Abstract and Introduction
Abstract
Chronic kidney disease (CKD) is a common complication after lung transplantation (LTx). Smoking is a risk factor for many diseases, including CKD. Smoking cessation for >6 months is required for LTx enlistment. However, the impact of smoking history on CKD development after LTx remains unclear. We investigated the effect of former smoking on CKD and mortality after LTx. CKD was based on glomerular filtration rate (GFR) (I-iothalamate measurements). GFR was measured before and repeatedly after LTx. One hundred thirty-four patients never smoked and 192 patients previously smoked for a median of 17.5 pack years. At 5 years after LTx, overall cumulative incidences of CKD-III, CKD-IV and death were 68.5%, 16.3% and 34.6%, respectively. Compared to never smokers, former smokers had a higher risk for CKD-III (hazard ratio [HR] 95% confidence interval [95%CI]= 1.69 [1.27–2.24]) and IV (HR = 1.90 [1.11–3.27]), but not for mortality (HR = 0.99 [0.71–1.38]). Adjustment for potential confounders did not change results. Thus, despite cessation, smoking history remained a risk factor for CKD in LTx recipients. Considering the increasing acceptance for LTx of older recipients with lower baseline renal function and an extensive smoking history, our data suggest that the problem of post-LTx CKD may increase in the future.
Introduction
Chronic kidney disease (CKD) is a serious complication after lung transplantation (LTx). In most LTx recipients renal function deteriorates progressively, often resulting in CKD. Progression from CKD to end-stage renal disease (ESRD) currently develops in between 3% and 10% of LTx recipients. Recipient age and life expectancy after LTx are increasing, so it is likely that the a priori risk for CKD after LTx is increasing concomitantly, with possible consequences for the number of LTx recipients that develop ESRD on the long term.
Approximately 60% of LTx recipients have a history of smoking. This is the highest rate reported among recipients of solid organs: former smokers account for 51–54% of renal-transplant recipients, 42–50% of liver-transplant recipients and 45% of heart-transplant recipients. Moreover, many former smokers among LTx recipients smoked heavily, as around 40–45% of them undergo LTx because of end-stage pulmonary emphysema, which is largely attributable to heavy smoking. Pulmonary emphysema, cardiovascular disease and lung cancer are well-known complications of smoking. It may be less well known that smoking is also a risk factor for CKD. We wondered whether, even after smoking cessation, smoking history could be relevant for morbidity after LTx, in particular CKD, because of the high prevalence of both CKD and former smoking in LTx recipients.
Transplant centers, including our own, commonly require that patients have stopped smoking for at least 6 months before being enlisted for LTx. In this study, we analyzed the potential association between smoking history before LTx and development of CKD after LTx in a large single center cohort of LTx recipients. In addition, we analyzed the impact of past smoking on mortality and causes of death after LTx.