Factors associated with emergency department presentation after total joint arthroplasty: a population-based retrospective cohort study

Bheeshma Ravi; Timothy Leroux; Peter C. Austin; J. Michael Paterson; Suriya Aktar; Donald A. Redelmeier

doi:10.9778/cmajo.20190116

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Table 1:

Characteristics of eligible total hip arthroplasty recipients

Characteristic	No. (%) of patients^*			Standardized difference
Characteristic	All patients n = 42 273	Emergency department visit n = 5640	No emergency department visit n = 36 633	Standardized difference
Age, yr, median (IQR)	67 (59–74)	68 (60–76)	67 (59–74)	0.12
Sex
Female	22 758 (53.8)	2881 (51.1)	19 877 (54.3)	0.06
Male	19 515 (46.2)	2759 (48.9)	16 756 (45.7)	0.06
Rural residence	6956 (16.5)	1218 (21.6)	5738 (15.7)	0.15
Ethnic concentration quintile^†^‡
1 (lowest)	10 601 (25.2)	1595 (28.5)	9006 (24.7)	0.09
2	9968 (23.7)	1324 (23.7)	8644 (23.7)	0.0
3	8988 (21.4)	1087 (19.4)	7901 (21.7)	0.06
4	7524 (17.9)	945 (16.9)	6579 (18.1)	0.03
5 (highest)	4961 (11.8)	643 (11.5)	4318 (11.8)	0.01
Instability quintile^†^‡
1 (lowest)	6457 (15.4)	731 (13.1)	5726 (15.7)	0.08
2	8589 (20.4)	1063 (19.0)	7526 (20.6)	0.04
3	9031 (21.5)	1223 (21.9)	7808 (21.4)	0.01
4	8673 (20.6)	1265 (22.6)	7408 (20.3)	0.06
5 (highest)	9292 (22.1)	1312 (23.5)	7980 (21.9)	0.04
Dependency quintile^†^‡
1 (lowest)	5771 (13.7)	744 (13.3)	5027 (13.8)	0.01
2	7018 (16.7)	890 (15.9)	6128 (16.8)	0.02
3	7945 (18.9)	977 (17.5)	6968 (19.1)	0.04
4	8714 (20.7)	1150 (20.6)	7564 (20.8)	0.0
5 (highest)	12 594 (30.0)	1833 (32.8)	10 761 (29.5)	0.07
Deprivation quintile^†^‡
1 (lowest)	10 144 (24.1)	1219 (21.8)	8925 (24.5)	0.06
2	9217 (21.9)	1203 (21.5)	8014 (22.0)	0.01
3	8375 (19.9)	1151 (20.6)	7224 (19.8)	0.02
4	7845 (18.7)	1091 (19.5)	6754 (18.5)	0.02
5 (highest)	6461 (15.4)	930 (16.6)	5531 (15.2)	0.04
Income quintile^‡
1 (lowest)	6475 (15.3)	964 (17.1)	5511 (15.1)	0.06
2	7861 (18.6)	1072 (19.1)	6789 (18.6)	0.01
3	8446 (20.0)	1135 (20.2)	7311 (20.0)	0.0
4	8899 (21.1)	1173 (20.8)	7726 (21.1)	0.01
5 (highest)	10 510 (24.9)	1282 (22.8)	9228 (25.2)	0.06
Comorbidities
Asthma	1483 (3.5)	252 (4.5)	1231 (3.4)	0.06
Coronary artery disease	1358 (3.2)	220 (3.9)	1138 (3.1)	0.05
Congestive heart failure	1773 (4.2)	305 (5.4)	1468 (4.0)	0.07
Chronic obstructive pulmonary disease	7304 (17.3)	1186 (21.0)	6118 (16.7)	0.11
Counselled about smoking cessation	2560 (6.1)	351 (6.2)	2209 (6.0)	0.01
Diabetes	8396 (19.9)	1219 (21.6)	7177 (19.6)	0.05
Complicated diabetes	1553 (3.7)	261 (4.6)	1292 (3.5)	0.06
Hypertension	26 723 (63.2)	3768 (66.8)	22 955 (62.7)	0.09
Frailty	2077 (4.9)	309 (5.5)	1768 (4.8)	0.03
Body mass index > 40	2462 (5.8)	391 (6.9)	2071 (5.7)	0.05
Charlson Comorbidity Index score
0	32 511 (76.9)	4196 (74.4)	28 315 (77.3)	0.07
1	6141 (14.5)	832 (14.8)	5309 (14.5)	0.01
2	2344 (5.5)	403 (7.1)	1941 (5.3)	0.08
≥ 3	1277 (3.0)	209 (3.7)	1068 (2.9)	0.04
Admission characteristics
Hospital volume, median (IQR)	277 (195–515)	274 (193–510)	278 (195–516)	0.02
Surgeon volume, median (IQR)	69 (47–105)	70 (46–104)	69 (47–105)	0.01
General anesthesia	7649 (18.1)	1024 (18.2)	6625 (18.1)	0.00
Change in annual health care costs, 2013 dollars, median (IQR)	−733 (−2228 to 2866)	501 (−1587 to 8417)	−865 (−2292 to 2071)	0.35
Readmission within 30 d	130 (0.3)	58 (1.0)	72 (0.2)	0.11

