Prediction Ability of Charlson, Elixhauser, and Rx-Risk Comorbidity Indices for Mortality in Patients with Hip Fracture. A Danish Population-Based Cohort Study from 2014 – 2018

Figures & data

Table 1 Characteristics of 31,443 Patients Undergoing Hip Fracture Surgery from 2014 to 2018

	N (%)
All	31,443 (100)
Age in years
65–75	6715 (21.4)
75–85	11,426 (36.3)
85 +	13,302 (42.3)
Gender
Male	9630 (30.6)
Female	21,813 (69.4)
Body mass index
10–19.9	4083 (13.0)
20–24.9	12,450 (39.6)
25–29.9	6866 (21.8)
30 +	2133 (6.8)
Missing	5911 (18.8)
Residence
Own home	21,864 (69.5)
Institution	6796 (21.6)
Unknown	2783 (8.9)
Charlson Comorbidity Index
0	11,862 (37.7)
1	7301 (23.2)
2	5653 (18.0)
3 +	6627 (21.1)
Elixhauser Comorbidity Index
≤ 0	13,951 (44.4)
1–5	7761 (24.7)
6–13	6800 (21.6)
14 +	2931 (9.3)
Rx-Index
−5 – 0	8833 (28.1)
1–3	9753 (31.0)
4–6	6775 (21.5)
7 +	6082 (19.3)

Table 2 C- Statistic and C-Statistic Contrast for Comorbidity Indicies Predicting 30-Day and 1-Year Mortality Among 31,443 Hip Fracture Patients

Model	30 Days Mortality		1 Year Mortality
	C- statistics (95% CI)^a	C- statistic contrast (95% CI)^b	C- statistic (95% CI)^a	C- statistic contrast (95% CI)^b
Age and gender (Base model)	0.699 (0.690–0.709)	Ref.	0.680 (0.673–0.687)	Ref.
Base model + CCI* (continuous)	0.722 (0.713–0.731)	0.022 (0.018–0.027)	0.715 (0.709–0.721)	0.035 (0.031–0.039)
Base model + CCI (in categories)	0.720 (0.711–0.729)	0.021 (0.016–0.025)	0.711 (0.705–0.718)	0.031 (0.027–0.035)
Base model + Elixhauser comorbidity index (continuous)	0.719 (0.710–0.728)	0.019 (0.015–0.024)	0.710 (0.704–0.717)	0.030 (0.026–0.034)
Base model + Elixhauser comorbidity index (in categories)	0.718 (0.709–0.727)	0.019 (0.014–0.023)	0.710 (0.704–0.716)	0.030 (0.026–0.034)
Base model + Rx-risk index (continuous)	0.728 (0.719–0.737)	0.028 (0.023–0.033)	0.716 (0.710–0.723)	0.036 (0.032–0.040)
Base model + Rx-risk index (in categories)	0.726 (0.717–0.735)	0.026 (0.021–0.031)	0.714 (0.708–0.721)	0.034 (0.030–0.038)
Base model + CCI and Elixhauser comorbidity index	0.725 (0.716–0.733)	0.025 (0.020–0.030)	0.719 (0.713–0.726)	0.039 (0.035–0.044)
Base model + CCI and Rx-risk index	0.738 (0.730–0.747)	0.039 (0.033–0.045)	0.734 (0.728–0.740)	0.054 (0.049–0.059)
Base model + Elixhauser and Rx-risk index comorbidity index	0.737 (0.728–0.746)	0.038 (0.032–0.043)	0.731 (0.725–0.737)	0.051 (0.047–0.056)

Notes: *Charlson Comorbidity index. ^aCalculated using the logistic regression model. ^bCalculated as the contrast from the base model (reference group).

Figure 1 Receiver operating characteristic (ROC) curves for 30-day mortality.

Figure 2 Receiver operating characteristic (ROC) curves for 1-year mortality.

Table 3 Odds Ratio (OR) for 30-Day Mortality Among 31,443 Hip Fracture Patients. Comparing Patients with and without Specific Components of Charlson Comorbidity Index, Elixhauser Comorbidity Index and Rx-Risk Index. Adjusted for Age, Gender, and the Remaining Index Components of the Index of Interest

