MMPI-2 and MMPI-2-Restructured Form Validity Scales: Complementary Approaches to Evaluate Response Validity

Waddell non-organic signs: new evidence suggests somatic amplification among outpatient chronic pain patients

BACKGROUND CONTEXT

Waddell et al. identified a set of eight non-organic signs in 1980. There has been controversy about their meaning, particularly with respect to their use as validity indicators.

PURPOSE

The current study examined the Waddell signs in relation to measures of somatic amplification or over-reporting in a sample of outpatient chronic pain patients. We examined the degree to which these signs were associated with measures of over-reporting.

STUDY DESIGN/SETTING

This study examined scores on the Waddell signs in relation to over-reporting indicators in an outpatient chronic pain sample.

PATIENT SAMPLE

We examined 230 chronic pain patients treated at a multidisciplinary pain clinic. The majority of these patients presented with primary back or spinal injuries.

OUTCOME MEASURES

The outcome measures used in the study were Waddell signs, Modified Somatic Perception Questionnaire, Pain Disability Index, and the Minnesota Multiphasic Personality Inventory-2 Restructured Form.

METHODS

We examined Waddell signs using multivariate analysis of variance (MANOVA) and analysis of variance (ANOVA), receiver operating characteristic analysis, classification accuracy, and relative risk ratios.

RESULTS

Multivariate analysis of variance and ANOVA showed a significant association between Waddell signs and somatic amplification. Classification analyses showed increased odds of somatic amplification at a Waddell score of 2 or 3.

CONCLUSIONS

Our results found significant evidence of an association between Waddell signs and somatic over-reporting. Elevated scores on the Waddell signs (particularly scores higher than 2 and 3) were associated with increased odds of exhibiting somatic over-reporting.