Table 1

Summary of studies incorporated in integrated non-linear exposure-response modelling

Reference (year)DesignSample sizeExposure sourceMean or median exposure range (SD or IQR)CKD definitionAdjustmentsExposure contrastRR (95% CI)Risk of bias score
Bowe et al (2018)2Cohort2 482 737PM2.511.8 (5.0–22.1)eGFR <60 mL/min/1.73 m2Age, 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 11.02 (0.97 to 1.07)8
Quartile 3 versus 11.07 (1.02 to 1.12)
Quartile 4 versus 11.14 (1.09 to 1.20)
Chan et al (2018)51Cohort100 629PM2.527.1 (5.8–49.6)eGFR <60 mL/min/1.73 m2Age, 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 11.05 (0.95 to 1.15)9
Quintile 3 versus 11.04 (0.94 to 1.15)
Quintile 4 versus 11.11 (1.01 to 1.22)
Quintile 5 versus 11.15 (1.05 to 1.26)
Yang et al (2017)52Cross-sectional21 656PM2.526.6 (5.0)eGFR <60 mL/min/1.73 m2Age, sex, fasting glucose, cholesterol, hypertension,
BMI, distance to major road, smoking status, alcohol consumption and education level.
Every 5.67 µg/m3 increase1.03 (0.97 to 1.09)8
Chen et al (2018)50Cross-sectional8497PM2.524.3 (12.8–48.2)eGFR <60 mL/min/1.73 m2Age, sex, BMI, education level, smoking status, alcohol consumption, hypertension and diabetes.Every 4.1 µg/m3 increase1.01 (0.96 to 1.06)9
Bragg-Gresham et al (2018)1Cross-sectional1 164 057PM2.512.2 (6.1–16.8)eGFR <60 mL/min/1.73 m2Age, sex, race/ethnicity, hypertension, diabetes and urban/rural status.Quartile 2 versus 11.02 (0.99 to 1.04)8
Quartile 3 versus 11.01 (0.98 to 1.03)
Quartile 4 versus 11.05 (1.03 to 1.07)
Weaver et al (2018)53Cross-sectional5090PM2.512.2 (0.6)eGFR <60 mL/min/1.73 m2Age, 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 increase1.00 (0.82 to 1.22)9
Jhee et al (2018)*54Cohort1948Passive smokingeGFR <60 mL/min/1.73 m2Age, sex, BMI, systolic BP, history of hypertension, history of diabetes, alcohol status, education levels, income levels, marital status, haemoglobin and serum albumin.Moderate secondhand smoke1.58 (0.94 to 2.66)9
Severe secondhand smoke1.62 (1.03 to 2.63)
Ejerblad et al (2004)*55Case-Control1924Active smokingeGFR <60 mL/min/1.73 m2Age, gender, education level, alcohol consumption, use of paracetamol and salicylates, pipe smoking, cigar smoking and snuff use.1–10 cigarettes per day versus no smoking0.89 (0.66 to 2.11)7
11–20 cigarettes per day versus no smoking1.24 (0.96 to 1.60)
>20 cigarettes per day versus no smoking1.51 (1.06 to 2.15)
Hall et al (2016)*56Cohort3648Active smokingeGFR 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 smoking1.75 (1.18 to 2.59)6
>19 cigarettes per day versus no smoking1.97 (1.17 to 3.31)
Hippisley-Cox and Coupland (2010)*57Cohort3 156 494Active smokingeGFR <45 mL/min/1.73 m2Age, 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 women1.30 (1.15 to 1.23)7
10–19 cigarettes/day versus no smoking in women1.27 (1.21 to 1.34)
>19 cigarettes/day versus no smoking in women1.43 (1.34 to 1.52)
<10 cigarettes/day versus no smoking in men1.15 (1.08 to 1.22)
10–19 cigarettes/day versus no smoking in men1.24 (1.16 to 1.32)
>19 cigarettes/day versus no smoking in men1.25 (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.