Validity and generalizability of the Withdrawal Assessment Tool-1 (WAT-1) for monitoring iatrogenic withdrawal syndrome in pediatric patients

Critically ill pediatric patients frequently receive prolonged analgesia and sedation to provide pain relief and facilitate intensive care therapies. Iatrogenic withdrawal syndrome occurs when these drugs are stopped abruptly or weaned too rapidly. We investigated the validity and generalizability of the Withdrawal Assessment Tool-1 (WAT-1) in children during weaning of analgesics and sedatives. Of 308 children initially supported on mechanical ventilation for acute respiratory failure, 126 (41%) from 21 centers (median age 1.6 years; interquartile range 0.6-7.7 years) were exposed to 5 or more days of opioids. Subjects were assessed for withdrawal symptoms with the WAT-1, an 11-item (12-point) scale, from the first day of weaning from analgesia/sedation until 72 h after the last opioid dose. A total of 836 daily WAT-1 assessments were completed, with a median (interquartile range) WAT-1 score of 2 (0-4) over 6 (3-9) days per subject. There were no significant differences in WAT-1 scores as a function of age. Factor analyses confirmed that motor-related symptoms and behavioral state accounted for the most variance in WAT-1 scores. Supporting construct validity, cumulative opioid exposures were greater [40.2 (19.7-83.4) vs 17.6 (14.6-39.7) mg/kg, P=.004], length of opioid treatment before weaning was longer [7 (6-11) vs 5 (5-8)days, P=.004], and length of weaning from opioids was longer [10 (6-14) vs 6 (3-9)days, P=.008] in subjects with WAT-1 scores of ≥ 3 compared to subjects with WAT-1 scores of <3. The WAT-1 shows good psychometric performance and generalizability when used to assess clinically important withdrawal symptoms in pediatric intensive care and general ward settings.