Abstract
BACKGROUND: Proponents of clinical case formulations argue that the causes and mechanisms contributing to and maintaining a patient's problems should be analysed and integrated into a case conceptualization, on which treatment planning ought to be based. Empirical evidence shows that an individualized treatment based on a case formulation is at least sometimes better than a standardized evidence-based treatment. METHODS: We argue that it is likely to improve decisions when two conditions hold: (a) knowing about the mechanisms underlying the patient's problems makes a difference for treatment, and (b) the case formulation is based on valid knowledge about mechanisms of psychopathology. RESULTS: We propose a protocol for assessment, case formulation and treatment planning (PACT), which incorporates transdiagnostic accounts of psychopathology. PACT describes a 5-step decision making process, which aims to help clinicians to decide when to resort to evidence-based treatments and when to construct a case formulation to individualize the treatment. CONCLUSION: We show how PACT works in practice by discussing treatment planning for a clinical case involving symptoms of social anxiety, depression and post-traumatic stress disorder.