| (Ghilley, Bhadoria, & Pandit, 2018) | 120 patients | Descriptive correlational | NA | SGRQ-C | FEV1/FVC (%) ratio | Age, BMI, Smoke pack/year, GOLD stage |
| (Pati et al., 2018) | 110 patients | The parallel mixed-method study design was | Between June and July 2014 | SGRQ | Advanced age, Sex/female, More than two comorbidities, Low income, Family support | Occupation, Place of living |
| (Gaude & Desai, 2018) | 44 patients | Cross-sectional study | Between October 2016-November 2016 | SGRQ | NA | Age, Sex, Smoking, BMI, Socioeconomic status, Occupation type |
| (Farag, Sobh, Elsawy, & Fahmy, 2018) | 200 patients | A cross-sectional observational multicenter study | 2 years | Arabic version of SGRQ. | FEV1 % Predicted, New, GOLD stage (ABCD), Comorbidity, particularly IHD, mMRC, Frequency of exacerbations per year, 6MWD | Age, BMI, GOLD Spirometrics staging, BODE index, FEV1/FVC (%), Smoking pack/year |
| (Brandl et al., 2018) | 206 patients | A prospective patient cohort study | 1 year and 4 months | Short-Form (SF-12) Health Survey Questionnaire | CAT, Number of, exacerbations (years), FEV1 % Predicted, Living alone | Age, Female gender, High educational level, Smoking, Number of medications, Disease duration |
| (Lee et al., 2017) | 1264 patients | Prospective cohort | Between December 2011 and November 2015 | SGRQ-C | Age, Education, No of comorbidities, 6MWD, Depression level, mMRC | Sex, BMI, Smoking status, FEV1% predicted |
| (Das, Bam, & Ghimire, 2017) | 81 patients | Descriptive observational cross-sectional | 5 months | SGRQ-C | Smoking status | Age, Sex, Occupation, Education, Medications |
| (Cheruvu, Odhiambo, Mowls, Zullo, & Gudina, 2016) | 16602 patients | Telephone survey designed | From the 2011 and 2012 | A newly developed tool which contains four HRQOL indicators | Sex, Age, Current smoker | Activity limitation, Unmarried, Level of education less than a college degree |
| (Kwon & Kim, 2016) | 2734 patients | Cross-sectional survey study | Between 2007-2012 | EQ-5D | Age, Sex, Severity of COPD, Diabetes and hypertension comorbidities, Smoking status | Educational level, Income level |
| (Martinez et al., 2016) | 4097 participants in the COPD Gene study and 1522 participants in SPIROMICS | a cross-sectional analysis of data from participants with COPD in two cohorts | NA | SGRQ | Race, Smoking status, Moderate to severe dyspnea, exacerbation frequency, Presence of chronic bronchitis symptoms | Comorbidities, Activity level, Anxiety, and depression |
| (Sharma & Joshi, 2015) | 40 patients | A cross-sectional hospital-based study | From August 6, 2014, to August 7, 2014 | a 56-item QOL questionnaire developed by the researcher | Age, Current smoker, Education level, Comorbidities, Hospital no of admission last three months, Need of drugs regularly | Sex, Marital status, Place of residence, Family type, Work status, Economic status, Duration of COPD, Smoking status |
| (Hong et al., 2015) | 1178 patients | A cross-sectional survey analysis | Between the year of 2007 and 2010 | EQ-5D | Old age, female gender, lower education level, many comorbid diseases, severe airflow obstruction (Gold stage) | BMI, ever-smoking |
| (Ekici, Bulcun, Karakoc, Senturk, & Ekici, 2015) | 62 patients | Descriptive correlational | NA | SGRQ | FEV1 % Predicted, mMRC, Anxiety scores | Age, BMI, Total number of hospitalizations, Depression score |
| (Xiang et al., 2015) | 142 COPD outpatients and 218 controlled COPD | Case-control study | May 1, 2004, to April 30, 2005. | MOS-SF-12 SGRQ | Marital status, Education, Religious belief, Life event in the past year | COPD severity, Living with others, Age/year, Sex/male, No of comorbidities, No of hospitalization last year ADLs |