Summary of studies incorporated in integrated non-linear exposure-response modelling
Reference (year) | Design | Sample size | Exposure source | Mean or median exposure range (SD or IQR) | CKD definition | Adjustments | Exposure contrast | RR (95% CI) | Risk of bias score |
Bowe et al (2018)2 | Cohort | 2 482 737 | PM2.5 | 11.8 (5.0–22.1) | eGFR <60 mL/min/1.73 m2 | Age, race, sex, cancer, cardiovascular disease, chronic lung disease, diabetes mellitus, hyperlipidaemia, hypertension, baseline eGFR, BMI, smoking status, angiotensin-converting enzyme inhibitor/ angiotensin receptor blocker use, county population density, number of outpatient eGFR measurements, number of hospitalisations and county percent in poverty. | Quartile 2 versus 1 | 1.02 (0.97 to 1.07) | 8 |
Quartile 3 versus 1 | 1.07 (1.02 to 1.12) | ||||||||
Quartile 4 versus 1 | 1.14 (1.09 to 1.20) | ||||||||
Chan et al (2018)51 | Cohort | 100 629 | PM2.5 | 27.1 (5.8–49.6) | eGFR <60 mL/min/1.73 m2 | Age, sex, educational level, smoking status, alcohol consumption, BMI, systolic BP, fasting glucose, total cholesterol, self-reported heart disease or stroke and baseline eGFR. | Quintile 2 versus 1 | 1.05 (0.95 to 1.15) | 9 |
Quintile 3 versus 1 | 1.04 (0.94 to 1.15) | ||||||||
Quintile 4 versus 1 | 1.11 (1.01 to 1.22) | ||||||||
Quintile 5 versus 1 | 1.15 (1.05 to 1.26) | ||||||||
Yang et al (2017)52 | Cross-sectional | 21 656 | PM2.5 | 26.6 (5.0) | eGFR <60 mL/min/1.73 m2 | Age, sex, fasting glucose, cholesterol, hypertension, BMI, distance to major road, smoking status, alcohol consumption and education level. | Every 5.67 µg/m3 increase | 1.03 (0.97 to 1.09) | 8 |
Chen et al (2018)50 | Cross-sectional | 8497 | PM2.5 | 24.3 (12.8–48.2) | eGFR <60 mL/min/1.73 m2 | Age, sex, BMI, education level, smoking status, alcohol consumption, hypertension and diabetes. | Every 4.1 µg/m3 increase | 1.01 (0.96 to 1.06) | 9 |
Bragg-Gresham et al (2018)1 | Cross-sectional | 1 164 057 | PM2.5 | 12.2 (6.1–16.8) | eGFR <60 mL/min/1.73 m2 | Age, sex, race/ethnicity, hypertension, diabetes and urban/rural status. | Quartile 2 versus 1 | 1.02 (0.99 to 1.04) | 8 |
Quartile 3 versus 1 | 1.01 (0.98 to 1.03) | ||||||||
Quartile 4 versus 1 | 1.05 (1.03 to 1.07) | ||||||||
Weaver et al (2018)53 | Cross-sectional | 5090 | PM2.5 | 12.2 (0.6) | eGFR <60 mL/min/1.73 m2 | Age, sex, BMI, education level, neighbourhood socioeconomic status, medical insurance, smoking status, physical activity, alcohol consumption, occupation, hyperlipidaemia, use of non-steroidal anti-inflammatory drugs, diuretic medication, statin medications, diabetes and hypertension and accounting for clustering by census tract. | Every 1 µg/m3 increase | 1.00 (0.82 to 1.22) | 9 |
Jhee et al (2018)*54 | Cohort | 1948 | Passive smoking | – | eGFR <60 mL/min/1.73 m2 | Age, sex, BMI, systolic BP, history of hypertension, history of diabetes, alcohol status, education levels, income levels, marital status, haemoglobin and serum albumin. | Moderate secondhand smoke | 1.58 (0.94 to 2.66) | 9 |
Severe secondhand smoke | 1.62 (1.03 to 2.63) | ||||||||
Ejerblad et al (2004)*55 | Case-Control | 1924 | Active smoking | – | eGFR <60 mL/min/1.73 m2 | Age, gender, education level, alcohol consumption, use of paracetamol and salicylates, pipe smoking, cigar smoking and snuff use. | 1–10 cigarettes per day versus no smoking | 0.89 (0.66 to 2.11) | 7 |
11–20 cigarettes per day versus no smoking | 1.24 (0.96 to 1.60) | ||||||||
>20 cigarettes per day versus no smoking | 1.51 (1.06 to 2.15) | ||||||||
Hall et al (2016)*56 | Cohort | 3648 | Active smoking | – | eGFR decline ≥30% | Age, sex, BMI, diabetes, hypertension, total cholesterol, education level, physical activity, prevalent cardiovascular disease and alcohol consumption. | 1–19 cigarettes per day versus no smoking | 1.75 (1.18 to 2.59) | 6 |
>19 cigarettes per day versus no smoking | 1.97 (1.17 to 3.31) | ||||||||
Hippisley-Cox and Coupland (2010)*57 | Cohort | 3 156 494 | Active smoking | – | eGFR <45 mL/min/1.73 m2 | Age, ethnicity, deprivation, smoking, BMI, systolic BP, diabetes, rheumatoid arthritis, cardiovascular disease, treated hypertension, congestive cardiac failure, peripheral vascular disease, use of non-steroidal anti-inflammatory drugs and family history of kidney disease. systemic lupus erythematosus and kidney stones were additional adjusted for models in women. | <10 cigarettes/day versus no smoking in women | 1.30 (1.15 to 1.23) | 7 |
10–19 cigarettes/day versus no smoking in women | 1.27 (1.21 to 1.34) | ||||||||
>19 cigarettes/day versus no smoking in women | 1.43 (1.34 to 1.52) | ||||||||
<10 cigarettes/day versus no smoking in men | 1.15 (1.08 to 1.22) | ||||||||
10–19 cigarettes/day versus no smoking in men | 1.24 (1.16 to 1.32) | ||||||||
>19 cigarettes/day versus no smoking in men | 1.25 (1.16 to 1.34) |
*Incorporated in models when proxy exposures were included.
BMI, body mass index; BP, blood pressure; CKD, chronic kidney disease; eGFR, estimated glomerular filtration rate; PM2.5, ambient fine particulate matter.