Allogeneic hematopoietic stem cell transplantation in the active duty military population: 1987-2001

Military Medicine, Jan 2003 by Ornstein, Deborah L

Wilford Hall Medical Center at Lackland Air Force Base is the only military medical center in the United States at which allogeneic hematopoietic stem cell transplants (HSCT) are performed. Through May 2001, 367 patients, including 163 active duty service members, have received allogeneic HSCT from related donors. We performed a retrospective review of the outcomes of allogeneic HSCT in active duty members to determine what proportion was returned to full-time military service after HSCT and to delineate the factors associated with successful return to military service. Twenty-one percent of service members who received allogeneic HSCT were returned to active duty at some point after treatment. Age, sex, branch of service, and rank had no significant influence on return to duty status. When adjusted for age and rank, the only significant predictor of successful return to active duty was a diagnosis of chronic myelogenous leukemia. Although individuals with good risk diseases such as aplastic anemia, myelodysplastic syndrome, paroxymal nocturnal hemoglobinuria, and acute myelogenous leukemia in first complete remission have also been returned active duty after HSCT, these diagnoses were not statistically predictive of a return to active duty. We conclude that it may be possible to predict which service members will return to active duty after allogeneic HSCT based on the disease for which HSCT is being performed. Most importantly, active duty service members need not be a priori medically retired after HSCT, and each return to duty decision must be individualized.

Introduction

As the only U.S. military medical center at which allogeneic hematopoietic stem cell transplants (HSCT are performed, the Fisher Bone Marrow Transplant Unit at Wilford Hall Medical Center (WHMC) has a unique role in military medicine. The Fisher Bone Marrow Transplant Center was established in 1987 at WHMC as a 5-year Department of Defense demonstration project to evaluate the feasibility of performing matched related donor allogeneic HSCT within the military medical system. Through May 2001, nearly 1,000 HSCT have been performed in military health care beneficiaries, including 367 allogeneic procedures. Patients have undergone allogeneic HSCT for numerous malignant and benign hematologic disorders, including acute and chronic myelogenous leukemia (AML, CML), acute and chronic lymphocytic leukemia, multiple myeloma, myelodysplastic syndromes (MDS), agnogenic myeloid metaplasia with myelofibrosis, Hodgkin's and non-Hodgkin's lymphomas, aplastic anemia, and paroxysmal nocturnal hemoglobinuria (PNH). Of the 367 allogeneic HSCT recipients treated at WHMC since the inception of the transplant program, 163 of these were active duty members from all branches of the Armed Services.

Allogeneic HSCT is a curative treatment for many hematologic disorders, and the ultimate goal of treatment is to restore patients to their previous level of functioning. We have, therefore, undertaken a retrospective analysis of clinical outcomes in active duty members undergoing allogeneic HSCT to determine what proportion was returned to active duty military service after recovery from HSCT. A secondary aim of this study was to determine what, if any, factors (e.g., age, sex, type of hematologic disorder, branch of service, military rank) predicted a successful return to active duty service after allogeneic HSCT. Our goal is to use these data to identify prospective patients who are likely to resume military careers after HSCT and, likewise, patients who are unlikely to return to active duty and who may therefore benefit from immediate medical retirement soon after the diagnosis of a hematologic disorder is made.

Historically, the term, "bone marrow transplantation" has been used to describe the process of transplanting hematopoietic stem cells from a donor to a recipient. However, alternative sources of stem cells, including peripheral and umbilical cord blood, are increasingly being used in place of bone marrow. Accordingly, we have adopted the more appropriate term to describe this process, "hematopoietic stem cell transplantation," throughout this text.

Methods

The records of all active duty members referred for allogeneic HSCT from January 1987 through May 2001 were reviewed. Data were compiled on age, sex, military status (service branch and rank), and disease status at the time of HSCT. The current military status of surviving patients was verified whenever possible by telephone contact with the patient him/herself or, alternatively, with a family member. Pearson's chi^sup 2^, chi^sup 2^ likelihood ratios, or Student's t tests were used to evaluate the significance of differences detected between the group of HSCT patients returned to active duty and the group of patients not returned to duty. Logistic regression analysis was used to determine which variables were associated with a return to active duty military service.

Results

Patient Characteristics

The characteristics of the 163 patients who underwent allogeneic HSCT during the period under study are summarized in Table I. The majority of active duty patients undergoing HSCT at WHMC were men with a median age of 33 years. Moreover, most of the WHMC HSCT patients have been from the enlisted ranks, reflecting the composition of the larger military population. The most common disease for which HSCT was performed in active duty personnel was CML, followed by AML. Most patients undergoing HSCT to date have been from the Army, followed by the Navy, Air Force, Marine Corps, and Coast Guard, once again reflecting the composition of the military force as a whole.