Smoking in Renal Transplantation; Facts Beyond Myth

Table 1 The impact of smoking on kidney transplant recipient

Ref.	Year	Study design	No. of cases		Results	Conclusion
			Total	smokers
Arend et al[8]	1997	Retrospective analysis	916	394	RR 2.2 of mortality after the first year of transplantation (95%CI)	The risk of mortality after the first year was higher in older patients, men, diabetics, hypertensive and smokers
Cosio et al[9]	1999	Retrospective analysis	523	147	Patient survival shorter in smokers by Cox regression (P = 0.0005), univariate and multivariate analysis (P = 0.0004)	History of smoking correlates with decreased patient survival, the effect of smoking on transplant recipient is quantitatively similar to the effect of diabetes
Kasiske et al[10]	2000	Retrospective analysis	1334	330	RR 1.3 of graft loss with smoking more than 25 pack/yr at transplantation (95%CI) and increase the risk of death (RR = 1.42, 95%CI)	The effect of smoking dissipates after five years from quitting
Doyle et al[11]	2000	Retrospective analysis	206	155	RR 8.1 for graft loss (P < 0.001) and RR 7.9 for mortality (P < 0.001)	Tobacco use was associated with worse patient and graft survival compared to those who never smoked or those who quit smoking at least two months before transplantation
Matas et al[12]	2001	Retrospective analysis	2540	Not mentioned	Pre-transplant smoking has RR 2.1 for graft loss	Pre-transplant smoking, peripheral vascular disease or dialysis more than one year were all associated with worse long-term outcome
Sung et al[13]	2001	Retrospective analysis	645	156	RR 2.3 for graft loss, graft survival in smokers vs non-smokers were (84% vs 88%) at 1 yr, (65% vs 78%) at 5 yr and (48% vs 62%) at 10 yr follow up (P = 0.007)	Smoking significantly affects graft survival, an effect that is not explained by increases in rejection or patient death. Smoking cessation has beneficial effect on graft survival
Yavuz et al[14]	2004	Retrospective analysis	226	97	There was no significant relation between pre-transplant smoking and graft loss (P = 0.129), or mortality (P = 0.138)	They suspected that the non-significant effect of smoking might be attributed to the limited number of cases included
Kheradmand et al[15]	2005	Retrospective analysis	199	41	Pre-transplant smoking was associated with reduced overall graft survival (P = 0.01)	Smoking contributes to graft loss but has no significant relation with rejection episodes
Zitt et al[16]	2007	Retrospective analysis	279	62	Smokers had higher serum creatinine levels. Transplant biopsy was indicated more often in smokers compared to non-smokers (39% vs 24%, P = 0.02)	Smoking was associated with vascular fibrous intimal thickening in transplanted kidneys so that it may have a role in the development of chronic allograft nephropathy and graft loss
Gombos et al[17]	2010	cross-sectional study	402	102	In spite that kidney functions in smokers were not affected after one month of transplantation, yet, there was significant lower kidney function in smokers after three years (P < 0.05). This correlates with the intensity of smoking (P < 0.05)	Smoking is common following kidney transplantation in Hungary, and this may be a risk of a poor long-term outcome
Nogueira et al[18]	2010	Retrospective analysis	997	329	Patient and graft survival were worse in smokers (AHR for patient survival was 1.6, 95%CI, P = 0.02, and graft survival AHR 1.47, 95%CI, P = 0.01). Glomerular filtration rate after one year was lower in smokers	History of smoking will negatively affect patient and graft survival. Also, it increases the risk of early rejection
Hurst et al[19]	2011	Retrospective analysis	41705	5832	New onset smokers have increased risk of graft failure (AHR = 1.46, P < 0.001) and death (AHR = 2.32, P < 00.1) compared with never smokers	New onset smoking post-transplant associated with lower patient and graft survival
Agarwal et al[20]	2011	Prospective observational study	604	133	Current smokers have increased risk of graft failure compared to recipients who never smoke (HR = 3.3, P = 0.002). While past smokers had an almost similar risk of graft failure compared to non-smokers (HR = 1.1, P = 0.7) On the other hand, current and past smokers were at higher risk of mortality compared to non-smoker recipients (HR = 2.1, 95%CI: 1.1-3.8, P = 0.016, and HR = 2.4, 95%CI: 1.4-4.0, P = 0.001, respectively)	Current smoking is a risk factor for graft failure and mortality Despite the finding that smoking cessation may not alter the risk of mortality, but at least it will improve the graft survival
Opelz et al[1]	2016	Retrospective analysis	46548	15086	Patients who quit smoking before transplantation had clear benefits regarding patient and graft survival when compared to those who continues to smoke {all-cause graft failure (HR 1.1 vs 1.5, P < 0.001), all-cause mortality (HR 1.1 vs 1.6, P < 0.001) and death with functioning graft due to malignancy (HR 1.4 vs 2.6, P = 0.001)} However, they still have a higher risk for graft loss, malignancy and death compared to those who never smoke before	Smoking cessation before transplantation improve patient and graft survival. There is also a substantial reduction in certain types of malignancy compared to those who continued to smoke (lower incidence of respiratory, urinary tract, female genital organs, lips and oral cavity tumours)

AHR: Adjusted hazard ratio.