Assessment of asthma control and asthma exacerbations in the epidemiology and natural history of asthma: outcomes and treatment regimens (TENOR) observational cohort

Abstract

Patients with severe or difficult-to-treat asthma account for substantial asthma morbidity, mortality, and healthcare burden despite comprising only a small proportion of the total asthma population. TENOR, a multicenter, observational, prospective cohort study was initiated in 2001. It enrolled 4,756 adults, adolescents and children with severe or difficult-to-treat asthma who were followed semi-annually and annually for three years, enabling insight to be gained into this understudied population. A broad range of demographic, clinical, and patient self-reported assessments were completed during the follow-up period. Here, we present key findings from the TENOR registry in relation to asthma control and exacerbations, including the identification of specific subgroups found to be at particularly high-risk. Identification of the factors and subgroups associated with poor asthma control and increased risk of exacerbations can help physicians design individual asthma management, and improve asthma-related health outcomes for these patients.

Fig. 1

TENOR study design [•]. Adapted from Chipps et al. 2012 [•]; copyright (2012), with permission from Elsevier. Asterisk, daily high doses of inhaled steroids were defined by the American Thoracic Society refractory asthma guidelines for adults [37] and by the 1997 National Heart Lung and Blood Institute (NHLBI) guidelines for children [12]

Fig. 2

A) Odds of future exacerbations associated with recent exacerbations, B) Odds of future steroid burst associated with recent steroid bursts, adjusted for demographics, asthma severity, and asthma control [16]. Adapted from Miller et al. 2007 [16]; copyright (2007), with permission from Elsevier. Recent referred to the three months before baseline. Severe exacerbations was defined as either an asthma-related emergency department visit or hospitalization. X axis is on a logarithmic scale. ATAQ, asthma therapy assessment questionnaire; GINA, global initiative for asthma; NAEPP, national asthma education and prevention program

Fig. 3

Adjusted risk of acute asthma-related healthcare events by baseline level of asthma control [18]. Adapted from Sullivan et al. 2007 [18]. Asthma control was determined at baseline by use of The Asthma Therapy Assessment Questionnaire. ED, emergency department

Fig. 4

Risk of asthma exacerbations at the Month 30 visit associated with consistently very poorly controlled asthma, as defined by impairment domain of the NHLBI guidelines [•]. Adapted from Haselkorn et al. 2009 [•]; copyright (2009), with permission from Elsevier. Final adjusted models for hospitalization and ED visits include previous hospitalization or ED visits, number of long-term controllers, body mass index, allergic triggers, non-allergic triggers, percent predicted FVC, race or ethnicity, and age. Final adjusted models for corticosteroid courses include previous corticosteroid course, chronic obstructive pulmonary disease, non-allergic triggers, percent predicted FEV₁/FVC ratio, race or ethnicity, and age. CI, confidence interval; ED, emergency department; FEV ₁, forced expiratory volume in 1 second; FVC, forced vital capacity; NHLBI, National Heart Lung and Blood Institute