Table 2. Effect of incident acute cholecystitis on 30-day mortality.

Variables		aRR	95% CI	P value
Acute cholecystitis
	No	1
	Yes	4.35	1.66–11.34	0.011
Age group
	65–69	1
	70–74	1.64	0.77–3.49	0.196
	75–79	2.03	0.98–4.20	0.058
	80–84	2.73	1.33–5.61	0.006
	≥ 85	5.84	2.87–11.87	< 0.001
Gender
	Men	1.91	1.59–2.31	< 0.001
	Women	1
Income
	Low	1.04	0.79–1.36	0.785
	Mid-low	0.80	0.80–0.61	0.113
	Mid-high	0.98	0.78–1.23	0.872
	High	1
Residential area
	Metropolitan	1
	Non-metropolitan	1.06	0.88–1.28	0.553
CCS
	0	1
	1–2	1.21	0.95–1.54	0.121
	3–6	1.22	0.93–1.59	0.154
	≥ 6	1.25	0.89–2.05	0.161
Fracture type
	Neck fracture	1
	Pertrochanteric fracture	0.97	0.78–1.20	0.762
Surgery type
	Hemiarthroplasty	1
	Internal fixation	0.97	0.76–1.24	0.824
	Traction	2.46	1.86–3.26	< 0.001
Anesthesia
	General	1
	Spinal	0.90	0.70–1.17	0.372
	Unknown	1.63	1.21–2.18	0.011
Hospital beds
	< 200	1.06	0.80–1.39	0.694
	200–499	0.95	0.74–1.21	0.681
	500–799	0.93	0.70–1.23	0.594
	≥ 800	1

aRR = adjusted risk ratio, CI = confidence interval, CCS = Charlson Comorbidity Score.