Table 3. Predictive Factors Assessed in COPD Epidemiological Studies.

Study Design and Setting								Factors/Predictors
Study Author	Titlea	Year	Study Designb	Country	Population	Sample Size	Age Range Inclusion	Age	Gender	Race	BMI	Smoking	Passive Smoke, Exposure to Smoke, Second Hand Smoke	Primary Care Visits	Respiratory symptoms	Cough	Phlegm/Sputum	Dyspnea or Shortness of Breath	Wheeze	Chest Infectionsc	Prior Diagnosisd	Exposures (Dust; Biomass Fuel)	Childhood Illness	Education/Occupation	Health Status	Fatigue/Tiredness	Allergies	Breathing Medication or Antibiotics	Family History of Lung Disease	Income	Cardiac Co-Morbidity
de Marco36	Incidence of chronic obstructive pulmonary disease in a cohort of young adults according to the presence of chronic cough and phlegm	2007	Prospective study of COPD (incidence of COPD)	12 European countries	General population	5002	20–44	X	X			X				X	X	X						X
Hvidsten37	Prevalence and predictors of undiagnosed chronic obstructive pulmonary disease in a Norwegian adult general population	2010	Prospective study of COPD	Norway	General population	3506	47–48 and 71–73	X	X		X	X			X	X		X	X	X				X	X					X	X
Lamprecht38	COPD in never smokers: results from the population-based burden of obstructive lung disease study	2011	Prospective analysis	14 countries	General population	Men (n=1311)Women (n=2578)	≥40	X			X		X								X	X	X	X							X
Medbø39	What role may symptoms play in the diagnosis of airflow limitation?e	2008	Prospective study of COPDf	Norway	General population	3919	≥60	X	X			X				X	X	X	X
Ohar40	Do symptoms predict COPD in smokers?g	2010	Prospective study of COPD	US	General population	3955	≥40					X				X	X	X	X
Ulrik41	Early detection of COPD in general practice	2011	Prospective study of COPD	Denmark	General population	3095	>35	X	X		X	X
Albers42	Do family physicians records fit guideline diagnosed COPD?h	2009	Retrospective studyi	Netherlands	Primary care	532	20–70	X	X			X		X		X	X	X
Hill43	Prevalence and underdiagnosis of chronic obstructive pulmonary disease among patients at risk in primary care	2010	Prospective study of COPD	Ontario, Canada	Primary care	1003	≥40	X	X	X		X		X	X
Løkke44	Detection of previously undiagnosed cases of COPD in a high-risk population identified in general practice	2012	Prospective study of COPD	Denmark	Primary Care	4049	>35	X	X		X	X				X	X	X	X	X
Minas45	COPD prevalence and the differences between newly and previously diagnosed COPD patients in a spirometry program	2010	Prospective study of COPD	Greece	Primary care	1526	>30	X	X		X	X				X	X	X	X			X	X	X				X
Van Schayck46	Detecting patients at a high risk of developing chronic obstructive pulmonary disease in general practice: cross sectional case finding studyj	2002	Prospective study	Netherlands	Primary care	651	35–70									X		X	X		X					X	X		X
Vandevoorde47	Early detection of COPD: A case finding study in general practice	2007	Prospective study of COPD	Netherlands	Primary care	146	40–70	X	X			X				X		X	X		X	X				X

^aCOPD case definition unless otherwise noted was defined as postbronchodialator FEV₁/FVC ratio <0.70

^bMultivariate analysis used to assess significance in all studies unless otherwise noted

^cChest infections including cough, colds, respiratory issues that bring to the doctor

^dPrior diagnosis of asthma, bronchitis, or chronic expectorations

^eCOPD case definition: Pre bronchodilator FEV₁/FVC<0.70 for subjects 69 years and younger and pre bronchodilator FEV₁/FVC<0.65 for subjects 70 years and older

^fBinary logistic regression was used in calculating odds ratios

^gCOPD case definition: Post bronchodilator FEV₁/FVC<70%, aged ≥40, and ≥20 pack-years of smoking

^hCOPD case definition: No FEV₁ reversibility ≥12% and ≥200 ml after taking salbutamol

ⁱData source: DMCA, Detection, Intervention and Monitoring of COPD and Asthma

^jCOPD case definition: FEV₁<80%

Grey shading = odds ratio was significant at p<0.05