Validity and clinical utility of distinguishing between DSM-5 somatic symptom disorder and illness anxiety disorder in pathological health anxiety: Should we close the chapter?

OBJECTIVE

To investigate the validity and clinical utility of distinguishing between DSM-5 somatic symptom disorder (SSD) and illness anxiety disorder (IAD) in pathological health anxiety: the excessive and recurrent fear of, or preoccupation with, having or developing a serious health condition.

METHODS

We compared SSD to IAD in pathological health anxiety (N = 334) with regard to concurrent, antecedent, and predictive validators. This was primarily a cross-sectional study, though we studied the effect of CBT longitudinally. Because we were interested in the discriminatory value of SSD and IAD over and above trait health anxiety, we used trait health anxiety as a covariate.

RESULTS

SSD (68%; 228/334) vs. IAD (32%; 106/334) differences were mostly non-significant and small in sociodemographics, core clinical characteristics, apparent course, etiological attribution, and physician visits (gs = -0.18-0.20; RRs = 0.84-1.09; IRRs = 0.87-0.99). However, SSD was associated with a significantly higher somatic symptom burden (gs = 0.20-0.72), more psychologist visits (IRR = 2.02, 95% CI: 1.24-3.28), and slightly higher disability (g = 0.22, 95% CI: 0.03-0.42). There was no significant difference in symptom reduction during CBT (g = -0.16, 95% CI: -0.37-0.05).

CONCLUSION

Although not all differences between SSD and IAD in pathological health anxiety seem to be explained by the level of trait health anxiety, the SSD vs. IAD distinction appears to convey little useful information in pathological health anxiety. Tentatively, considering the well-documented clinical characteristics and effective clinical interventions, it is probably most helpful to regard pathological health anxiety as a de facto anxiety or perhaps obsessive-compulsive spectrum disorder, regardless of the DSM-5 diagnosis of SSD or IAD.