Predictors of health status do not change over three-year periods and exacerbation makes difference in chronic obstructive pulmonary disease

BACKGROUND: The association between disease markers and health status (HS) overtime is unclear. The aim of this study was to verify the predictors of HS at baseline and after three years in Chronic Obstructive Pulmonary Disease (COPD) patients. METHODS: Ninety-five consecutive COPD patients (66% male, age = 67 ± 9 y, FEV(1 )= 58 ± 23%) underwent the following evaluations at baseline and after three years: body composition, pulse oximetry (SpO(2)), six-minute walk distance (6MWD), Modified edical Research Council dyspnea scale (MMRC) and Saint George's Respiratory Questionnaire (SGRQ). The Charlson comorbidity index and BODE index were calculated. COPD exacerbations during the follow-up were evaluated. At baseline, age, gender, smoking, SpO(2), BODE index or its components (BMI, MMRC, FEV(1 )and 6MWD), and Charlson index were included in a multiple linear regression analysis with the baseline SGRQ total score as the dependent variable. After three years, we included the final values of the variables plus the number of exacerbations and the final SGRQ total score as the dependent variable. RESULTS: SGRQ total score (42 ± 19% vs 44 ± 19%; p = 0.041) and activity domain (52 ± 21% vs 60 ± 22%; p < 0.001) deteriorated during follow-up. At baseline, BODE index was selected as a predictor of SGRQ total score (R(2 )= 0.46; p < 0.001); after three years, BODE index and age were the predictors (R(2 )= 0.49; p < 0.001). When the BODE index was replaced by its variables, MMRC was selected as the only variable associated with the SGRQ total score (R(2 )= 0.58; p < 0.001). After three years, MMRC, FEV(1 )and number of exacerbations were selected as predictors of SGRQ total score (R(2 )= 0.63; p < 0.001). CONCLUSION: HS deteriorated significantly over the three-year period and the predictors of HS do not change over time. BODE index and dyspnea were predictors at baseline and after three years. Exacerbation was also a predictor of HS after three years. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00605540