Component		Charlson Comorbidity Index	Elixhauser Comorbidity Index	Rx-Risk Index
Addiction	Alcohol dependency/abuse		1.31 (1.06, 1.63)	0.43 (0.16, 1.18)
	Drug abuse		0.81 (0.36, 1.80)
	Smoking cessation			1.70 (1.14, 2.53)
Cancer	Leukemia	2.02 (1.36, 3.01)
	Lymphoma	1.28 (0.91, 1.79)	1.24 (0.89, 1.73)
	Malignancies			0.45 (0.10, 1.96)
	Metastatic solid tumor	2.46 (1.90, 3.20)	2.35 (1.80, 3.06)
	Tumor (without metastasis)	1.10 (1.00, 1.22)	1.13 (1.01, 1.26)
	Weight loss		1.59 (1.31, 1.93)
Cardiovascular	Anemia, blood loss		1.25 (0.87, 1.79)
	Anemia, deficiency		1.26 (1.05, 1.51)
	Anticoagulants			1.03 (0.92, 1.15)
	Antiplatelets			1.22 (1.12, 1.33)
	Arrhythmia		1.10 (1.00, 1.20)	1.25 (1.08, 1.45)
	Cerebrovascular disease	1.09 (0.99, 1.20)
	Coagulopathy		0.95 (0.65, 1.38)
	Congestive heart failure	1.49 (1.32, 1.67)	1.37 (1.22, 1.55)	1.57 (1.41, 1.75)
	Fluid and electrolyte disorders		1.32 (1.20, 1.46)
	Hyperlipidemia			0.78 (0.71, 0.86)
	Hypertension		0.92 (0.84, 1.00)	1.24 (1.14, 1.34)
	Ischemic heart disease angina			1.26 (1.10, 1.44)
	Ischemic heart disease hypertension			0.97 (0.90, 1.05)
	Myocardial infarction	1.14 (0.97, 1.33)
	Peripheral vascular disease	1.30 (1.15, 1.47)	1.28 (1.13, 1.45)
	Valvular disease		1.31 (1.15, 1.49)
Endocrinology	Diabetes, uncomplicated	1.14 (1.00, 1.30)	1.10 (0.95, 1.27)	1.21 (1.07, 1.37)
	Diabetes, complicated	1.02 (0.74, 1.41)	1.13 (0.93, 1.36)
	Hyperthyroidism			1.38 (0.70, 2.72)
	Hypothyroidism		0.91 (0.73, 1.13)	0.86 (0.74, 1.00)
	Obesity		1.00 (0.76, 1.31)
	Osteoporosis/Paget’s			0.85 (0.75, 0.97)
	Steroid-responsive disease			1.41 (1.24, 1.59)
Gastrointestinal	Gastroesophageal reflux disease/peptic ulcer	0.98 (0.83, 1.16)	0.95 (0.73, 1.25)	1.15 (1.05, 1.25)
	Irritable bowel syndrome			1.08 (0.77, 1.53)
	Mild liver disease	1.65 (1.15, 2.37)	1.43 (1.07, 1.91)
	Moderate to severe liver disease/Liver failure	1.89 (1.14, 3.14)		1.53 (1.30, 1.81)
	Pancreatic insufficiency			2.84 (1.78, 4.54)
Infection	HIV/AIDS	3.59 (0.95, 13.61)	1.89 (0.22, 16.13)
Respiratory	Chronic airways disease	1.68 (1.51, 1.86)	1.60 (1.44, 1.77)	1.41 (1.27, 1.56)
	Pulmonary circulation disorders		0.95 (0.76, 1.18)
Neurology	Dementia	2.15 (1.94, 2.37)		1.71 (1.52, 1.93)
	Epilepsy			1.03 (0.89, 1.19)
	Migraine			0.45 (0.14, 1.44)
	Other neurological disorders		1.20 (1.02, 1.40)
	Paralysis or Hemiplegia/paraplegia	0.65 (0.20, 2.10)	0.80 (0.34, 1.86)
	Parkinson´s disease			1.00 (0.83, 1.20)
Psychiatry	Anxiety			0.99 (0.87, 1.13)
	Bipolar disorder			1.14 (0.61, 2.12)
	Depression		0.99 (0.84, 1.16)	1.17 (1.08, 1.28)
	Psychotic illness/psychosis		1.93 (1.20, 3.12)	1.99 (1.76, 2.26)
Rheumatology	Allergies			1.01 (0.88, 1.16)
	Gout			1.23 (1.03, 1.47)
	Inflammation/pain			0.91 (0.81, 1.02)
	Pain			1.03 (0.95, 1.12)
	Rheumatic disease	0.88 (0.73, 1.07)	0.88 (0.72, 1.06)
Urology	Benign prostatic hyperplasia			0.86 (0.73, 1.00)
	Incontinence			0.68 (0.56, 0.83)
	Renal disease/failure	1.67 (1.46, 1.92)	1.63 (1.41, 1.90)	1.09 (0.58, 2.04)

Table 4 Odds Ratio (OR) for 1-Year Mortality Among 31,443 Hip Fracture Patients. Comparing Patients with and without Specific Components of Charlson Comorbidity Index, Elixhauser Comorbidity Index and Rx-Risk Index. Adjusted for Age, Gender, and the Remaining Index Components of the Index of Interest

