Cigarette smoking and chronic allograft nephropathy.

BACKGROUND Smoking has been demonstrated to decrease patient and graft survival after kidney transplantation. Data on histological changes associated with smoking in renal allografts are lacking. METHODS Smoking habits before and after renal transplantation were evaluated by questionnaire in 279 patients. A transplant biopsy was performed more than 1 year after transplantation in 76 of them. Histological changes were classified according to Banff 97 criteria. Linear regression analysis and proportional odds models for histological changes including the factors age, gender, diabetes, body mass index, donor age, time since transplantation, history of acute rejection and smoking status were calculated. RESULTS Overall 22% of patients continued smoking after transplantation, with the proportion decreasing from 38% of those transplanted before 1990 to 13% of those transplanted after 2000. Serum creatinine was non-significantly higher in smokers (2.3 +/- 2.7 mg/dl vs 1.8 +/- 1.4 mg/dl, P = 0.21). A renal biopsy was performed in 24% of non-smokers and 39% of smokers (P = 0.02), and smokers were biopsied on average 1.5 years earlier. Among biopsied patients current smokers tended to suffer more often from diabetes (25.0% vs 13.5%, P = 0.33), to develop transplant failure (33.3% vs 21.2%, P = 0.25) or experience a cardiovascular event (29.2% vs 15.4%, P = 0.16). The frequency of acute rejection was comparable between smokers and non-smokers (25.0% vs 34.6%, P = 0.40). Glomerular sclerosis was associated with diabetes (P = 0.03). Severity of vascular intimal fibrous thickening was associated with current smoking (P = 0.004), whereas the degree of arteriolar hyalinosis (P < 0.001) and chronic/sclerosing nephropathy (P = 0.05) were associated with time since transplantation. CONCLUSIONS The number of patients who continue cigarette smoking after renal transplantation has decreased in recent years. The main allograft lesion associated with smoking is fibrous intimal thickening of small arteries.