Socioeconomic disparities in survival from childhood leukemia in the United States and globally : a meta-analysis

Background: Despite advancements in the treatment of childhood leukemia, socioeconomic status (SES) may potentially affect disease prognosis. This study aims to evaluate whether SES is associated with survival from childhood leukemia. Methods: The US National Cancer Institute Surveillance, Epidemiology and End Results Program (SEER) 1973-2010 data were analyzed; thereafter, results were meta-analyzed along with those from survival (cohort) studies examining the association between SES indices and survival from childhood leukemia (end-of-search date: 31 March 2014). Randomeffects models were used to calculate pooled effect estimates (relative risks, RRs); meta-regression was also used. Results: We included 29 studies yielding 28 804 acute lymphoblastic leukemia (ALL), 3208 acute myeloblastic leukemia (AML) and 27 650 'any' leukemia (denoting joint reporting of all subtypes) cases. According to individual-level composite SES indices, children from low SES suffered from nearly twofold higher death rates from ALL (pooled RR: 1.83, 95% confidence interval 1.00-3.34, based on four study arms); likewise, death RRs derived from an array of lower area-level SES indices ranged between 1.17 and 1.33 (based on 11 study arms). Importantly, the survival gap between higher and lower SES seemed wider in the United States, with considerably (by 20%-82%) increased RRs for death from ALL in lower SES. Regarding AML, poorer survival was evident only when area-level SES indices were used. Lastly, remoteness indices were not associated with survival from childhood leukemia. Conclusion: Children with lower SES suffering childhood leukemia do not seem to equally enjoy the impressive recent survival gains. Special health policy strategies and increased awareness of health providers might minimize the effects of socioeconomic disparities.