Note: IQR = interquartile range.
↵* Except where noted otherwise.
↵† Ontario Marginalization Index.
↵‡ Data not available for all patients.

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Table 2:

Characteristics of eligible total knee arthroplasty recipients

Characteristic	No. (%) of patients^*			Standardized difference
Characteristic	All patients n = 70 725	Emergency department visit n = 11 224	No emergency department visit n = 59 501	Standardized difference
Age, yr, median (IQR)	67 (61–74)	68 (61–75)	67 (61–74)	0.09
Sex
Female	43 915 (62.1)	6543 (58.3)	37 372 (62.8)	0.09
Male	26 810 (37.9)	4681 (41.7)	22 129 (37.2)	0.09
Rural residence	11 505 (16.3)	2563 (22.8)	8942 (15.0)	0.20
Ethnic concentration quintile^†^‡
1 (lowest)	17 345 (24.7)	3331 (30.0)	14 014 (23.7)	0.14
2	15 976 (22.7)	2561 (23.1)	13 415 (22.7)	0.01
3	13 634 (19.4)	2036 (18.3)	11 598 (19.6)	0.03
4	11 789 (16.8)	1616 (14.5)	10 173 (17.2)	0.07
5 (highest)	11 559 (16.4)	1564 (14.1)	9995 (16.9)	0.08
Instability quintile^†^‡
1 (lowest)	12 143 (17.3)	1700 (15.3)	10 443 (17.6)	0.06
2	14 062 (20.0)	2149 (19.3)	11 913 (20.1)	0.02
3	14 783 (21.0)	2372 (21.4)	12 411 (21.0)	0.01
4	14 605 (20.8)	2526 (22.7)	12 079 (20.4)	0.06
5 (highest)	14 710 (20.9)	2361 (21.3)	12 349 (20.9)	0.01
Dependency quintile^†^‡
Lowest	10 123 (14.4)	1407 (12.7)	8716 (14.7)	0.06
2	11 831 (16.8)	1702 (15.3)	10 129 (17.1)	0.05
3	13 216 (18.8)	1975 (17.8)	11 241 (19.0)	0.03
4	14 776 (21.0)	2466 (22.2)	12 310 (20.8)	0.03
5 (highest)	20 357 (29.0)	3558 (32.0)	16 799 (28.4)	0.08
Deprivation quintile^†^‡
1 (lowest)	14 270 (20.3)	2118 (19.1)	12 152 (20.5)	0.04
2	14 722 (20.9)	2187 (19.7)	12 535 (21.2)	0.04
3	14 300 (20.3)	2339 (21.1)	11 961 (20.2)	0.02
4	14 267 (20.3)	2328 (21.0)	11 939 (20.2)	0.02
5 (highest)	12 744 (18.1)	2136 (19.2)	10 608 (17.9)	0.03
Income quintile^‡
1 (lowest)	12 129 (17.2)	2152 (19.2)	9977 (16.8)	0.06
2	14 566 (20.6)	2359 (21.1)	12 207 (20.6)	0.01
3	14 652 (20.8)	2221 (19.8)	12 431 (20.9)	0.03
4	14 458 (20.5)	2235 (20.0)	12 223 (20.6)	0.02
5 (highest)	14 773 (20.9)	2235 (20.0)	12 538 (21.1)	0.03
Comorbidities
Asthma	3268 (4.6)	630 (5.6)	2638 (4.4)	0.05
Coronary artery disease	2186 (3.1)	425 (3.8)	1761 (3.0)	0.05
Congestive heart failure	3271 (4.6)	701 (6.2)	2570 (4.3)	0.09
Chronic obstructive pulmonary disease	13 148 (18.6)	2521 (22.5)	10 627 (17.9)	0.11
Counselled about smoking cessation	3352 (4.7)	595 (5.3)	2757 (4.6)	0.03
Diabetes	20 508 (29.0)	3409 (30.4)	17 099 (28.7)	0.04
Complicated diabetes	3650 (5.2)	743 (6.6)	2907 (4.9)	0.07
Hypertension	51 267 (72.5)	8358 (74.5)	42 909 (72.1)	0.05
Frailty	3407 (4.8)	635 (5.7)	2772 (4.7)	0.05
Charlson Comorbidity Index score
0	50 204 (71.0)	7596 (67.7)	42 608 (71.6)	0.09
1	13 274 (18.8)	2252 (20.1)	11 022 (18.5)	0.04
2	4799 (6.8)	863 (7.7)	3936 (6.6)	0.04
≥ 3	2448 (3.5)	513 (4.6)	1935 (3.2)	0.07
Admission characteristics
Hospital volume, median (IQR)	429 (315–607)	427 (311–597)	429 (315–609)	0.04
Surgeon volume, median (IQR)	104 (72–138)	104 (71–137)	104 (72–138)	0.01
General anesthesia	11 470 (16.2)	1859 (16.6)	9611 (16.2)	0.01
Change in annual health care costs, 2013 dollars, median (IQR)	−586 (−2356 to 5248)	682 (−1673 to 8227)	−771 (−2449 to 4330)	0.30
Readmission within 30 d	156 (0.2)	70 (0.6)	86 (0.1)	0.08

