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)dagger 0.48 0.11 1.62 (1.28 to 1.99)
POSSUM scoredagger 0.77 0.17 2.16 (1.54 to 3.03)
POSSUM malignancy categoryDagger:
  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 surgeryDagger:
  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).
dagger Odds ratios and 95% confidence intervals are shown for every 10 year increase in age or 10 unit increase in POSSUM score.
Dagger Reference categories: no malignancy for POSSUM malignancy category; elective surgery for mode of surgery.