Rationale: The Undiagnosed COPD and Asthma Population trial showed that early diagnosis and treatment of asthma and chronic obstructive pulmonary disease (COPD) by pulmonologists improved healthcare use, respiratory symptoms, and quality of life. Objectives: To determine if the benefits of early diagnosis and treatment were greater in individuals with more advanced disease or in individuals with asthma as opposed to COPD. We also assessed whether pulmonologist-directed care benefited asthma and COPD subgroups equally. Methods: Case finding was used to identify adults with undiagnosed chronic respiratory symptoms in the community. A total of 508 newly diagnosed participants with COPD or asthma were randomized to receive pulmonologist-care intervention or usual care. Low and high disease burden categories for the St. George's Respiratory Questionnaire (SGRQ) and COPD Assessment Test were defined using a median-split of baseline scores, and minimal clinically important difference thresholds were used to define significant responses. Benefits of pulmonologist care were assessed by evaluating treatment effects within subgroups and by assessing treatment-by-subgroup interactions. Measurements and Main Results: Patients with higher disease burden at diagnosis were more likely to benefit from early diagnosis and treatment compared with those with lower disease burden. A total of 71% of those with high disease burden showed an improvement in COPD Assessment Test score by ⩾2 points over 12 months compared with 47% with low disease burden (odds ratio, 2.78; 95% confidence interval, 1.90-4.07; P < 0.001). Similar results were seen for SGRQ and FEV1 improvements. In contrast, responses to early diagnosis and treatment were similar for those with asthma versus COPD. Individuals with asthma randomized to undergo pulmonologist-directed care showed greater 1-year improvements in COPD Assessment Test score, SGRQ score, 36-item Short Form score, and FEV1 compared with individuals randomized to receive primary care. However, individuals with COPD experienced similar improvements regardless of whether their treatment was managed by a pulmonologist or primary care provider. Treatment-by-disease interaction terms were not statistically significant. Conclusions: Patients with greater disease burden who exhibited more advanced and symptomatic asthma and COPD at the time of diagnosis benefited more from earlier diagnosis and treatment. Patients with asthma tended to derive greater benefit from pulmonologist-directed care than patients with COPD.
Keywords: COPD; asthma; case-finding; disease burden; early diagnosis.