Report: DUAN LianNing, LUO Yuan, LU ChengRong, XU XianRong, WANG JianChang

Analysis of Medical Evaluation of Hematological Diseases in 83 Air Force Aircrews

The aim of this paper is to analyze the characteristics of hematological diseases in 83 Air Force aircrews and investigate its relationship to their flying ability and medical evaluation. Our results suggest that most aircrew patients can return to flying position after treatment except malignant or progressive diseases. The medical evaluation should be made according to the nature and prognosis of disease，therapeutic efficacy, as well as the flying airplane type.

Introduction

Health assessment of aircrews is very important to maintain flight safety and guarantee continuous operation. Environmental and physical factors in flight could influence blood immune regulation. Till now, the identification basis of blood-immune system diseases is still in shortage because of low incidence, diverse symptom and different treatment effect. Here, we review 83 cases of aircrew suffering from hematological diseases hospitalized in General Hospital of Chinese Air Force, hoping to provide valuable references for flight identification.

Subjects and methods

83 cases of aircrew (average age 32.6±6.3 years) suffering from hematological diseases were hospitalized in General Hospital of Air Force were reviewed. The flying airplanes included fighter, transporter and helicopter. The suffered diseases included anemia, myeloproliferative disease, malignant lymphoma, acute leukemia, and so on.

All patients were diagnosed and verified by hematological physician, meeting the WHO diagnostic criteria for blood diseases. According to Air Force flight crew medical examination standards, hospital identification committee made the final qualification of flight. Then, we discuss the possible relation between disease and health conclusion. All data were processed by SPSS 17.0 software.

Results

1. Disease distribution and flight conditions

Leucopenia, Thrombocytopenia, Anemia and Marrow proliferating disease are the major types of diseases. The mean age of malignant lymphoma group is 38.67 year, which is the oldest in all. The mean flight time of leukemia group is 2886 hours, which is the longest in all

2. Comparison between benign and malignant diseases

Malignant diseases include leukemia, malignant lymphoma and histiocytosis. While, benign diseases contain leucopenia, thrombocytopenia, anemia, and so on. There’re no significant differences of pilot’s age between benign and malignant diseases group (P>0.05), and the same to total flight time.

3. Conclusions of flight conditions

After treatment, 47 pilots (56.6%) in 83 were flight qualified, including 23 pilots suffering from leucopenia, 10 pilots suffering from thrombocytopenia, 5 pilots suffering from anemia, 5 pilots suffering from marrow proliferating disease, 3 pilots suffering from malignant lymphoma. Grounding is mainly due to malignant diseases, especially acute leukemia. All 5 pilots with leukemia were fight unqualified.

Discussion

Diagnosis and treatment of blood diseases has developed rapidly in recent years and it forms a great challenge to flight qualification. Take chronic myeloid leukemia for example, current treatment is using Gleevec alone, which could make 90% patients achieve complete remission and obtain long-term survival, instead of using traditional bone marrow transplantation. Also, patients suffering from Diffuse large B cell lymphoma (DLBCL) could get a high quality long-term survival from Rituximab treatment. However, flight appraisal is still lack basis on such malignant diseases which could benefit a lot from the advantage of medical science and technology.

The incidence of pilots suffering from leucopenia has increased gradually. Our data shows that about 85% patients could return to flight after treatment. Once their leukocytes regain to 3.7 G/L and there are no other symptoms, they could return to flight and even update a high-performance aircraft. However, flight qualification of pilots with thrombocytopenia is much more complicated. If accompanied with the decrease of megakaryocytes’ quality and quantity, especially when platelet levels fluctuates in 50-80×109/L after medication, it should be negative. If they’re non-pilot aircrews, it could be positive when platelet levels stabilize above 50×109/L and there’re no adverse symptoms. The main reasons for Iron deficiency anemia are upper gastrointestinal bleeding and uterine fibroids. It could be flight qualified after cure. On the contrary, it should be grounded when suffering from aplastic anemia.

Marrow proliferating disease is chronic and progressive. It could be flight qualified without any increase of lymphocytes or platelets, particular symptoms and gene aberrations. Once concurrent with myelofibrosis or bone marrow dysplasia, it should be grounded. Since 5-20% marrow proliferating disease could evolve into leukemia, it’s very important to monitor regularly. For young flight crews with long flight time, aviation doctors should be vigilant in periodic medical examinations. It should be highly suspected lymphoma when finding chronic, painless and progressive lymphadenopathy, especially those accompanied with long-term fever and progressive weight loss. Currently, PET-CT examination and LDH monitor is very important to the diagnosis and prognosis of malignant lymphoma. Data from ordinary patients receiving anti-CD20 antibody therapy suggest that pilots with malignant lymphoma, who achieve remission after chemotherapy and receive anti-CD20 antibody therapy, could be flight qualified. In addition, our data shows that all five cases of leukemia pilots were flight unqualified. Two of them survived for more than 10 years and have changed to do ground work..

In short, the medical evaluation should be made according to the nature and prognosis of diseases, therapeutic efficacy, as well as the flying airplane type. The majority of pilots with benign diseases could be flight qualified after treatment. However, those with malignant diseases need individual assessment, only a part of them could continue their flying career.