Introduction
In 1980, Waddell et al. [1] developed a systematic collection of eight physical signs (widely referred to as Waddell signs) thought to measure non-organic subjective pain complaints centered around the lower back and extremities. These signs, reflective of pain complaints, did not have an organic etiology and were originally proposed to objectively predictwhether a patient would be a successful back surgery candidate. Waddell et al. proposed that the signs might reduce lengthy and costly referrals for psychological testing, which is sometimes used to identify poor surgical candidacy [1]. Fishbain et al. [2] reviewed 61 studies involving the Waddell signs and summarized the literature at the time. The authors found consistent evidence that the non-organic signs demonstrated acceptable inter-rater reliability, were associated with poorer surgical treatment outcomes, and predicted prolonged non-return to work.
The utility of Waddell signs as indicators of symptom feigning has been debated since their introduction, and some have pointed out that the signs are abused by physicians to discredit the validity of patients' complaints [3]. Fishbain et al. [4] concluded that Waddell signs were not representative of secondary gain and malingering because they were not consistently associated with medicolegal or workers' compensation status and improved with treatment. Fishbain et al. found mixed results as to whether Waddell scores were related to physicians' perception of dishonesty. Fishbain et al. also discussed three studies that found no association between Waddell signs and Minnesota Multiphasic Personality Inventory (MMPI)/Minnesota Multiphasic Personality Inventory-2 (MMPI-2) validity scales, thus supporting their claim that the signs were not representative of symptom over-reporting [1], [5], [6]. However, the three studies that examined the Waddell and MMPI/MMPI-2 validity scales limited their investigation to the three original validity indicators on the test: L, F, and K. Two of these scales (L and K) are measures of under-reporting and would therefore not be expected to show any significant association with Waddell signs. The F scale of the MMPI and MMPI-2 measures feigned psychopathology and, as such, would be unlikely to capture over-reporting of somatic and pain symptoms [7], [8].
The current study examined the Waddell signs in a sample of chronic pain patients treated at an outpatient multidisciplinary clinic. The majority of these patients had external incentives in the form of disability involvement and seeking narcotic pain medication, which is another secondary gain issue common in this type of setting. Scores on the Waddell signs were compared with various self-report indicators of over-reporting (both somatic and psychological symptoms), as well as systematic assessment of psychological, somatic, and pain variables. We hypothesized that individuals receiving higher scores on the Waddell signs would show evidence of somatic and pain over-reporting. We examined Waddell scores in relation to the latest version of the MMPI, the Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF) [9], which includes two validity scales specifically designed to assess non-credible somatic complaints, the Infrequent Somatic Responses (Fs) and Symptom Validity (FBS-r) scales, as well as two brief self-report measures of somatic and pain perception, the Modified Somatic Perception Questionnaire (MSPQ) [10] and the Pain Disability Index (PDI) [11], both of which have been shown to be effective in capturing amplification of somatic symptoms and pain [12], [13], [14].
