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A6396 - Prevalence and Mechanism of Clinical Symptoms in Smokers with Preserved Pulmonary Function
Author Block: D. Chandra1, T. Nyunoya2, J. M. Bon3, C. Karoleski1, C. Riley4, F. C. Sciurba5; 1Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, United States, 2Medicine, University of Pittsburgh, Pittsburgh, PA, United States, 3Univ of Pittsburgh, Pittsburgh, PA, United States, 4UPMC, Pittsburgh, PA, United States, 5Univ of Pittsburgh Med Ctr, Pittsburgh, PA, United States.
RATIONALE: A recent publication from a research based cohort identified a 50% prevalence of symptoms (CAT score >10) in smokers with preserved pulmonary function. This group exhibited exercise impairment and evidence of radiographic airways thickening. We attempted to validate these findings in a separate cohort and to identify potential mechanism associated with the clinical symptoms despite normal spirometric function. METHODS: Of 237 subjects in the Pittsburgh tobacco exposed SCCOR cohort (largely derived from a community based rather than clinical based recruitment strategy) 30 had preserved spirometry defined as an FEV1/FVC > 0.7 and FVC > LLN. We used the Saint George’s Respiratory Questionnaire (SGRQ) score of ≥25 as the cutoff to define a symptomatic subject, which has been shown to approximately correspond to a CAT score of ≥ 10. Symptomatic subjects were compared to asymptomatic subjects with respect to measures of spirometry, air trapping based on plethysmographic lung volumes, Beck Depression Index (BDI), Quantitative CT measures of emphysema (f-950) and airway wall thickness (WA%), endurance shuttle walk, single breath CO diffusing capacity (DLCO), BMI, Coronary Artery Calcification score (CAC), and pulmonary artery enlargement (PA/a ratio). RESULTS: Based on an SGRQ ≥25, n =30 (12.7%) of subjects with preserved lung function were symptomatic. Subjects with symptoms had a higher Beck Depression score 10.3 ± 1.2 compared to those who are asymptomatic 5.0±0.3 (p =0.0001). This was reflected in a more frequent use of antidepressants in symptomatic 10/30 33.3% compared to asymptomatic 41/207 19.8% (p =0.10). Symptomatic individuals had a significantly lower walk distance 392±31 compared to asymptomatic 473±9 feet. However, there were no significant differences between groups with respect to age, FEV1, Residual Volume, Total Lung Capacity, f-950, WA%, DLCO, BMI, CAC or PA/a ratio. CONCLUSIONS: Symptomatic smokers with preserved lung function may be significantly less prevalent than previously reported, and the prevalence may be dependent on the method of cohort recruitment. Symptomatic subjects in our cohort had significantly higher Beck depression scores and more frequent use of antidepressants. While symptomatic patients had poorer exercise tolerance than asymptomatic subjects, we could not identify differences in objective measures of spirometric or plethysmographic lung function, quantitative airway measures or cardiac or pulmonary comorbidity to explain the differences in symptoms.