Epidemiology and Clinical Outcomes in Children with Aplastic Anemia in Korea: Retrospective Study

Jeong, Dae Chul; Kang, Im Joo; Koo, Hong Hoe; Kook, Hoon; Kim, Sun Young; Kim, Soon Ki; Kim, Hwang Min; Kim, Heung Sik; Park, Kyung Duk; Park, Kyeong Bae; Park, Young Sil; Park, Sang Kyu; Park, Jae Sun; Park, Jun Eun; Park, Hyeon Jin; Seo, Jong Jin; Suh, Won Suk; Sung, Ki Woong; Shin, Hee Young; Ahn, Hyo Seop; Yang, Chang Hyun; Yoo, Keon Hee; Ryu, Kyung Ha; Yoo, Eun Sun; Lyu, Chuhl Joo; Lee, Kun Soo; Lee, Kwang Chul; Lee, Soon Yong; Lim, Young Tak; Jang, Pil Sang; Chung, Nak Gyun; Jung, Hye Lim; Cho, Bin; Choi, Yong Mook; Hah, Jeong Ok; Hwang, Tai Ju

Abstract

PURPOSE
The annual incidence of aplastic anemia (AA) in Asian countries is higher than in Western countries. The pathogenesis in AA has been investigated in hematopoiesis and immunology. Recently, the survival rate and the quality of life of the patients with AA have been steadily improved by the development of a variety of treatments such as the immunosuppressive therapy (IST), and hematopoietic stem cell transplantation (HSCT). The Korean Society of Pediatric Hematology-oncology retrospectively investigated the incidence, treatment strategies, survival rate, and time to become independent from transfusion in patients with AA, who were diagnosed from January 1st, 1991 to December 31st, 2000 in Korea. METHODS: All the questionnaires were sent to a group of training hospitals, and we collected about 600 questionnaire forms from 27 hospitals. However, 493 reports were available for data analysis. RESULTS: The male and female ratio in AA is 1.1 (259 males vs. 234 female). The median age at diagnosis is 9 years old (range; 0.8~16 years old). The annual incidence of children with AA in Korea is 4.5 per million on the basis of Korean pediatric population. In etiology, there are 20 cases (4.1%) in congenital and others in acquired AA. In acquired AA, the cause of illness was not identifiable for most of the patients, but 1 patient had hepatitis-associated AA, and 3 patients developed the illness after medication. According to the initial laboratory data at diagnosis, the peripheral blood findings showed that hemoglobin is 7.1+/-2.4 g/dL, white blood cell 3, 200/microL (200~16, 550), absolute neutrophil counts 670/microL (0~12, 487), platelets 19, 000/microL (1, 000~500, 000), and corrected reticulocytes 0.18% (0.0~4.7). The bone marrow examination revealed that cellularity was below 25% in 348 patients, and over 25% in 105 patients. In the available data, 269 patients (54.6%) were diagnosed of severe aplastic anemia (SAA) and 224 patients of non-SAA (NSAA). HSCT were done for 96 patients (19.5%) and others received another treatments such as the IST. The anti-thymocyte globulin (ATG) or anti-lymphocyte globulin (ALG) treatment was done for 263 cases, corticosteroids for 259, cyclosporine A (CSA) for 215, and anabolic steroids for 138. The combination IST including ATG or ALG plus corticosteroid plus CSA were applied to 154 children with AA, and transfusion only in 37, as conservative care. In case of those patients with HSCT, the time from diagnosis to transplantation was 12 months (1~144 months) and the sources of stem cells were bone marrow in 82 cases, growth factor mobilized peripheral blood in five, and cord blood in six. There were 57 patients transfused below 40 units of blood products before HSC transplantation. Graft rejection was identified from 16 patients, and booster transplantations were done for 12 patients among them. In complications of HSCT, the graft versus host disease was developed in 20 patients and viral diseases in 12 cases including the CMV, herpetic infection, and hepatitis. Also, one patient suffered from veno-occlusive disease. The overall survival rate in children with AA is 64.3%. The survival rate in HSCT is better than that IST (76.9% vs. 62.6%, P< 0.05). In IST, overall survival rate in very SAA showed lower than SAA and NSAA, and in SAA lower than NSAA in case of absolute neutrophil count below 200/microL (P< 0.05). There was no significant difference in terms of the sex, age at beginning of treatment. In HSCT, transfusion was not related to the survival rate. However, overall survival rate is better in short interval between diagnosis and HSCT than in long interval (P< 0.05). There was no significant difference in the probability of transfusion independence according to treatment strategies, even though it was 71.0% in HSCT and 12.8% in immunosuppressive therapy at the end point of survey (P=0.47). The response pattern was as follows. There were 155 cases of complete response, 110 of partial response and 120 of no response in spite of various treatments. The relapse after treatment was found in 11 patients after IST, of which 6 patients experienced more than 2nd relapse. The median time between the end of treatment and relapse was 16 months (6~84 months). Only three cases developed into other diseases (1 case into acute myeloid leukemia and 2 cases into myelodysplastic syndrome). The median time from diagnosis to the end of treatment was 62 months (0.5~174 months). In fatal cases, the median time between diagnosis and death was 29 months (0~144 months) despite several therapeutic strategies. CONCLUSION: In Korea, the annual incidence of children with AA is 4.5 per million. This result is similar to the ones reported in other Asian countries, but higher than those in Western countries. Although a lot of children with AA received various therapies including IST or HSCT, new treatment strategies have to be developed to improve the survival rate and the quality of life of children with AA