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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 Score* 0 2 3 Diarrhoea ';;;4 5 ;;'6 Abdominal pain Mild Moderate Severe Well-being Below par Unwell Terrible Complications Local Skin tag Sinus Fistula Systemic Stomatitis Arthralgia Arthritis Iritis Erythema nodosum Temperature (0C) ';;;37,0 ';;;38,0 ';;;39,0 >39,0 Weight compared with last weight <95% <90% Abdominal 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.
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