Comparison of the Constipation Assessment Scale and plain abdominal radiography in the assessment of constipation in advanced cancer patients.

CONTEXT Constipation is a distressing condition for advanced cancer patients and is frequently underdiagnosed. OBJECTIVES The primary objective of this study was to determine if a strong correlation existed between the use of the Constipation Assessment Scale (CAS) and a plain abdominal radiograph in the interpretation of constipation in patients with advanced cancer. The secondary aim of the study was to compare the plain film radiographic constipation scores among three palliative medicine physicians. METHODS The study was a prospective cross-sectional study of 50 advanced cancer patients admitted to a tertiary palliative care unit. These patients completed the CAS shortly after their admission to the unit. Around the same time, they underwent a flat plate of abdomen that was scored from 0 to 12, based on the amount of stool in the colon, by three palliative medicine physicians who were blinded to the CAS results and each other's radiographic interpretations. Kendall Tau correlation coefficient was used to estimate and test the correlations between the CAS and radiographic constipation scores. RESULTS There was no concordant correlation between the CAS scores and each physician's radiographic constipation score. There also was no concordant correlation between the CAS score and the combined radiographic constipation scores of the three palliative medicine physicians (Kendall Tau coefficient=0.04; P=0.72). The degree of correlation between the radiographic constipation scores from the three palliative medicine physicians was moderate. CONCLUSION Our study failed to yield a strong correlation between the CAS and the plain abdominal radiographic scores for constipation completed by three palliative medicine physicians. It is advisable that constipation in advanced cancer patients be assessed both clinically and radiographically.