TABLE 2

Characteristics of 47 included systematic reviews for COPD, ranked by Joanna Briggs Institute (JBI) score

AuthorsRisk factor(s)Main findingsJBI score
Duan et al. [50]Early life exposuresChildhood respiratory disease, maltreatment, maternal smoking and low birth weight increase the risk of COPD development.11
Parvizian et al. [51]Unhealthy dietary patternsUnhealthy dietary patterns seemed to be associated with a higher risk of COPD; however, the meta-analysis was not statistically significant. Healthy dietary patterns were associated with a reduced risk.11
Asamoah-Boaheng et al. [52]History of asthmaIndividuals with a previous history of asthma were found to have an increasing likelihood of developing COPD in later life.11
Su et al. [53]Inflammatory markersThe findings suggested that COPD was associated with elevated serum CRP, leukocytes, IL-6, IL-8 and fibrinogen, without any significant relationship with TNF-α.11
Awokola et al. [54]Age, biomass exposure, smokingAn increased prevalence of COPD was associated with increasing age, smoking and biomass smoke exposure.10
Kamal et al. [55]SmokingThe results suggest a positive association between current smokers and the prevalence of COPD compared with former and nonsmokers.10
Sadhra et al. [56]Occupational dust exposureOverall occupational exposure to airborne pollutants as assessed by JEMs reported an increased risk of COPD.10
Yang et al. [57]Wide range investigating risk factors12 risk factors were found to be associated with the occurrence of COPD on the Chinese mainland: male sex, smoking, low education level, low BMI, family history of respiratory disease, allergy history, respiratory infection during childhood, recurrent respiratory infection, occupational dust exposure, biomass burning, poor housing ventilation and living around polluted areas.10
Peng et al. [58]Occupational dust exposureBeing exposed to occupational dust was found to increase COPD risk.10
Xiong et al. [59]High altitudeThe meta-analysis found a higher prevalence of COPD at high altitudes.10
Park et al. [60]PM2.5, PM10, NO2Both higher PM2.5 and NO2 levels were shown to increase risk of COPD. No association was found for PM10.10
Njoku et al. [61]Wide rangeSmoking, previous tuberculosis, use of biomass fuels, older age, wheeze and asthma were associated with increased COPD risk.9
Gershon et al. [62]Low SESThe study found consistent inverse associations between SES and COPD prevalence.9
Zheng et al. [63]Dietary patternsAn increase in the risk of COPD development was shown for the highest compared with the lowest categories of “unhealthy/Western-style” dietary patterns.9
Ryu et al. [64]Exposure to VGDFsThe study suggests that exposure to VGDFs is associated with a higher risk of COPD development.9
Li et al. [65]Parental COPDThe prevalence of COPD in adult offspring of people with COPD is greater than population-based estimates, showing that parental COPD is associated with COPD development in offspring.9
Borup et al. [66]Construction dustThe review suggests that COPD occurs more often among construction workers than among workers who are not exposed to construction dust.9
Guillien et al. [67]Agricultural workThe meta-analysis reported that cattle farming, swine farming and poultry farming are strongly associated with airflow limitation and chronic bronchitis. However, the results were inconsistent9
Ma et al. [68]Childhood wheezingThe results suggest an association between childhood wheezing and an increased risk of COPD.9
Kamal et al. [69]Indoor biomass burningThe meta-data analysis has shown that household air pollutants may be a factor associated with increased risk of COPD in women.9
Sutradhar et al. [70]All risk factorsTobacco consumption, exposure to biomass fuel, old age and history of asthma were identified as major risk factors for COPD development.9
Vinnikov et al. [71]Occupational exposure to VGDFsThe study reported occupational exposure to VGDFs increased the risk of COPD.9
Chen et al. [72]Wide rangePM exposure, smoking history, passive smoking history, sex, exposure to biomass burning, childhood respiratory infections and family history were found to be risk factors for COPD in the Chinese population8
