Analysis
The Pediatric PROMIS-25 measured six HRQoL domains (Mobility, Anxiety,
Depressive Symptoms, Fatigue, Peer Relationships, Pain Interference) by
asking four questions per domain using a five-point Likert scale (e.g.,never, almost never, sometimes, often, almost always ; or,with no trouble, with a little trouble, with some trouble, with a
lot of trouble, not able to ). Additionally, a single-item PROMIS Pain
Intensity item was measured on a scale of 0 to 10. All items have a
7-day recall period.
Within each domain, a raw score was calculated as the sum of the answers
to the four question items. Raw scores were transposed to standardized
domain T-scores using tables provided by the PROMIS scoring manual, with
a mean of 50 and standard deviation of 10.31 The
PROMIS standardized T-score is composed from a mixed calibration sample
of United States children in good health and children with a wide range
of chronic conditions.32 Higher PROMIS scores for
Mobility and Peer Relationships reflect better functioning and
relationships, with scores < 40 (1 standard deviation (SD)
below the mean) considered fair to poor.33 Higher
symptom scores reflect worse symptom experiences (Anxiety, Depressive
Symptoms, Fatigue, Pain Interference), with scores > 55 (1
SD above the mean) indicating moderate to severe symptom
burden.33
Differences between diagnosis, active treatment, and follow-up domain
mean T-scores were compared to published minimally important difference
(MID) estimates of 2-3 points, and also analyzed using an ANOVA
test.34 For sensitivity analyses, parent
proxy-reported surveys were removed, as it has been demonstrated that
caregivers consistently overestimate symptoms and underestimate function
relative to child self-reports.35
Cohort characteristics were summarized using simple descriptive
statistics. Patients were followed from enrollment until death, LTFU, or
administrative censoring on January 31, 2020. We conducted an
exploratory analysis to compare outcomes among patients with outcomes
for those with poor versus adequate HRQoL domain scores. Kaplan-Meier
methods were used to estimate overall survival and risk factors for
mortality were assessed using univariate Cox proportional-hazards
regression analysis to estimate hazard ratios (HR) of quantitative
predictor variables. Analyses were conducted using R 3.5.2 (New York,
New York).