Socioeconomic Status, Diagnostic Interval Length and Outcome in Pediatric Acute Lymphoblastic Leukemia

Efforts to determine the causes of treatment failure in acute lymphoblastic leukemia (ALL), the most common childhood cancer, have neglected the potential role of socioeconomic status (SES). This thesis aimed to address three key knowledge gaps in the field of SES and pediatric oncology. First, we evaluated the current literature by conducting a systematic review of studies evaluating the impact of SES upon childhood cancer survival. Of the 36 studies identified, we found that low SES was uniformly associated with inferior outcome in low- and middle-income countries. The same association was commonly found in studies conducted in high-income countries. Secondly, as several researchers have proposed that prolonged diagnostic intervals (time between first healthcare access and diagnosis) may serve as a pathway linking low SES and inferior cancer outcome, we developed and validated a novel measure of diagnostic interval length among Ontario children with ALL using population-based health services data. Using this measure, we found that prolonged diagnostic interval (≥4 days) was associated with having a general practitioner (GP) as primary care physician vs. a pediatrician [adjusted odds ratio (OR) 1.60, 95% confidence interval (CI) 1.04-2.47; p=0.03]. Socioeconomic and healthcare access variables were not associated with interval length. While prolonged diagnostic intervals were associated with superior event-free survival [hazard ratio (HR) 0.71, 95% CI 0.52-0.98; p=0.04], this association was confounded by disease biology. Finally, we aimed to determine the impact of SES upon Ontario children with ALL. We found that while low SES was not associated with inferior EFS, immigrant status was associated with superior outcome (HR 0.36, 95% CI 0.13- 0.96; p=0.04). These findings have important implications for patients, caregivers, researchers and policymakers. Future studies should use the methodologies developed in this thesis to explore the impact of SES and diagnostic interval length in other malignanciesPh.D.2017-06-17 00:00:0