Sudden gains in routine clinical care: application of a permutation test for trauma-focused cognitive behavioural therapy

Background: Sudden gains, defined as large and stable improvements of psychopathological symptoms, are a ubiquitous phenomenon in psychotherapy. They have been shown to occur across several clinical contexts and to be associated with better short-term and long-term treatment outcome. However, the approach of sudden gains has been criticized for its tautological character: sudden gains are included in the computation of treatment outcomes, ultimately resulting in a circular conclusion. Furthermore, some authors criticize sudden gains as merely being random fluctuations.Objective: Use of efficient methods to evaluate whether the amount of sudden gains in a given sample lies above chance level.Method: We used permutation tests in a sample of 85 patients with posttraumatic stress disorder (PTSD) treated with trauma-focused cognitive behaviour therapy in routine clinical care. Scores of self-reported PTSD symptom severity were permuted 10.000 times within sessions and between participants to receive a random distribution.Results: Altogether, 18 participants showed a total of 24 sudden gains within the first 20 sessions. The permutation test yielded that the frequency of sudden gains was not beyond chance level. No significant predictors of sudden gains were identified and sudden gains in general were not predictive of treatment outcome. However, subjects with early sudden gains had a significantly lower symptom severity after treatment.Conclusions: Our data suggest that a significant proportion of sudden gains are due to chance. Further research is needed on the differential effects of early and late sudden gains. Treatment-related sudden gains exhibit clinical significance when their manifestation is above chance level.We used permutation tests to examine their occurrence in trauma-focused cognitive behaviour therapy as applied in a naturalistic treatment setting.The occurrence of sudden gains in general was not significantly higher than chance, yet early sudden gains were associated with improved treatment outcome. Antecedentes: Los progresos subitos, definidos como mejorias amplias y estables en los sintomas psicopatologicos, son un fenomeno ubicuo en las psicoterapias. Se ha demostrado que suceden en diferentes contextos clinicos y que estan asociados a mejores respuestas al tratamiento al corto y al largo plazo. Sin embargo, el abordaje de los progresos subitos ha sido criticado por su caracter tautologico: Los progresos subitos estan incluidos en el calculo de los resultados de los tratamientos, lo que resulta en una conclusion circular. Ademas, algunos autores realizan la critica que los progresos subitos no son sino meras fluctuaciones debidas al azar.Objetivo: Usar metodos eficientes para evaluar si la cantidad de progresion subita en una muestra determinada esta por encima del punto de corte atribuido al azar.Metodo: Empleamos pruebas de permutacion en una muestra de 85 pacientes con el diagnostico del trastorno de estres postraumatico (TEPT) en tratamiento con terapia cognitiva conductual centrada en el trauma en la atencion clinica de rutina. Los puntajes de severidad de las escalas clinicas autorreportadas para TEPT fueron permutadas 10.000 veces entre las sesiones y entre los participantes para recibir una distribucion aleatoria.Resultados: En conjunto, 18 participantes mostraron un total de 24 progresos subitos dentro de las primeras 20 sesiones. Las pruebas de permutacion mostraron que la frecuencia de los progresos subitos no se encontraba mas alla del punto de corte atribuido al azar. Se identificaron predictores no significativos de progreso subito, y el progreso subito en general no fue predictor del resultado del tratamiento. Sin embargo, los sujetos con progresos subitos tempranos obtuvieron significativamente una menor severidad en los sintomas luego del tratamiento.Conclusiones: La informacion sugiere que una proporcion significativa de progresos subitos son debidas al azar. Se necesita mas investigacion en la diferenciacion de los efectos de los progresos subitos tempranos y tardios.