Level of physical (in)activity in adults with asthma: assessment of predictive factors and effects of behavioral interventions to increase physical activity on the asthma clinical control

Abstract

Background: It is estimated that physical inactivity is a major risk factor for the increase in chronic non-communicable diseases' prevalence and that habitual physical activity appears to have an important protective role. Recent studies have shown controversial results regarding the impact of asthma on the daily-life physical activity (DLPA) and the effect of behavioral interventions on the DLPA and its impact on improving clinical asthma control remains unknown. Objectives: the study has two objectives: i) to assess the level of DLPA and their possible predictors factors between adult asthmatics and non-asthmatics control, ii) to analyze the effects of behavioral interventions to increase physical activity on the asthma clinical control. Methods: The study will be performed in 2 phases and the sample will be composed of 160 asthmatics and non-asthmatics adults, from both genders and aged between 20 to 59 years. In Phase I, patients will be submitted to the DLPA assessment (by accelerometry), anthropometric and body composition measurements, assessment of barriers to DLPA, asthma exacerbations and lung function. Asthmatic patients will also be also asked to fill out the ACQ (Asthma Control Questionnaire), the AQLQ (Asthma Quality of Life Questionnaire) and the HADs (Hospital Anxiety and Depression scale). The control group (non-asthmatic individuals) will be matched with asthmatic patients regarding anthropometric measurements (age, gender and BMI) and will consist of friends and relatives of asthmatics without asthma symptoms, measured by ISAAC (International Study of Asthma and Allergies in Childhood, validated for adult). The phase 2 will be a Randomized Controlled Trial (RCT) composed by, at least 46 patients from phase I with uncontrolled asthma and physically inactive (<7,500 steps/day). They will be randomly assigned to either Control Group (CG) or Intervention Group (IG), where only patients from IG will be submitted to a behavioral intervention through counseling and incentives to increase the DLPA. The levels of DLPA, asthma clinical control, quality of life, body composition and asthma exacerbations will be assessed before and after the intervention, using the same tools of phase I. The comparison of continuous and categorical variables will be performed using t-test or Man-Whitney and chi square test, respectively. P Predictors factors of DLPA in asthmatics will be analyzed by multivariate linear regression (stepwise) and treatment-by-time interactions by a two-way repeated-measures ANOVA followed by the Bonferroni post-hoc test. The analysis of the difference between the proportion of individuals with improvement in clinical variables will be performed via a Ç2 test. The significance level will be set at 5% (p<0.05).