Health outcomes
Physical health outcomes. Clinically-assessed health conditions were evaluated during on-campus medical evaluations and defined using modified Common Terminology Criteria for Adverse Events (CTCAE) version 4.03 criteria adapted for childhood cancer survivors.21 Comprehensive medical assessments included diagnostic procedures, an assessment of neuromuscular function, and a physical evaluation with a standardized laboratory battery. At the time of assessment, if survivors reported any chronic health conditions previously diagnosed, medical records were obtained to validate these diagnoses. The following organ systems were evaluated during the medical assessment and included as outcome variables: cardiac, pulmonary, renal, endocrine, gastrointestinal/hepatic, neurologic and musculoskeletal. CTCAE grades range from 1-4 (mild [grade 1], moderate [grade 2], severe or disabling [grade 3], life-threatening [grade 4]), and adverse health conditions were defined as grade ≥2 for each condition (i.e. moderate to life threatening). Supplemental Tables S2a-g present the frequency of grade 2-4 conditions for study participants, classified by each organ system. Chronic health conditions were included if they were diagnosed prior to and up to three months following the sleep assessment.
In addition to evaluating health conditions by each organ system, we created a composite measure assessing the burden/severity of the survivor’s physical health. A method developed by Geenen et al.22 was employed to aggregate chronic health conditions across organ systems (cardiovascular, pulmonary, endocrine, neurologic, gastrointestinal, musculoskeletal, and renal), taking into account the frequency and grade of conditions. For survivors who had multiple chronic health conditions within the same organ system, the highest grade within that organ system was utilized. This chronic health burden score was classified via the following categories: none, low (only grade 1 events), medium (having ≥1 grade 2 event and/or 1 grade 3 event), high (having ≥ 2 grade 3 events or 1 grade 4 event and at most 1 grade 3 event), and severe (>1 grade 4 events or ≥ 2 grade 3 events and 1 grade 4 event).
Psychological health outcomes. The Brief Symptom Inventory-18 (BSI-18)23 was administered at the time of the participant’s sleep evaluation to assess clinically significant anxiety and depression. Using sex-specific normative data, survivors with a T-score ≥63 (90th percentile) on either subscale were classified with clinically significant anxiety and/or depression. The BSI-18 has been previously validated in childhood cancer survivors.24