Note: IQR = interquartile range.
↵* Except where noted otherwise.
↵† Ontario Marginalization Index.
↵‡ Data not available for all patients.

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Table 3:

Reasons for emergency department visit within 30 days of surgery

Diagnosis	No. (%) of patients
Diagnosis	Total hip arthroplasty n = 5640	Total knee arthroplasty n = 11 224
Wound issue	1614 (28.6)	2617 (23.3)
Concern about infection	776 (13.8)	2316 (20.6)
Acute pain	906 (16.1)	1777 (15.8)
Cardiovascular diagnosis	501 (8.9)	1118 (10.0)
Gastrointestinal diagnosis	487 (8.6)	1131 (10.1)
Possible thrombophlebitis	402 (7.1)	623 (5.6)
Family-practice–sensitive condition	308 (5.5)	578 (5.1)
Genitourinary disorder	277 (4.9)	418 (3.7)
Preexisting medical issue	191 (3.4)	197 (1.8)
Reaction to medications	62 (1.1)	134 (1.2)
Miscellaneous	116 (2.0)	315 (2.8)

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Table 4:

Multivariable models predicting all-cause emergency department visit within 30 days of surgery

Variable	Adjusted OR (95% CI)
Total hip arthroplasty recipients
Age, yr
< 50 v. 50–70	1.11 (0.99–1.25)
> 70 v. 50–70	1.33 (1.25–1.41)
Male sex	1.17 (1.11–1.24)
Chronic obstructive pulmonary disease	1.28 (1.20–1.38)
Obesity	1.30 (1.16–1.46)
Hypertension	1.12 (1.05–1.19)
Rural residence	1.48 (1.38–1.59)
C-statistic: 0.571
Total knee arthroplasty recipients
Age, yr
< 50 v. 50–70	1.28 (1.15–1.44)
> 70 v. 50–70	1.24 (1.19–1.29)
Male sex	1.18 (1.13–1.23)
Chronic obstructive pulmonary disease	1.26 (1.19–1.32)
Congestive heart failure	1.28 (1.17–1.39)
Asthma	1.25 (1.14–1.37)
Diabetes (complicated)	1.21 (1.11–1.32)
Low income	1.13 (1.07–1.19)
Rural residence	1.64 (1.56–1.72)
C-statistic: 0.578