater perceived dyspnea in asthma during bronchoconstriction.

OBJECTIVE: To determine whether anxiety and depression are associated with greater respiratory discomfort in asthma. METHODS: Adults with asthma (n = 230) underwent methacholine (Mch) challenge. Anxiety and depression, asthma control, and quality of life were evaluated at study entry by using the Hospital Anxiety and Depression Scale, Asthma Control Test, and Asthma Quality of Life Questionnaire, respectively. Qualitative descriptors of breathlessness, dyspnea intensity (modified Borg scale and visual analog scale [VAS]), and other respiratory symptoms were evaluated before and after Mch challenge. RESULTS: Patients were classified as neither anxiety nor depression (NAD), anxiety only, depression only (D), or both anxiety and depression (AD) according to the Hospital Anxiety and Depression Scale score. Asthma Control Test and Asthma Control Test, and Asthma Quality of Life Questionnaire scores were lowest in the AD group (both p < 0.001). VAS scores for dyspnea and wheezing before Mch challenge were highest in the AD group (both p < 0.05). The increase in the modified Borg scale score after Mch challenge was higher in the AD group (mean [standard deviation] 2.5 ± 2.0) than in the NAD (1.5 ± 1.5) and D (0.8 ± 0.9) groups (p = 0.006 and p = 0.003, respectively). Most descriptors of breathlessness were more prevalent in the anxiety only, D, and AD groups than in the NAD group. Multivariable logistic regression models indicated that anxiety increased the risk of dyspnea (odds ratio 1.10, p < 0.001 for the Borg score; odds ratio 3.84, p = 0.032 for the VAS score) but not for other respiratory symptoms. CONCLUSIONS: Anxiety but not depression was associated with greater perceived dyspnea intensity but not other measures of respiratory discomfort in individuals with asthma. Anxiety may shape the quality and intensity of dyspnea at a given respiratory load.

Psychological status in uncontrolled asthma is not related to airway hyperresponsiveness.

BACKGROUND: Airway hyperresponsiveness (AHR) is the characteristic functional abnormality of asthma, and previous studies have shown the potential for AHR to be influenced by psychological factors, yet the relationship between anxiety and/or depression and AHR remains unclear in patients with asthma. OBJECTIVE: To explore the relationship between psychological status and AHR in asthma patients. METHODS: In a cross-sectional study, 168 adult subjects were recruited with physician-diagnosed uncontrolled asthma and a positive result for AHR in methacholine (Mch) challenge test. Psychological status, asthma control, and asthma quality of life were assessed using Zung self-rating anxiety/depression scale, asthma control test (ACT), and asthma quality of life questionnaire (AQLQ), respectively. AHR severity was evaluated and quantified by the provocative concentration of Mch, which evoked a given decrease of 20% in FEV(1). RESULTS: A total of 70.23% of recruited patients (n = 118) met the diagnostic criteria for anxiety and/or depression. There was a trend between negative psychological status and AHR in asthma patients that did not reach statistical significance, but no independent effects of negative mood states (anxiety, depression, or both) on AHR were established. Further, analyses revealed that only anxiety is associated with worse asthma control (p = 0.029), and a significant interaction effect of depression and anxiety accounted for lower asthma-related quality-of-life scores (p < 0.001). CONCLUSIONS: AHR and psychological status are loosely related to each other even if in uncontrolled asthma.