Dimensions of dependence and their influence on the outcome of cognitive behaviour therapy for health anxiety: randomised controlled trial

Abstract

Background: The personality trait of dependence is somewhat difference from many others in that it is often regarded as adaptive and, when maladaptive, is of less pathological significance than many other traits. There is also some evidence that it may be a positive trait in health seeking behaviour. We therefore examined its impact in a large randomised controlled trial of psychological treatment for health anxiety. Aims: To test whether dependent personality traits were positive or negative in determining the outcome of an adapted form of cognitive behaviour therapy for health anxiety (CBT-HA) over their otv ce erh the hypotheses that personality dysfunction recorded using the new ICD-11 diagnostic system had a negative influence on the outcomes of treatment with cognitive behaviour therapy for health anxiety over 2 years and that personality dysfunction would be associated with increased cost. Method: Personality dysfunction was assessed at baseline in a randomised controlled trial of 444 patients from medical clinics with pathological health anxiety treated with a modified form of cognitive behaviour therapy for health anxiety (CBT-HA) or standard treatment in the medical clinics, with assessment on four occasions over 2 years. Personality dysfunction was assessed at baseline using a procedure that led to five ICD-11 proposed groups (0 = no personality dysfunction, 1 = personality difficulty, 2 = mild personality disorder, 3 = moderate personality disorder, 4 = severe personality disorder). The statistical analysis used a mixed model with the primary outcome as change in health anxiety scores after one year. Total costs over follow-up were calculated from service use and hospital data and compared by personality group. Results: In total, 381 patients (86%) had some personality dysfunction with 184 (41%) satisfying the ICD criteria for personality disorder. Those with no personality dysfunction showed no difference in health anxiety response to CBT compared with standard care (P=0.90) and showed worse social function (P<0.03) whereas those with any form of personality dysfunction derived significant benefit from CBT-HA maintained over two years (P<0.001) with lesser benefit in those with more severe personality disorders (P<0.05) There was slight evidence that costs were relatively higher in participants with moderate and severe personality disorder with CBT-HA and lower with less personality pathology. Conclusion: The results suggest that anxiety disorders in the absence of personality dysfunction do not require specific psychological treatment and that personality abnormality is not a bar to success with CBT in this population.