Predictors of Asthma Severity in the Elderly: Results of a Community Survey in Northeast England

Abstract

A number of risk factors for the development and severity of asthma in childhood are known. Particularly, there is information on allergens, excessive use of β2- agonists, and indoor environmental pollutants. Similar information on elderly patients is lacking. We examined the risk factors for current asthma and for the severity of asthma in 95 elderly subjects (>65 years old) compared to 274 elderly subjects with obstructive spirometry who did not have asthma as defined by the following criteria: symptoms of episodic wheeze, cough, or chest tightness and forced expiratory volume in 1 sec/vital capacity (FEV1/VC) <70% with >15% or 200 ml. reversibility in FEV1 to 200 μg salbutamol given from a metered-dose inhaler. The severity of airflow limitation was graded on the basis of the FEV1/VC ratio as mild (60%-70%), moderate (40%-60%), and severe (<40%). Asthma history was collected using the Medical Research Council respiratory questionnaire and a follow-up postal questionnaire. Data were analyzed using multiple logistic regression and the overall goodness-of-fit of the model was checked using the Hosmer-Lemeshow (HL) statistic. History of allergy (to one or more of the following allergens: cat, house dust, or grass or tree pollen) (odds ratio [OR] 25; 95% confidence interval [CI] 13-51; p = 0.0001) and history of childhood wheeze (OR 8; 95% CI 4-9; p = 0.004) were strong predictors of current asthma. Duration of wheezing, smoking history, indoor heating, history of working in coal mines, and sex were not predictors (HL 6.75, degrees of freedom [df] = 8, p = 0.56). Use of >4 puffs of salbutamol/day (OR 5.3; 95% CI 2-14; p = 0.005), more than 10 years of asthma symptoms (OR 4.2; 95% CI 4.1-36.2; p = 0.0001), and >500 mL reversibility in FEV, (OR 4.2; 95% CI 1.2-14.3; p = 0.05) were independent predictors of moderate to severe asthma. History of atopy was the strongest predictor of asthma in the elderly population studied. Indoor heating, presence of pets at home, sex, smoking history, and history of working in coal mines were not predictors of asthma. The severity of asthma as assessed by measurement of airflow limitation was related to the frequency of use of β2-agonists, duration of symptoms of asthma, and increased reversibility of FEV1 to β2-agonist.