Table 3.
Inverse probability weighting (IPW)-adjusted logistic regression analysis to assess the associations of intraepithelial T-cell densities (predictor) with tumour budding at invasive front (outcome) .
| Univariable OR (95% CI)b,c | Multivariable OR (95% CI)b,c | |
|---|---|---|
| Intraepithelial CD3+ cell density (cells/mm2) | ||
| C1 (lowest) | 1 (referent) | 1 (referent) |
| C2 (second) | 0.75 (0.52–1.09) | 0.74 (0.51–1.08) |
| C3 (third) | 0.62 (0.43–0.89) | 0.61 (0.43–0.88) |
| C4 (highest) | 0.64 (0.44–0.93) | 0.60 (0.41–0.88) |
| Ptrendd | 0.010 | 0.005 |
| Intraepithelial CD3+CD8+ cell density (cells/mm2)a | ||
| C1 (zero) | 1 (referent) | 1 (referent) |
| C2 (low) | 0.92 (0.64–1.32) | 0.92 (0.64–1.32) |
| C3 (intermediate) | 0.57 (0.40–0.82) | 0.57 (0.40–0.81) |
| C4 (high) | 0.52 (0.37–0.73) | 0.50 (0.35–0.70) |
| Ptrendd | < 0.001 | < 0.001 |
| Intraepithelial CD3+CD8+CD45RO+ cell density (cells/mm2)a | ||
| C1 (zero) | 1 (referent) | 1 (referent) |
| C2 (low) | 0.73 (0.51–1.06) | 0.73 (0.50–1.05) |
| C3 (intermediate) | 0.58 (0.41–0.82) | 0.57 (0.40–0.81) |
| C4 (high) | 0.47 (0.33–0.67) | 0.44 (0.31–0.63) |
| Ptrendd | < 0.001 | < 0.001 |
As intraepithelial CD3+CD8+ (377 cases) and CD3+CD8+CD45RO+ (424 cases) cell densities were 0/mm2 (consisting the largest category C1), the remaining cases were divided into tertiles according to density (C2-C4).
IPW was applied to reduce a bias due to the availability of tumour tissue after cancer diagnosis (see “Statistical analysis” subsection for details).
The multivariable ordinal logistic regression model initially included age, sex, year of diagnosis, family history of colorectal cancer, tumour location, microsatellite instability, CpG island methylator phenotype, long-interspersed nucleotide element-1 methylation level, KRAS, BRAF, and PIK3CA mutations, CDH1 expression, and CTNNB1 expression. A backward elimination with a threshold P of 0.05 was used to select variables for the final model.
Ptrend was calculated by the linear trend across the ordinal categories of the intraepithelial T-cell densities (four ordinal predictor variables: C1-C4) in the IPW-adjusted ordinal logistic regression model for the number of tumour buds/0.785 mm2 at invasive front (tertile variables).