Abstract
BACKGROUND: Sudden gains (rapid, large, stable improvements in symptoms) are common in psychological therapy and are associated with favourable outcomes, but no studies have investigated sudden gains in children and young people (CYP) with a chronic physical condition. METHODS: Within-group study nested in the Mental Health Intervention for Children with Epilepsy (MICE) randomised trial of modular cognitive-behavioural therapy for CYP with epilepsy, utilising goal-based outcomes (GBOs) and standardised session-by-session measures (including the brief parental self-efficacy scale and Strengths and Difficulties Questionnaire [SDQ] session-by-session measure). The occurrence and potential predictors of sudden gains, and the association of sudden gains with outcomes at final session and follow-up were investigated using multivariable logistic and linear regression. RESULTS: Among 147 participants (mean age: 10.4 years, 49% female) and across nine measures, 39% experienced between two and four sudden gains, most frequently on the mean GBO (occurrence, 44.9%). Characteristics such as intellectual disability, pretreatment scores and the number of sessions received were associated with significantly greater odds of sudden gains in some measures, whereas nonwhite ethnicity and nonemployment of the primary caregiver were associated with reduced odds. Sudden gains were associated with favourable final-session scores for mean GBO (GBO, adjusted mean difference [aMD]: 0.9, 95% CI: 0.3 to 1.6, p = .004, D = 0.63), parental self-efficacy (aMD: 1.2, 95% CI, 0.1 to 2.4, p = .027, D = 0.37) and the SDQ session-by-session measure (aMD: -1.7, 95% CI, -3.0 to -0.3, p = .014, D = -0.44), but not with 6-month adjusted SDQ total difficulties scores. CONCLUSIONS: Sudden gains were common in this population, occurring most frequently on personalised measures, and were associated with favourable final-session scores. Personalised measures taken at each session with a focus on sudden gains may be a useful adjunct to treatment. Future research and clinical practice should investigate how to increase the occurrence of sudden gains in CYP with long-term conditions receiving psychological therapy.