Table 1.
Definitions of Variables Used in the Data Analysis.
| Variable | Type | Description |
|---|---|---|
| Age | Continuous | At each time point |
| Sex | Categorical | Male, female |
| Disease duration | Continuous | Duration of CD from the day of diagnosis |
| Times | Categorical | Time 1 = Baseline, Time 2 = Midpoint Time 3 = Endpoint |
| Months | Continuous | Number of months from the first visit |
| HBI score | Continuous/Categorical | 1. Remission < 5 2. Active disease ≥ 5 |
| History of surgery | Categorical | Yes, No |
| hs-CRP level | Continuous/Categorical | 3. Low-risk < 1 4. Intermediate risk between 1–3 5. High risk > 3 |
| 25(OH)D level | Categorical | 1. Vit D deficient < 30 nmol/L 2. Vit D insufficient 30–50 nmol/L 3. Vit D adequate 51–74 nmol/L 4. Vit D optimal > 75 nmol/L |
| Vitamin D supplementation | Continuous | Amount of vitamin D (IU/day) |
| Season | Categorical | 1. April to September (“summer”) 2. October to March (“winter”) |
| Corticosteroid drugs use | Categorical | Yes, No |
HBI: Harvey-Bradshaw index; Hs-CRP: High-sensitivity C-reactive protein; 25(OH)D: 25hydroxyvitamin D.