Although COPD is associated with significant health-related quality-of-life (HRQL) impairment, factors influencing HRQL in patients with COPD are not well understood, particularly in African Americans. We hypothesized that HRQL in COPD differs by race and sought to identify factors associated with those differences.
We analyzed 224 African American and 1,049 Caucasian subjects with COPD enrolled in the COPDGene (Genetic Epidemiology of COPD) Study whose conditions were classified as GOLD (Global Initiative for Chronic Obstructive Lung Disease) stages I to IV. HRQL and symptoms were compared using the St. George Respiratory Questionnaire (SGRQ) and the modified Medical Research Council Dyspnea (MMRC) scale. We constructed a mixed-effects linear regression model for SGRQ score.
African Americans were younger and reported fewer pack-years of smoking, more current smoking, and less attained education than Caucasians; MMRC scores were higher (P = .02) as were SGRQ scores (mean score difference, 8.4; P < .001). In a general linear model of SGRQ total score after adjusting for factors such as age, sex, and pack-years of smoking, SGRQ total score was similar for African Americans and Caucasians who reported no COPD exacerbations in the prior year. However, for subjects with exacerbations, SGRQ total score was increased to a greater relative extent for African Americans than for Caucasians (1.89 points for each exacerbation, P = .006). For hospitalized exacerbations, the effect on SGRQ total score also was greater for African Americans (4.19 points, P = .04). Furthermore, a larger percentage of African Americans reported having had at least one exacerbation that required hospitalization in the prior year (32% vs 16%, P < .001).
In analyses that account for other variables that affect quality of life, HRQL is similar for African Americans and Caucasians with COPD without exacerbations but worse for African Americans who experience exacerbations, particularly hospitalized exacerbations.
ClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov