| First author [ref.] | Assessment tools | Patients | Prevalence of depression % |
| De [22] | PHQ-9 | 100 consecutively recruited Indian patients with stable COPD | 72 |
| Hayashi [23] | HADS-D | 80 outpatients and 51 inpatients suffering from stable COPD in Japan | 40.5 |
| Goodwin [24] | CIDI diagnosis of major depression | 147 COPD patients (self report) in the USA | 24.8 |
| Joo [25] | Standardised questionnaires on comorbidities associated with COPD | 354 COPD patients (subsample of 9744 subjects from the Korean population) | COPD: 18.7; non-COPD: 17.4 |
| Loerbroks [26] | GDS-15 sum score ≥4 points | 7995 COPD patients from a large population sample from southern China | 22.9 |
| Lou [27] | HADS-D ≥8 points | 1100 outpatients with COPD from China and 1100 healthy controls | COPD: 35.7; controls: 7.2 |
| Marinho [28] | GDS-15 | 40 elderly COPD patients from Brazil | 22.5 |
| Obradovic [29] | HDRS | 40 COPD patients from Serbia | 20.0 |
| Schnell [30] | Physicians’ lifetime diagnosis of depression | 995 COPD patients (aged ≥45 years) from the USA | 20.6 |
| Arimura [31] | CES-D score ≥10 points | 52 consecutively recruited and clinically stable COPD patients in the pulmonary departments of five hospitals in Japan | 29 |
| Horita [32] | SF-GDS ≥6 points | 84 consecutive, stable COPD outpatients in a Japanese community hospital | 38.1 |
| Iguchi [33] | Japanese version of the CES-D sum score ≥16 points | 74 COPD patients from long-term Japanese inpatient rehabilitation facilities | 48.6 |
| Lee [34] | PHQ-9 ≥10 points | 803 COPD inpatients from Korea | 23.8 |
| Papaioannou [35] | BDI-I sum score ≥19 points | 230 consecutive COPD inpatients in departments of respiratory medicine in two tertiary hospitals in Greece | 39.6 |
| Qian [36] | Clinical ICD-9-CM diagnoses of depressive disorders | 75 699 US beneficiaries# (minimum age 65 years) with a diagnosis of COPD | 21.6 |
| Sharma [37] | Global Mental Health Assessment Tool – Primary Care and General Health version | 52 consecutive patients with stable COPD attending a respiratory disease clinic in Northern India | COPD: 19.2; controls: 3.4 |
| Warmenhoven [38] | General practitioners’ lifetime diagnosis of depressive disorders | 982 Dutch patients with COPD, cardiovascular disease and cancer in the last phase of their lives | 8.2 |
| Zhang [39] | Face-to-face questionnaire | 7597 COPD patients from China | 28.3 |
PHQ-9: patient health questionnaire-9; HADS-D: hospital anxiety and depression scale depression subscale; CIDI: composite international diagnostic interview; GDS-15: geriatric depression scale 15-item version; HDRS: Hamilton depression rating scale; CES-D: Center for Epidemiologic Studies depression scale; SF-GDS: short-form geriatric depression scale; BDI-I: Beck’s depression inventory I; ICD-9-CM: international classification of diseases, 9th revision, clinical modification. #: persons enrolled in Medicare parts A, B and D in the USA.