Objective: To assess the effect of dependent personality disturbance as an influence on the cost and clinical outcome of health anxiety.
Method: In the course of a randomized trial of treatments for patients with high health anxiety over 12 months, we also recorded dependent personality status by two methods: the Personality Assessment Schedule (an observer-rated instrument) and the self-rated Dependent Personality Questionnaire (DPQ), the latter being administered at baseline, six months and 12 months. The two main hypotheses tested were that patients with dependent personality features would have a worse outcome and attract greater health service costs.
Results: Forty-nine patients took part in the trial; all had baseline dependent personality data, 44 provided health service costs, and 38 had observer-rated personality assessments. At baseline patients with any personality disorder had higher clinical ratings for health anxiety, and dependent personality disturbance, mainly in the form of personality difficulty, was associated with a worse outcome than those without dependent personalities after correction for baseline differences. The DPQ at a score of 15 successfully identified all patients with dependent personality disorder in both ICD and DSM classifications and showed a significant but relatively modest reduction in scores of 1.5 (13%) during the course of the 12-month trial. Costs in those separated by personality status showed those with dependent personality incurred 45% more health service costs than those without these personality characteristics (p = .10). No patient with dependent personality disorder dropped out of treatment compared with 6 out of 38 (16%) of those with no dependence.
Conclusions: The DPQ is probably a reliable instrument for assessing dependent personality characteristics without the need for interview and its scores, unlike many ratings of personality, are stable over time. The findings may have been influenced by different responses to those treated in the trial with cognitive behaviour therapy compared with control treatment.