Criteria and scoring system for assessment of study methodology
| Criterion | Score |
|---|---|
| Random selection of patients | 1 |
| Control group matched for age and sex | 2 |
| Response rate >80% | 1 |
| Prevalence of depressive disorder detectable | 1 |
| Exclusion of important physical disease other than COPD | 1 |
| Maximum score | 6 |