A simple clinical index of Crohn's disease activity - the Cape by jlhd32


More Info
									 502     SAMT    DEEL 68    28 SEPTEMBER 1985

 A simple clinical index of Crohn's
 disease activity - the Cape Town index
J. P. WRIGHT,              I. N. MARKS,         A. PARFITT

 The assessment of disease activity in Crohn's disease is liable     Index correlated better with the HBI and CDAI but less well
 to observer error because of the predominance of subjective         with the van Hees index. The latter two indices did not
 symptoms such as frequent diarrhoea, abdominal cramps and           correlate well with each other. The addition of the erythrocyte
 lassitude. While this difficulty in assessment occurs when          sedimentation rate (ESR) to the Cape Town Index did not
 comparing different consultations by the same physician, it         improve its correlation with the CDAI (Table Ill).
 becomes more serious when comparing disease activity in
 different centres and particularly when performing therapeutic
drug studies.                                                        Discussion
    In 1976 the Crohn's Disease Activity Index (CDAI) was
 published.' This index required a 7-day documentation by the         Although the correlation of the Cape Town Index and the
patient of his or her symptoms including the exact diarrhoea          CDAI was not as high as we had expected, it was nevertheless
frequency. Four years later the no less complicated van Hees         similar to that obtained by the HBI when compared to the
 Index2 appeared. It usually required calculation by an electronic    CDAI. The latter correlation was however somewhat less than
calculator but had the advantage of including more objective          the 0,93 originally reported. J The reason for this is uncertain.
parameters such as serum albumin and haemoglobin values. It          The patients entered into our study reflect a 'normal' clinic
was also less patient-dependent; for example, bowel function          population assessed on 1 068 occasions over a IS-month period.
was simply assessed as being watery, semi-formed or formed.          This is a larger number than that reported by Harvey and
At the same time the simplified CDAI, the Harvey-Bradshaw            Bradshaw but should not account for the large difference.
Index (HBI), which quantified the patient's previous 24-hour            As the addition of the ESR to the index did not materially
symptoms, was described. J It had the avantage of easy calcu-        improve its correlation with the CDAI, it has not been included
lation but the disadvantage of being heavily biased by the           in the proposed index.
frequency of diarrhoea.                                                 In the development of the CDAI and van Hees indices a
   The need for a simple clinical index of disease activity          selection of clinical and laboratory parameters were chosen on
without single-parameter bias was discussed at a meeting of          the basis of clinical experience and subjected to analysis using
the International Organization for the study of Inflammatory         the physician's global assessment of the patient as the standard.
Bowel Disease held in Oxford during Wovember 1980. A                 The resulting index therefore best reflects the physician's
number of clinical and laboratory parameters were considered         opinion, using the parameters entered into the analysis. If the
but the overriding need for simplicity led to the formulation of     purpose of the index is to quantify the attending physician's
an index based on 10 parameters (9 clinical and 1 haemato-           opinion, then these complicated indices and their simplified
logical). It was suggested that the correlation between this         variants are adequate. Our view, however, is that 'activity
index and the established, more complicated indicies be              indices' should reflect more than this. In addition to the
examined in a prospective series of patients with Crohn's            clinical symptoms they should also reflect our understanding
disease. The present study was therefore undertaken using a          of 'active Crohn's disease'.
modification of the suggested index - the Cape Town Index               A patient with Crohn's disease may have marked diarrhoea
(Table I).                                                           and even lassitude for many reasons including bacterial over-
                                                                     growth and malabsorption as well as histologically active
                                                                     Crohn's disease. In the former, diarrhoea and lassitude may be
Patients and methods                                                 prominent, while in the latter local and systemic features are
                                                                     usually also present. The proposed index therefore ranks
Patients being seen by the authors as part of a prospective          diarrhoea occurring for instance 6 times a day as equivalent to
therapeutic tria14 were asked to complete diary cards in order       the presence of a local complication such as an anal fistula,
to calculate the CDAI. At each clinic visit they were assessed       while the CDAI scores this amount of diarrhoea IS times
by the authors and the HBI, van Hees, CDAI and Cape Town             higher than an anal fistula. The underlying problem is that it
indices were calculated.                                             is not known which of the various parameters measured best
  The correlation coefficient between each index and the P           reflect the underlying disease process and the likely_clinical
value was calculated.                                                course.
                                                                        The advantages of the Cape Town Index include the broad
                                                                     base of clinical features used, the heavier weighting given to
Results                                                              complications over diarrhoea, and the use of ranking rather
                                                                     than absolute values which are liable to miscalculation by
Eighty-six patients were seen on 1068 occasions. Most patients       patient and medical attendant alike.
had mild-to-moderate symptoms (Table ll). The Cape Town                 There is need for further study of the reliability and
                                                                     reproducibility of the proposed Cape Town and other published
                                                                     indices in quantifying symptoms and in assessing the underlying
Gastro-intestinal Clinic, Groote Schuur Hospital, and                disease process and concurrent clinical course in patients with
Department of Medicine, University of Cape Town                      Crohn's disease.
J. P. WRIGHT, M.B. CH.B., M.R.C.P.
I. T. MARKS, M.B. CH. B., F.R.C.P.
A. PARFIIT, S.RS.                                                      We acknowledge the support of the South African Medical
                                                                     Research Council and the Nellie Atkinson Trust.
                                                                                                                       SAMJ   VOLUME 68     28 SEPTEMBER 1985           503

