Epidemiology of aplastic anemia: a study of 1324 cases.

Objective: Prevalence of aplastic anemia (AA) is high in the Asian population. This study was done to explore the etiology and association of AA with various socio-economic and environmental factors. Study design and setting: Study included 1324 consecutive AA cases registered at Armed Forces Bone Marrow Transplant Centre Rawalpindi, Pakistan, from March 2001 to August 2016. The study questionnaire was completed through an interview. It included patients' socio-demographic details, personal and family medical history, environmental attributes and clinico-hematological features. Results: The median age of patients was 20 years, 997 were male and 327 female. Distribution of non-severe, severe and very severe AA was 230 (17.4%); 598 (45.2%) and 496 (37.4%), respectively. The majority of patients were from low ( n  = 761, 57.5%) or middle socioeconomic class ( n  = 543, 41%). Consanguinity among patients ( n  = 806, 61%) was slightly higher than the national statistics. History of chemical exposures included fertilizers ( n  = 116, 8.7%), pesticides ( n  = 56, 4.2%) and industrial chemicals ( n  = 37, 2.8%). PNH clone was found in 63 of AA patients. After excluding 298 patients undergoing HSCT and 660 deaths/lost to follow-up, disease evolution was observed in 38(10.4%) patients out of 366 evaluable patients. These included PNH = 18, MDS = 11 and AML = 9. Discussion: Due to lack of funding and adequate human resource at the center, age and sex-matched controls could not be included. Other limitations were a lack of molecular testing to exclude the possibility of inherited bone marrow failure syndromes on a genetic basis. Conclusion: Younger age, male predominance and higher consanguinity point toward genetic factors in AA etiology among the South Asian population.