Table 1. Characteristics of included studies.

Author, Year (country)	Sample characteristics	Follow-up period	Criteria for smoking status	Criteria	Criteria of unstable	Adjustment
Zitt et al.,2016 (Austria)	185,341 individuals (99,881 women and 85,460 men) aged 30–70 years	17.5±6.1 years	Current smokers	Registry ESRD	Registry ESRD	Sex, age, Sample size, Follow-up period, criteria
Feodoroff et al.,2016 (Italy)	3613 individuals (1844 men) aged 27–45 years	15 years	Former smokers Current smokers	UAER: 30mg/24h	UAER	Sex, age, Sample size, Follow-up period, criteria
Zoppini et al.,2009 (USA)	1987 individuals(1197men and 790 women) aged 55–79years	5 years	Current smokers	GFR 60 mL/min/1.73 m2	GFR	Sex, age, Sample size, Follow-up period, criteria
Cederholm et al., 2005 (Sweden)	6513 individuals aged 50–75 years	4.6 years	T1DM Current smokers T2DM Current smokers	Microalbuminuria: >20ug/min	Microalbuminuria	Sex, Sample size, age, Follow-up period, criteria
Rossing et al.,2002 (Denmark)	537 individuals (278 men) aged 25–60 years	10 years	Current smokers	Proteinuria>30mg/d	Proteinuria	Sex, Sample size, age, Follow-up period, criteria
Scott et al.,2001 (USA)	943 individuals aged 15–44 years	4 years	Former smokers Current smokers	Microalbuminuria	Microalbuminuria	Sex, age, Sample size, Follow-up period, criteria
RCPE Diabetes Register Group.,2000 (UK)	1201 individuals (565 women and 636 men) aged 25–55 years	4 years	Former smokers Current smokers	consecutive UAR > 200 mg/l or a single > 1000 mg/l	consecutive UAR or a single	Age, Sex, Sample size, Follow-up period, criteria
Yokoyama et al.,1998 (Japan)	426 individuals aged 50–60 years	4.7 years	Current smokers	persistent proteinuria: >300mg/l	persistent proteinuria	Age, Sex, Sample size, Follow-up period, criteria
Klein et al.,1995 (UK)	2776individuals aged (996Younger-onset; 1780 Older-onset )	10 years	Pack-year≤9 Pack-year>9	Proteinuria>0.3 g/l	Proteinuria	Age, Sex, Sample size, Follow-up period, criteria