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Communications to the Editor |

Analysis of Results in Posttransplant Lymphoproliferative Disorder Analysis of Results in Posttransplant Lymphoproliferative Disorder FREE TO VIEW

Lianne G. Singer; James Theodore, MD, FCCP; Michael K. Gould, MD, MSc
Author and Funding Information

Affiliations: Heart-Lung and Lung Transplant Program Stanford University Stanford, CA VA Palo Alto Health Care System Palo Alto, CA,  The University of Texas Health Science Center at San Antonio San Antonio, TX

Correspondence to: Lianne G. Singer, MD, Heart-Lung and Lung Transplant Program, Stanford University Medical Center, 300 Pasteur Dr, Room H3143, Stanford, CA 94305-5236; e-mail: lsinger@stanford.edu



Chest. 2000;118(4):1227-1228. doi:10.1378/chest.118.4.1227
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Published online

To the Editor:

We read with interest the article by Levine et al (November 1999)1describing the experience of one lung transplant center with posttransplant lymphoproliferative disorder (PTLD). The authors are fortunate to have diagnosed PTLD in only 1.8% of their transplant recipients to date. They state that their observed cumulative incidence of PTLD of 20% in Epstein-Barr virus (EBV) seroconverters was lower than the incidence of 42% reported in a similar previous study by Aris et al.2 They speculate that the low observed incidence of PTLD may be due to a more dose-intensive protocol of acyclovir prophylaxis.

We calculated 95% confidence intervals for the observed incidence of PTLD in EBV seroconverters for each of these two studies. We also compared risk ratios for the association between PTLD and pretransplant EBV seronegativity in the two studies (Table 1 ). We included subjects with pretransplant and posttransplant EBV serology available who survived for > 1 month. Cumulative incidence proportions were compared using Fisher’s Exact Test, while risk ratios were compared using the Mantel-Haenszel test for homogeneity (Stata version 6.0; Stata Corporation; College Station, TX).

Because of the wide confidence intervals for PTLD incidence in EBV seroconverters, one cannot conclude that the prevalence estimates are different across the two studies. In fact, the upper limits of the 95% confidence intervals are identical. More strikingly, the relative risks of PTLD by EBV serostatus are nearly identical when the two studies are compared. These results suggest that the low observed incidence of PTLD in the authors’ center is due entirely to the low prevalence of EBV seronegativity in their recipient population and cannot be attributed to any difference in patient management.

Table Graphic Jump Location
Table 1. Comparison of PTLD Studies in Lung Transplant Recipients
* 

p = 0.6.

 

p = 0.7.

Levine, SM, Angel, L, Anzueto, A, et al (1999) A low incidence of posttransplant lymphoproliferative disorder in 109 lung transplant recipients.Chest116,1273-1277. [CrossRef] [PubMed]
 
Aris, RM, Maia, DM, Neuringer, IP, et al Post-transplantation lymphoproliferative disorder in the Epstein-Barr virus-naive lung transplant recipient.Am J Respir Crit Care Med1996;154,1712-1717. [PubMed]
 

Analysis of Results in Posttransplant Lymphoproliferative Disorder

To the Editor:

The further statistical analysis of the posttransplant lymphoproliferative disorder (PTLD) data from our center is appreciated. We agree with the comments made by Dr. Singer and colleagues. Indeed, the low incidence of PTLD at our center may be due to the low prevalence of Epstein-Barr virus (EBV) seronegativity in our transplant group.

As for our comparison between the PTLD incidences in EBV seroconverters in the study by Aris et al1and our study (November 1999),2 I am sure that Dr. Singer and colleagues are aware that due to the small sample sizes in both studies, the power to detect differences between incidences is extremely low. In fact, a Fisher’s Exact Test with α = 0.05 (two sided) will have only 7% power to detect the difference between a proportion of 20% and 42% when the sample sizes are 5 and 12, respectively. Therefore, our statement contrasting the two studies was intended to be purely observational.

We would also like to comment that we have remained “fortunate” with our low overall incidence of PTLD. Recent analysis of our lung transplant patients (who have survived > 1 month following transplantation) reveals a total of six EBV-seronegative converters with, to date, only the single case of PTLD as previously reported in this group (1 of 6; 16.7%). We also have an additional 19 seropositive transplant recipients without additional cases of PTLD other than the one previously reported (1 of 123; 0.8%). Thus, our overall PTLD incidence is 2 of 129 (1.6%), with a follow-up of > 4,800 patient-months. For now, at our center, we will continue using the currently successful, prolonged antiviral prophylactic regimen described in the article.

References
Aris, RM, Maia, DM, Neuringer, IP, et al Post-transplantation lymphoproliferative disorder in the Epstein-Barr virus-naïve lung transplant recipient.Am J Respir Crit Care Med1996;154,1712-1717. [PubMed]
 
Levine, SM, Angel, L, Anzueto, A, et al A low incidence of posttransplant lymphoproliferative disorder in 109 lung transplant recipients.Chest1999;116,1273-1277. [CrossRef] [PubMed]
 

Figures

Tables

Table Graphic Jump Location
Table 1. Comparison of PTLD Studies in Lung Transplant Recipients
* 

p = 0.6.

 

p = 0.7.

References

Levine, SM, Angel, L, Anzueto, A, et al (1999) A low incidence of posttransplant lymphoproliferative disorder in 109 lung transplant recipients.Chest116,1273-1277. [CrossRef] [PubMed]
 
Aris, RM, Maia, DM, Neuringer, IP, et al Post-transplantation lymphoproliferative disorder in the Epstein-Barr virus-naive lung transplant recipient.Am J Respir Crit Care Med1996;154,1712-1717. [PubMed]
 
Aris, RM, Maia, DM, Neuringer, IP, et al Post-transplantation lymphoproliferative disorder in the Epstein-Barr virus-naïve lung transplant recipient.Am J Respir Crit Care Med1996;154,1712-1717. [PubMed]
 
Levine, SM, Angel, L, Anzueto, A, et al A low incidence of posttransplant lymphoproliferative disorder in 109 lung transplant recipients.Chest1999;116,1273-1277. [CrossRef] [PubMed]
 
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