Quantifying Asthma Symptoms in Adults

BACKGROUND: Accurate assessment of asthma symptoms is critical in research and clinical settings. A multidimensional asthma control questionnaire could provide more accurate information about asthma symptoms than global assessments, which often overestimate asthma control. OBJECTIVE: The authors sought to evaluate the efficacy of the Lara Asthma Symptom Scale (LASS) in adults with persistent asthma. METHODS: Participants were 18 to 64 years of age with persistent asthma. Data were collected at baseline, 6 months, and 12 months. The authors described the construct and predictive validity of the LASS by comparing it with measures of pulmonary function (FEV(1)), asthma-specific quality of life (Juniper's Asthma Quality of Life Questionnaire [AQLQ]), and health care use (emergency department [ED] visits and hospitalizations). RESULTS: Three hundred eighty-three participants provided baseline data. The LASS had high internal consistency reliability (Cronbach alpha = .84). LASS scores correlated significantly with baseline measures of FEV(1) (-0.20, P = .0002), AQLQ (-0.68, P < .0001), ED visits (0.17, P = .002), and hospitalizations (0.15, P = .008). Baseline LASS scores were associated significantly with ED visits (P = .03) and hospitalizations (P = .04) over the subsequent 12 months. Change in LASS scores over time correlated significantly with changes in FEV(1) (-0.22, P = .001) and AQLQ (-0.70, P < .001). CONCLUSIONS: The LASS demonstrated good internal consistency, excellent validity based on concurrent criterion validity and longitudinal predictive validity, and good discriminatory properties in a heterogeneous sample of adults with persistent asthma. CLINICAL IMPLICATIONS: This study validates a simple multidimensional asthma questionnaire as a clinical tool in the assessment of asthma control in adults.