Component		Charlson Comorbidity Index	Elixhauser Comorbidity Index	Rx-Risk Index
Addiction	Alcohol dependency/abuse		1.60 (1.38, 1.84)	0.83 (0.53, 1.30)
	Drug abuse		1.05 (0.65, 1.71)
	Smoking cessation			1.71 (1.28, 2.30)
Cancer	Leukemia	2.09 (1.54, 2.84)
	Lymphoma	1.58 (1.25, 1.99)	1.53 (1.21, 1.93)
	Malignancies			1.46 (0.66, 3.21)
	Metastatic solid tumor	4.33 (3.57, 5.25)	4.02 (3.30, 4.89)
	Tumor (without metastasis)	1.36 (1.27, 1.46)	1.44 (1.33, 1.56)
	Weight loss		1.60 (1.37, 1.85)
Cardiovascular	Anemia, blood loss		1.16 (0.88, 1.54)
	Anemia, deficiency		1.20 (1.04, 1.38)
	Anticoagulants			1.07 (0.98, 1.16)
	Antiplatelets			1.24 (1.16, 1.31)
	Arrhythmia		1.14 (1.07, 1.22)	1.44 (1.29, 1.60)
	Cerebrovascular disease	1.19 (1.11, 1.28)
	Coagulopathy		1.05 (0.80, 1.37)
	Congestive heart failure	1.53 (1.40, 1.68)	1.38 (1.26, 1.52)	1.50 (1.39, 1.63)
	Fluid and electrolyte disorders		1.49 (1.39, 1.60)
	Hyperlipidemia			0.77 (0.73, 0.83)
	Hypertension		0.96 (0.90, 1.02)	1.11 (1.05, 1.18)
	Ischemic heart disease angina			1.06 (0.96, 1.18)
	Ischemic heart disease hypertension			0.94 (0.89, 1.00)
	Myocardial infarction	1.07 (0.95, 1.20)
	Peripheral vascular disease	1.29 (1.18, 1.41)	1.26 (1.15, 1.38)
	Valvular disease		1.27 (1.15, 1.40)
Endocrinology	Diabetes, uncomplicated	1.17 (1.07, 1.29)	1.13 (1.01, 1.25)	1.22 (1.12, 1.34)
	Diabetes, complicated	1.03 (0.82, 1.29)	1.13 (0.99, 1.30)
	Hyperthyroidism			1.15 (0.68, 1.94)
	Hypothyroidism		0.89 (0.76, 1.03)	0.99 (0.90, 1.10)
	Obesity		0.93 (0.77, 1.12)
	Osteoporosis/Paget’s			0.84 (0.77, 0.91)
	Steroid-responsive disease
Gastrointestinal	Gastroesophageal reflux disease/peptic ulcer	1.23 (1.09, 1.38)	1.01 (0.83, 1.23)	1.20 (1.13, 1.27)
	Irritable bowel syndrome			1.09 (0.86, 1.38)
	Mild liver disease	1.60 (1.24, 2.06)	1.27 (1.03, 1.56)
	Moderate to severe liver disease/Liver failure	1.71 (1.17, 2.49)		1.65 (1.45, 1.88)
	Pancreatic insufficiency			2.84 (1.99, 4.07)
Infection	HIV/AIDS	1.51 (0.45, 5.07)	1.35 (0.25, 7.23)
Respiratory	Chronic airways disease	1.60 (1.48, 1.73)	1.50 (1.39, 1.62)	1.31 (1.22, 1.41)
	Pulmonary circulation disorders		1.08 (0.92, 1.26)
Neurology	Dementia	2.39 (2.21, 2.58)		1.82 (1.66, 1.99)
	Epilepsy			0.95 (0.86, 1.05)
	Migraine			0.47 (0.24, 0.90)
	Other neurological disorders		1.28 (1.15, 1.43)
	Paralysis or Hemiplegia/paraplegia	0.72 (0.37, 1.39)	0.87 (0.52, 1.45)
	Parkinson´s disease			1.03 (0.91, 1.16)
Psychiatry	Anxiety			1.12 (1.02, 1.22)
	Bipolar disorder			0.87 (0.55, 1.37)
	Depression		1.05 (0.94, 1.17)	1.25 (1.18, 1.33)
	Psychotic illness/psychosis		1.73 (1.22, 2.45)	1.87 (1.70, 2.06)
Rheumatology	Allergies			0.91 (0.83, 1.00)
	Gout			1.18 (1.03, 1.35)
	Inflammation/pain			0.88 (0.81, 0.95)
	Pain			1.24 (1.17, 1.32)
	Rheumatic disease	0.97 (0.85, 1.09)	0.94 (0.83, 1.07
Urology	Benign prostatic hyperplasia			0.93 (0.82, 1.04)
	Incontinence			0.69 (0.60, 0.78)
	Renal disease/failure	1.60 (1.44, 1.79)	1.60 (1.42, 1.81)	1.62 (1.02, 2.56)