Poor asthma control and exposure to traffic pollutants and obesity in older adults

Abstract

Background: Environmental and host predictors of asthma control in older asthmatic patients (>65 years old) are poorly understood.

Objective: To examine the effects of residential exposure to traffic exhaust and other environmental and host predictors on asthma control in older adults.

Methods: One hundred four asthmatic patients 65 years of age or older from allergy and pulmonary clinics in greater Cincinnati, Ohio, completed the validated Asthma Control Questionnaire (ACQ), pulmonary function testing, and skin prick testing to 10 common aeroallergens. Patients had a physician's diagnosis of asthma, had significant reversibility in forced expiratory volume in 1 second or a positive methacholine challenge test result, and did not have chronic obstructive pulmonary disease. The mean daily residential exposure to elemental carbon attributable to traffic (ECAT) was estimated using a land-use regression model. Regression models were used to evaluate associations among independent variables, ACQ scores, and the number of asthma exacerbations, defined as acute worsening of asthma symptoms requiring prednisone use, in the past year.

Results: In the adjusted model, mean daily residential exposure to ECAT greater than 0.39 μg/m(3) was significantly associated with poorer asthma control based on ACQ scores (adjusted β = 2.85; 95% confidence interval [CI], 0.58-5.12; P = .02). High ECAT levels were also significantly associated with increased risk of asthma exacerbations (adjusted odds ratio, 3.24; 95% CI, 1.01-10.37; P = .05). A significant association was found between higher body mass index and worse ACQ scores (adjusted β = 1.15; 95% CI, 0.53-1.76; P < .001). Atopic patients (skin prick test positive) had significantly better ACQ scores than nonatopic patients (adjusted β = -0.39; 95% CI, -0.67 to -0.11; P < .01).

Conclusion: Higher mean daily residential exposure to traffic exhaust, obesity, and nonatopic status are associated with poorer asthma control among older asthmatic patients.

Fig. 1

Map of elemental carbon attributable to traffic (ECAT) estimates based on residential addresses for 104 asthmatic patients 65 years or older from Cincinnati, Ohio. Larger, darker circles indicate ECAT concentrations of 0.39 to 0.63 µg/m³; smaller, lighter circles represent ECAT concentrations of 0.23 to 0.38 µg/m³. Thin, dark lines represent interstates or highways. The thick blue line is the Ohio river and county lines are gray.