Two level hierarchical logistic regression model for upper gastrointestinal surgery in all 29 hospitals

Risk factor
Coefficient $beta$
Standard error
Odds ratio (95% CI)*

Age (per 10 year increase) 0.48 0.11 1.62 (1.28 to 1.99)

POSSUM score 0.77 0.17 2.16 (1.54 to 3.03)

POSSUM malignancy category:

  Primary only 0.27 0.37 1.35 (0.60 to 2.56)

  Nodal disease 0.53 0.42 1.78 (0.70 to 3.64)

  Metastatic disease 1.04 0.50 3.14 (1.06 to 7.16)

Mode of surgery:

  Emergency 0.57 0.37 1.78 (0.88 to 3.82)

Constant $-$ 7.24 0.96 $---$

Level 2 variance 0.26 0.16 $---$

^* Bias corrected bootstrap confidence intervals (10 000 iterations).

Odds ratios and 95% confidence intervals are shown for every 10 year increase in age or 10 unit increase in POSSUM score.

Reference categories: no malignancy for POSSUM malignancy category; elective surgery for mode of surgery.