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Table 2 Binary recoding schema of the SCCAI for IRT analysis

From: Using item response theory (IRT) to improve the efficiency of the Simple Clinical Colitis Activity Index (SCCAI) for patients with ulcerative colitis

Items

SCCAI Scorea

Binary score

Item 1

Daytime frequency

0

0

1–3

1

Item 2

Nocturnal frequency

0

0

1–2

1

Item 3

Urgency

0–1

0

2–3

1

Item 4

Blood in stool

0

0

1–3

1

Item 5

General well-being

0–1

0

2–4

1

Item 6

Extra-intestinal manifestations

Arthritis (new Item 6)

Yes/no

1/0

Uveitis (new Item 7)

Yes/no

1/0

Erythema nodosum (new Item 8)

Yes/no

1/0

Pyoderma gangrenosum (new Item 9)

Yes/no

1/0

  1. SCCAI Simple Clinical Colitis Activity Index
  2. aThe SCCAI Score for each item is derived from Table 1