van Iersel et al. [73]NutritionA high dietary intake of red and/or processed meats, refined grains, sweets, desserts and French fries are associated with an increased risk of COPD.8
Zhang et al. [74]BMIThe study reported underweight might increase the risk of COPD development, where being overweight might reduce the risk.8
Gan et al. [75]Age in female adult smokersAs female smokers age, they appear to be at higher risk of developing COPD when compared to male smokers.8
Finney et al. [76]Exploration of risk factorsThe current study identified biomass burning and smoking as risk factors for COPD development.8
Zhu et al. [77]Tobacco exposure, biomass fuel/solid fuel usage, gender, age, low BMI, family history, history of respiratory disease, occupational dust exposure, low education levelThe study found all aforementioned risk factors to be important risk factors for COPD development.8
Salari-Moghaddam et al. [78]Processed red meat intakeThe meta-analysis found a positive association between processed red meat intake and risk of COPD development.8
Bellou et al. [79]Environmental risk factorsThe review showed that active and passive smoking, exposure to biomass fuels, history of tuberculosis and history of rheumatoid arthritis were associated with COPD.7
Ali [80]Childhood asthmaChildren with asthma were found to be at risk of developing COPD later in life.7
Pathak et al. [81]Indoor air pollution from biomass cooking fuelExposure to indoor air pollution due to solid biomass fuels was associated with an increased risk of COPD.7
Zhang et al. [82]Exposure to nitrogen dioxideThe study found consistent evidence of the positive association between NO2 exposure and COPD risk.7
Kurmi et al. [83]Indoor air pollution from solid fuelExposure to solid fuel smoke was found to be consistently associated with COPD development.7
Doust et al. [46]Pesticide exposureThere was weak evidence for an association between pesticide exposure and increased likelihood of COPD.7
Brüske et al. [84]Bio persistent granular dustExposure to impersistent granular dust was associated with COPD development.7
Baur et al. [44]Workplace irritantsThere is evidence that long-term exposure to workplace irritants could increase COPD development.7
Adeloye et al. [85]Wide rangeMale sex, age, smoking status, second-hand tobacco smoke, biomass exposure, occupational exposure to dust or smoke, BMI, previous respiratory illness, SES, education level and area of living were associated with COPD.6
Budhathoki et al. [86]Smoking and traditional firewood cookingSmoking and traditional firewood cooking were identified as major risk factors for COPD6
Lee et al. [87]Cigarette smokingAn increased risk of COPD development with current smoking and a lesser increase with ex-smoking was found.6
Fontana et al. [88]Agricultural workThe review found farming work to be associated with a greater risk of developing COPD.6
Wang et al. [89]SmokingRisk of COPD for ever-smokers is higher than the risk of COPD development in never-smokers.6
Forey et al. [90]SmokingThe risk of male smokers seems to be higher than female smokers, as well as the risk of cigarette smoking as compared to smoking other products.6
Chaudhary et al. [91]Elevated serum homocysteineElevated serum homocysteine was found to contribute to risk of COPD development.6
Lee et al. [92] ETSThe evidence suggests that exposure to ETS is a risk factor for COPD development.6
Cunalata-Paredes et al. [93]Wide rangeThe study found associations with second-hand smoking, male sex, older age, biomass exposure, asthma, respiratory problems in childhood and tuberculosis and COPD development.5
Pando-Sandoval et al. [94]Wide range in never-smokersIncreased COPD risk was associated with exposure to biomass, occupational exposure and passive smoking to having a history of asthma, tuberculosis or respiratory infections during childhood.5

BMI: body mass index; CRP: c-reactive protein; ETS: environmental tobacco smoke; IL: interleukin; PM: particulate matter; JEM: job exposure matrix; SES: socioeconomic status; TNF-α: tumour necrosis factor-α; VGDFs: vapours, gases, dusts or fumes.