191

Pain, 46{1991) 191-193 0 1991 Elsevier Science Publishers B.V. 0304-3959/91/$03.50 ADONIS 030439599100174M

PAIN 01830

A possible indicator of functional pain: poor pain scale correlation Franklin Perry, Philip H. Heller and Jon D. Levine Departments

of Anatomy.

Medicine,

and Oral und Maxillofacial

Surgety,

and Dil,isiotl

94143-0724

(U.S.A.

of Neurosciences,

Vnii’ersity

of California,

San Francisco,

CA

J

(Received 1 May 1990, revision received 26 November 1990, accepted 15 January 1991)

We studied correlations of pain measures in patients with either inflammatory bowel disease (IBD), Summary a disease with a clear organic cause, or irritable bowel syndrome (IBS), a functional pain syndrome in which there is little demonstrable pathology. Correlations were determined between measures on the visual analogue scale (VA9 and on the McGill Pain Questionnaire (MPQ). The VAS score and present pain intensity scale (PPI) of the MPQ correlated well in the organic IBD but correlated poorly in the functional IBS. Differences in correlation between the VAS and PPI scores in functional versus organic disease did not appear to be due to altered sensory and affective pain components. This finding is similar to what we observed in our previous study of organic and functional pain syndromes in the musculoskeletal system. Correlations between the other measures are also discussed. Key words: Inflammatory scale

bowel disease; Irritable bowel syndrome; McGill Pain Questionnaire;

Introduction In a recent publication we reported differences in the correlation of pain measurement in patients suffering from chronic pain of inffammato~ arthritis and in patients with primary fibrosis, a chronic pain syndrome with minimal or no demonstrable histopathology [3]. Data from patients with inflammatory arthritis (organic pain) revealed a large positive correlation between scores on different pain measures, while data from patients with fibrositis demonstrated a significantly lower correlation between the same measures. In particular for arthritis there was good correlation between the visual analogue scale (VAS), the most commonly used numerical scale for rating pain intensity [4,5], and the present pain index (PPI) subscale of the McGill Pain Questionnaire (MPQ) fl]. There was no correlation between the VAS and PPI in patients with fibrositis.

Corres~nde~ce to: Dr. Jon D. Levine, Division of Rheumatology, U-426 (Box 07241, University of California at San Francisco, San Francisco, CA 94143.0724, U.S.A.

Visual analogue

In the present study we have compared, in a similar context, organic and functional pain syndromes involving the gastrointestinal system. The 2 study groups are comprised of patients with inflammatory bowel disease (IBD), an organic disease, and patients with irritable bowel syndrome (IBS), a functional syndrome. As in the case of musculoskeletal syndromes, we found good correlation between the VAS and PPI in patients with organic disease but no correlation in patients with functional disease. Correlations between other pain measures are also reported.

Methods Patients were recruited from the Gastroenterolo~ Clinic and from a private practice at the Univ. of California in San Francisco. Patients were approached and, if they agreed, were interviewed during a regular clinic visit. The study population consisted of 33 patients reporting pain at the time of the study who were diagnosed by their attending physician as having either inflammatory bowel disease (IBD, ‘organic’ group with ulcerative colitis or Crohn’s disease) or irritable bowel

syndrome (IBS, ‘functional’ group). Patients with other active major medical problems were exchtded from the study. The ‘organic‘ IBD group consisted of 21 patients (9 male. 12 female) with a mean age of 46.8 years; the ‘functional’ IBS group consisted of 12 patients (3 male, 9 female) with a mean age of 36.0 years. Since a variety of drugs are used to treat these conditions. making interpretation of any drug effect very difficult. specific drug histories wcrc not obtained. We have assumed that our analysis of correlations still provides useful information in terms of the specific disease. The experimental protocol was approved by the UCSF Committee on Human Research. Measures of pain were obtained using a 10 cm visuat analog scale (VAS) and the McGill Pain Questionnaire (MPQ). The VAS scores were obtained by asking patients to place a single vertical mark on a horizontal line at a point corresponding to their current pain intensity; the VAS was anchored on the left end with the words ‘no pain’ and on the right end with the words ‘worst pain imaginable.’ Because a current pain VAS was used, therefore, the VAS level might differ from a time-averaged value (such as a 24 h VAS), since IBS and IBD pain can vary and depend on other factors such as recency of food intake. Nevertheless. current pain reports can be considered a valid source for the study of the correlations of pain measures. The MPQ was administered as previously described [ll. Patients located their pain on a body diagram. choosing not more than 1 pain descriptor from each of 20 categories each of which consisted of 2-h words (written and read aloud), and they indicated present pain intensity (PPI) on a S-point scale (mild, discomforting, distressing, horrible, excruciating). Separate sensory and affective pain rating index scores (PRI-S and PRI‘4, respectively) were obtained using the weighted-rank method [2]. Statistical comparisons between groups were performed using Student’s t test with the I’ < 0.05 level taken as significant.

Results Mean pain ratings of patients with IBD and IBS are shown in Table 1. There are no significant differences in pain rating between the 2 groups. No differences were found in the number of words chosen (NWC) or the number of body areas (NBAI marked as painful on a body diagram. The ratio of females to males was greater in the IBS than in the IBD group. However, there were no significant differences by gender on any of the measured variables. Correlations between the VAS and the MPQ subscales for the IBD group are displayed in Table II. The 2 numerical scores, the VAS and the PPI scale of the MPQ, correlated highly (I = 0.75, P < 0.0011. The sen-

TABLE

I

PAIN RATINGS ON VAS AND MPQ SUBSCALtr. 2 GROUPS OF CHRONIC PAIN PATIENTS

Pain scale

IBD

IBS

-.-.7.3 (0.5 1

l’izs

SCORES

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FOR

.._ __...

2.h(0.X)

MPO I. 1 (0.b) 16.1 (1.3) 5.X(I.O) II).X t 1.11) 5.6 (0.0)

PPI PRI-S PRI-A NW

A possible indicator of functional pain: poor pain scale correlation.

We studied correlations of pain measures in patients with either inflammatory bowel disease (IBD), a disease with a clear organic cause, or irritable ...
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