Reliable assessment of faecal loading in older adults by abdominal radiograph

Objective: To produce a measure of faecal loading using plain abdominal radiograph that has both face validity and reliability. This formed part of the Ballarat Constipation Study, which aimed to establish a suite of objective assessment tools for the identification of constipation in residential and extended care facilities. Methods: A 20-point loading scale (five levels of loading × four segments of colon) was evaluated using 75 plain abdominal films of patients older than 65 years that were taken for various purposes. These were randomly ordered and five radiologists, following appropriate training, rated the films. Each was blinded to the others' responses. To establish intrarater reliability, each radiologist rated 25 of the films for a second time. Results: Reliability was assessed using Q-type correlations for raw scores and Cohen's kappa for dichotomised scores. Inter-rater correlations ranged from 0.57 confidence interval (CI) (0.38, 0.72) to 0.83 CI (0.74, 0.90). Inter-rater kappas ranged from 0.28 CI (0.06, 0.50) to 0.72 CI (0.50, 0.94). Intra-rater correlations ranged from 0.68 CI (0.38, 0.84) to 0.92 CI (0.82, 0.96) and intra-rater kappas ranged from 0.26 CI (- 0.08, 0.60) to 0.90 CI (0.70, 0.99). Conclusion: This method of assessing and reporting faecal loading in older people has an acceptable level of reliability for four of the five radiologists. The scale was considered appropriate for use in the larger study, where its validity was tested.