Clinical and Functional Heterogeneity of COPD Phenotypes: A Multicenter Study from Turkey (DIPTUR Study)

Background and Objectives: Chronic obstructive pulmonary disease (COPD) is heterogeneous, and phenotype-based classification may better capture differences in clinical burden and healthcare needs beyond standard GOLD categories. We aimed to describe the distribution of GesEPOC COPD phenotypes in Turkey and compare their demographic, clinical, functional, radiological, treatment, and healthcare utilization profiles. Materials and Methods: DIPTUR was a multicenter, observational, cross-sectional study conducted prospectively in 26 centers across 17 Turkish cities (October 2019-June 2021). Stable COPD patients (≥40 years; post-bronchodilator FEV1/FVC < 0.7) without exacerbation or major treatment modification within the previous four weeks were enrolled consecutively. Phenotypes were assigned per GesEPOC: exacerbator with emphysema (EE), exacerbator with chronic bronchitis (ECB), asthma-COPD overlap (ACO), and non-exacerbator (NE). Frequent exacerbators were defined as patients who experienced two or more exacerbations during the 12 months preceding enrollment, based on medical records and patient reports. Results: Among 894 patients, phenotype distribution was NE 44.1%, ECB 26.2%, EE 20.5%, and ACO 9.3%. Male predominance was observed across groups (80-89%; p = 0.006). Active smoking was most frequent in ECB (37.6%; p < 0.001), and BMI was lowest in EE (p < 0.001). Comorbidity patterns differed, with hypertension (p < 0.001), diabetes mellitus (p = 0.029), and heart failure (p < 0.001) most prevalent in ECB. Pulmonary function (FEV1 and FVC) was lowest in EE (both p < 0.001), and severe airflow limitation (GOLD III-IV) was most common in EE and ECB (p < 0.001). Dyspnea (mMRC ≥ 2) was more frequent in EE/ECB than in ACO/NE (p < 0.001). Emphysematous changes on thoracic CT predominated in EE (91.7%; p < 0.001). Long-term oxygen therapy was most common in EE (32.4%; p < 0.001). Emergency admissions, hospitalizations, and total length of stay were markedly higher in EE and ECB than in ACO and NE (all p < 0.001). Conclusions: COPD phenotypes in Turkey show substantial heterogeneity in clinical, functional, radiological, and utilization domains. Exacerbator phenotypes-particularly EE and ECB-represent higher-burden groups, supporting phenotype-oriented management and closer monitoring beyond GOLD classification.