Greater improvements in most QoL and symptom severity measurements were observed in children randomized to undergo adenotonsillectomy , including the parent-completed Pediatric Quality of Life inventory ( effect size [ ES ] : 0.37 ) , the 18-item Obstructive Sleep Apnea QoL instrument ( ES : -0.93 ) , the modified Epworth Sleepiness Scale score ( ES : -0.42 ) , and the Sleep-Related Breathing Scale of the Pediatric Sleep Questionnaire ( ES : -1.35 ) .