Table 2. Multivariable logistic regression of surgical treatment vs. non-surgical treatment, conditional on individual patient characteristics.

Variable	Odds ratio of having surgery	95% CI	P
Age at diagnosis
70 years	Reference	–	–
Per year over 70	0.84	0.82-0.87	<0.001*
Tumour grade
1	Reference	–	–
2	0.92	0.58-1.46	0.723
3	1.18	0.63-2.21	0.600
HER2 status
Negative	Reference	–	–
Positive/borderline	1.71	0.95-3.07	0.075
Nodal status
Negative	Reference
Positive	0.85	0.54-1.34	0.495
Tumour size
<10 mm	Reference	–	–
10-19.9 mm	0.81	0.41-1.61	0.551
20-49.9 mm	0.84	0.56-1.25	0.396
≥50 mm	0.36	0.19-0.70	0.003*
Mini-Mental State Examination (MMSE) score
27-30	Reference	–	–
22-26	0.89	0.54-1.48	0.658
0-21	0.57	0.26-1.24	0.156
Activities of daily living (ADL) score
Independent	Reference	–	–
Dependent	0.44	0.28-0.69	<0.001*
Charlson Comorbidity Index (CCI) score
0	Reference	–	–
1	0.58	0.36-0.95	0.023*
2	0.58	0.37-0.94	0.026*
≥3	0.47	0.28-0.69	<0.001*

Odds ratio >1 indicates increased odds of receiving surgery. * indicates statistical significance at 5% level.