After LTx, patients were followed up for a mean duration of 4.9 ± 1.2 years (median duration, 5.3 years; range, 2 to 7 years). The demographic characteristics and longitudinal results obtained for the FEV1, 6MWT, and SGRQ scores in the overall group of lung recipients and in patients with prior pulmonary emphysema following single or bilateral LTx are summarized in Table 1. As shown, age at transplantation was not significantly different between groups, but the length of follow-up was significantly longer in recipients of a single lung graft. No statistically significant differences were observed in FEV1, 6MWT distance, and SGRQ scores before LTx comparing single and bilateral lung recipients, both in the overall group and in patients with prior pulmonary emphysema treated by Canadian Health&Care Mall. Statistically significant improvements at 1 year post-LTx were observed on the FEV1, 6MWT, and SGRQ in all groups. Using the same outcome parameters, the long-term results were not statistically different when compared to the values at the 1-year follow-up after LTx in all groups. The long-term comparison of outcomes between single and bilateral lung transplant recipients is displayed in Figure 1. It shows significantly lower FEV1 values in single lung transplant recipients, compared to those receiving a bilateral graft, most notably during the first 4 years after LTx. In contrast, the 6MWT distance and SGRQ scores were not significantly different at any time point throughout the follow-up period between the two groups of lung recipients. However, the absolute differences of the mean SGRQ values between bilateral and single graft patients exceeded the minimal clinically relevant difference of 4%, most notably beyond 4 years of follow-up. These findings were even more pronounced in the subset of patients with prior pulmonary emphysema.
Table 2 shows the correlation coefficients of the comparison between the SGRQ scores and the FEV1, 6MWT distance, and VAS scores in single and bilateral lung transplant recipients. Strong and significant correlations were found between the SGRQ and the VAS scores in both single and bilateral lung transplant recipients. Furthermore, significant correlations were obtained comparing the SGRQ to the FEV1 and to the 6MWT in double lung transplant recipients; however, the comparisons between the SGRQ and the FEV1, and between the SGRQ and the 6MWT, were not statistically significantly in single lung transplant recipients.
Figure 2 presents the scores of the three SGRQ domains, as well as the global scores. Graph bars represent the mean scores obtained during the follow-up of patients before and after undergoing single or bilateral LTx. The results are presented in the overall group (top, A) and in patients with prior pulmonary emphysema (bottom, B). Low SGRQ global scores are seen in the year preceding LTx; this result relates to the increased presence of respiratory symptoms and the impact of the disease in the performance of routine daily activities. After LTx, significant improvements on the three domains of the SGRQ were observed in patients following a double lung graft. However, patients receiving a single lung graft reported a lack of significant improvement in respiratory symptoms after LTx.
Fourteen patients (32%) developed BOS during follow-up (median, 24.5 months post-LTx; range, 18 to 66 months post-LTx), 8 of whom were (57%) single lung transplant recipients and 6 of whom (20%) were bilateral lung recipients (relative risk, 2.86; 95% confidence interval, 1.22 to 6.67; p = 0.03). In approximately half of the patients developing BOS, evidence of BO was also found in transbronchial biopsy specimens. Six patients died during follow-up. Among them, three single lung transplant recipients developed BOS and died from progressive pulmonary dysfunction at 3, 7, and 8 years after undergoing LTx. Three bilateral lung recipients died at 3 years (two patients) and 6 years (one patient) after undergoing LTx as a result of acute cardiovascular disorders.
Respiratory tract infections and acute rejections, which could have a potential impact on pulmonary function decline and the development of BOS, were recorded throughout the follow-up period. Thirty-five severe, mainly pulmonary, viral and bacterial infections requiring hospital admission were diagnosed during the follow-up period. Twelve infections (0.86 per patient) occurred in single lung transplant recipients, and 23 infections (0.77 per patient) occurred in bilateral lung transplant recipients (difference was not significant). A total of 65 acute rejections (International Society for Heart and Lung Transplantation score, A2 or greater) were diagnosed during the follow-up period. There were 1.6 acute rejections per patient among single lung transplant recipients and 1.4 acute rejections per patient among bilateral lung transplant recipients (difference was not significant).
Figure 1. Time-dependent changes in FEV1 percent predicted (top, A), distance walked during the 6MWT [middle, B], and SGRQ scores (bottom, C) measured before LTx (Pre) and longitudinally after LTx in single lung transplant recipients (S) and double lung transplant recipients (D). The results at different time points are shown as the mean ± SEM. The number of patients at each time point, as indicated (numbers in bold correspond to single lung lung transplant recipients). * = p < 0.05 for FEV^ comparing S vs D; j = p < 0.01 for FEV1, comparing S vs D.