                                                            TABLE I. CAPE TOWN INDEX DEFINITION
                                                                         0                                  2                   3
                     Diarrhoea                                                        ';;;4                 5                  ;;'6
                     Abdominal pain                                                   Mild                  Moderate           Severe
                     Well-being                                                       Below par             Unwell             Terrible
                       Local                                                          Skin tag              Sinus               Fistula
                       Systemic                                                       Stomatitis            Arthralgia          Arthritis
                                                                                                                                Erythema nodosum
                       Temperature (0C)                               ';;;37,0        ';;;38,0              ';;;39,0            >39,0
                     Weight compared with
                     last weight                                                                            <95%                <90%
                       Mass                                                                                 Indefinite          Certain
                       Tenderness                                                     Mild                  Moderate            Severe
                     Haemoglobin (g/dl)                               ;;'12,0         <12,0                 <11,0               <10,0
                     (ESR (mm/1st h)                                   ';;;15         >15                   >25                 >40t)
                     -The index is calculated by adding the score for each period. thus obtaining a value between 0 and 30.
                     TAdded to test the effect of a commonly used indicator of inflammation but not included in proposed index.

                                                     TABLE 11. VALUES OF INDICES STUDIED (N= 1068)
                                                                       Mean                         SO            Minimum           Maximum
                          Cape Town                                      2,8                      2,8                   o                  17
                          Cape Town + ESR                                3,65                     3,2                   o                  19
                          HBI                                            2,2                      2,9                   o                  23
                          COAl                                          85                       68                    14                 433
                          Van Hees Index                               168                       32                    77                 329

                                    TABLE Ill. CORRELATION MATRIX OF THE INDICES STUDIED (N= 1 068)*
                          Cape Town                                    0,374
                          Cape Town        + ESR                       0,481                 0,934
                          COAl                                         0,418                 0,761                0,728
                          HBI                                          0,262                 0,810                0,733                0,745
                                                                     Van Hees              Cape Town            Cape Town              COAl
                                                                                                                  + ESR
                          "'The probability value of all the correlation coefficients is < 0.001.

REFERENCES                                                                                          index of inflammatory activity in patients with Crohn's Disease. Gm 1980;
                                                                                                    21: 279-280.
L Best WR, Bectel JM, Singleton JW, Kern F jun. Development of a Crohn's                         3. Harvey RF, Bradshaw JM. A simple index of Crohn's disease activity.
   Disease Activity Index - National Crohn's Disease Study. Gaslroenrerology                        La"cer 1980; i: 534.
   1976; 70: 439-444.                                                                            4. Wright JP, Mee AS, Parfirr A er al. vitamin a therapy in patients with
2. Van Heese PAM, Van Elteren P T, Van Lier NJJ, Van Tongeren JHM. An                               Crohn's disease. Gasrroemerology 1985; 88: 512-514.

To top