Of the total 2010 US NHWS respondents (n = 75,000) the mean age was 48.17 ± 16.53 years. In total, 48.22% were male, 38.37% were employed full-time, 19.09% were current smokers, 45.15% had a 2009 household income < $50,000, and 58.92% had less than a college degree.
Of patients reporting only one diagnosis, most patients reported being diagnosed with chronic bronchitis (n = 2071; 60.20%), followed by COPD (n = 970; 28.20%) and emphysema (n = 399; 11.60%). Patients with chronic bronchitis were significantly more likely to be female (63.21% versus 42.37% for COPD versus 37.84% for emphysema, P < 0.05) and nonwhite (20.76% versus 10.72% for COPD versus 13.28% for emphysema, P < 0.05) relative to those with COPD and emphysema (). Patients with chronic bronchitis were also significantly younger relative to those with COPD and emphysema (51.38 years versus 63.24 years for COPD versus 63.30 years for emphysema, P < 0.05) and more likely to be currently employed (46.98% versus 23.81% for COPD versus 28.33% for emphysema, P < 0.05). Patients with chronic bronchitis also had the least comorbidity burden (Charlson comorbidity index 1.70 versus 2.00 for COPD versus 1.82 for emphysema, P < 0.05), were significantly less likely to be a current or former smoker and more likely to exercise (56.74% versus 43.40% for COPD versus 42.11% for emphysema, P < 0.05) relative to the other COPD phenotypes ().
Patient characteristics and self-reported health behaviors among COPD phenotypes
Those with chronic bronchitis have been diagnosed with their condition the longest (16.23 years versus 7.57 years for COPD versus 9.39 for emphysema, P < 0.05) and were the least likely to report the severity of their condition as “moderate” or “severe” relative to patients with COPD or emphysema (65.38% for mild versus 42.47% for COPD versus 49.87% for emphysema, P < 0.05, ). The most frequent symptoms experienced by patients with COPD were dyspnea (mean 3.74 for COPD versus 3.59 for emphysema versus 2.95 for chronic bronchitis, P < 0.05), wheezing (mean 2.97 for COPD versus 2.71 for emphysema versus 2.76 for chronic bronchitis, P < 0.05), and mucus production (mean 2.97 for COPD versus 2.86 for emphysema versus 3.05 for chronic bronchitis, P < 0.05). Patients with emphysema reported a symptom profile similar to that of patients with COPD, but all symptoms were less frequent, albeit not all significantly so. Patients with chronic bronchitis reported the most frequent mucus production, coughing (mean 2.83 for chronic bronchitis versus 2.78 for COPD versus 2.65 for emphysema, P < 0.05), and infections (mean 2.31 for chronic bronchitis versus 1.99 for COPD versus 1.78 for emphysema, P < 0.05) relative to the other phenotypes. The main causes of a COPD/emphysema/chronic bronchitis episode were smoking (58.56% for COPD versus 67.67% for emphysema versus 31.87% for chronic bronchitis, P < 0.05), illnesses, eg, colds and influenza (24.33% for COPD versus 14.79% for emphysema versus 50.27% for chronic bronchitis, P < 0.05), allergies/allergic reactions (21.13% for COPD versus 18.30% for emphysema versus 46.40% for chronic bronchitis, P < 0.05), weather/temperature (30.52% for COPD versus 26.82% for emphysema versus 36.41% for chronic bronchitis, P < 0.05), pollutants/airborne irritants (25.26% for COPD versus 19.05% for emphysema versus 27.23% for chronic bronchitis, P < 0.05), exercise/physical activity (30.41% for COPD versus 27.57% for emphysema versus 19.12% for chronic bronchitis, P < 0.05), and occupational hazards, eg, paint fumes and car exhaust (18.25% for COPD versus 13.03% for emphysema versus 10.96% for chronic bronchitis, P < 0.05).
Disease characteristics and medications used by COPD phenotypes
The number of patients across all phenotypes who remained untreated varied significantly (24.95% for COPD versus 47.12% for emphysema versus 71.75% for chronic bronchitis, P < 0.05). Short-acting beta-agonist (SABA) use was the most common monotherapy for all phenotypes, but significantly (P < 0.05) more for patients with chronic bronchitis (33.54% versus 11.22% for emphysema versus 12.92% for COPD). Patients with chronic bronchitis were also significantly more likely to use inhaled corticosteroids (ICS) + a long-acting beta agonist (LABA, 13.62%) and ICS + LABA + SABA (19.31%) therapies (P < 0.05). Conversely, triple therapy (ICS + LABA + long-acting or short-acting muscarinic antagonist) was significantly more infrequent for patients with chronic bronchitis whether it was with a SABA (6.30% versus 16.84% for COPD versus 21.46% for emphysema, P < 0.05) or without a SABA (1.02% versus 8.42% for COPD versus 11.22% for emphysema, P < 0.05).
Despite reporting the lowest level of mental component summary scores (chronic bronchitis 43.98 versus 46.95 for COPD versus 48.62 for emphysema, P < 0.05), patients with chronic bronchitis reported the highest levels of physical component summary scores (41.43 for chronic bronchitis versus 34.88 for COPD versus 37.59 for emphysema, P < 0.05), the lowest activity impairment (42.15% for chronic bronchitis versus 50.36% for COPD versus 42.88% for emphysema, P < 0.05), and the fewest hospitalizations (0.22 for chronic bronchitis versus 0.30 for COPD versus 0.30 for emphysema, P < 0.05, ). Patients with COPD reported the lowest physical component summary scores, and the highest levels of activity impairment, hospitalizations, and physician visits (P < 0.05). Patients with emphysema had a worse physical component summary score and more hospitalizations than those with chronic bronchitis. No differences were observed among the phenotypes in terms of work productivity losses or number of emergency room visits.
Unadjusted health outcome differences among COPD phenotypes
Adjusting for demographics and health characteristics, patients with COPD reported the lowest mean physical component summary scores (36.69) and health utilities (0.65) relative to other phenotypes (). Patients with COPD also reported the highest level of work impairment. With the exception of absenteeism, where there were no differences between patients with COPD (7.1%) and chronic bronchitis (5.6%), both were higher than for patients with emphysema (3.0%). Patients with COPD reported greater levels of work and activity impairment relative to those with chronic bronchitis and those with emphysema (). No significant differences were observed between the groups with respect to resource utilization.
Adjusted differences on physical and mental component summary scores among COPD phenotypes.
Adjusted differences on work productivity and activity impairment among COPD phenotypes.