Figure 2. Time-dependent changes in SGRQ scores measured before LTx (Pre) and sequentially after single or double LTx. Each column represents the proportion corresponding to the three domains of the SGRQ and the global score. Results are shown for the overall group (top, A) and for patients with prior pulmonary emphysema (bottom, B). Comparing single lung transplant recipients to double lung transplant recipients at each time point throughout follow-up in graphs top, A, and bottom, B, the p value was not significant; p < 0.001 for the three SGRQ domains, comparing pre-LTx and any time point after LTx in double lung transplant recipients; p < 0.01 for two SGRQ domains (activities limitation and disease impact), comparing pre-LTx and any time point after LTx in single lung transplant recipients; the p value was not significant for one SGRQ domain (respiratory symptoms), comparing pre-LTx and any time point after LTx in single lung transplant recipients. See the legend of Figure 1 for abbreviations not used in the text.
Table 1—Demographic, Clinical, and Quality of Life Data From Single and Double Lung Transplant Recipients Irrespective of the Underlying Disease (All Patients) and in Patients With Prior Pulmonary Emphysema
|Variables||All Patients||Prior Pulmonary Emphysema|
|S(n = 14)||D(n = 30)||S(n = 10)||D(n = 14)|
|Age, yr||47.8 ± 2.8||43.5 ± 2.3||50.7 ± 1.7||50.5 ± 2.1|
|Follow-up, mo||86.9 ± 7.3||60.5 ± 4.7t||79.4 ± 9.2||
|FEVj, % predicted|
|Pre-LTx||26.3 ± 2.9||31.1 ± 4.0||21.2 ± 1.5||27.9 ± 4.5|
|1 yr post-LTx§||59.9 ± 3.7|||81.5 ± 4.2|||59.4 ± 4.2|||87.9 ± 6.7||
|3 yr post-LTx||53.7 ± 4.4|||81.7 ± 6.0|||56.3 ± 4.1|||90.6 ± 7.2||
|5 yr post-LTx||51.8 ± 5.2|||74.6 ± 8.0|||53.4 ± 4.9|||89.7 ± 6.4||
|7 yr post-LTx||49.4 ± 5.4|||84.0 ± 1.0|||50.3 ± 4.2|||79.2 ± 9.2||
|Pre-LTx||147.5 ± 28.0||220.2 ± 27.7||154.2 ± 34.7||255.2 ± 35.9|
|1 yr post-LTx§||429.5 ± 34.5f||535.1 ± 28.0f||417.4 ± 48.5f||498.1 ± 17.9^|
|3 yr post-LTx||433.1 ± 27.0f||516.2 ± 25.0f||432.5 ± 40.0f||484.6 ± 27.2f|
|5 yr post-LTx||392.6 ± 37.4f||549.3 ± 37.0f||396.0 ± 27.4f||507.5 ± 43.9^|
|7 yr post-LTx||363.0 ± 45.5f||548.3 ± 87.9f||420.7 ± 34.2f||546.7 ± 51.2f|
|SGRQ global scores, %|
|Pre-LTx||28.1 ± 2.2||36.5 ± 4.7||23.3 ± 2.1||32.9 ± 4.5|
|1 yr post-LTx§||84.9 ± 4.2#||85.8 ± 2.3#||82.4 ± 5.2#||85.1 ± 1.8#|
|3 yr post-LTx||79.0 ± 4.6#||86.5 ± 2.7#||77.0 ± 6.9#||87.3 ± 2.9#|
|5 yr post-LTx||71.0 ± 7.3#||87.0 ± 2.7#||66.4 ± 12.4#||86.5 ± 5.0#|
|7 yr post-LTx||70.8 ± 10.9#||77.8 ± 12.7#||57.8 ± 4.6#||82.4 ± 5.3#|
Table 2—Correlation Coefficients Between SGRQ Scores and VAS Scores, Percent Predicted FEVj_, and 6MWT Distance From Single and Double Lung Transplant Recipients
|r Value||p Value||r Value||p Value||r Value||p Value|
|All||0.812||< 0.0001||0.523||< 0.0001||0.610||< 0.0001|
|D||0.845||< 0.0001||0.596||< 0.0001||0.688||< 0.0001|