Does BMI influence hospital stay and morbidity after fast-track hip and knee arthroplasty?

Figures & data

Table 1. Distribution of grouped BMI on type of procedure

Joint of surgery/BMI	Number of patients	Fraction
Hip, median: 26.6, IQR: 24.0–29.7
<18.5	77	1.1
18.5–24.9	2,396	33.3
25.0–29.9	3,008	41.8
30.0–34.9	1,329	18.5
35.0–39.9	299	4.2
>39.9	85	1.2
Total	7194	100
Knee, median: 28.9, IQR: 25.8–32.6
<18.5	29	0.4
18.5–24.9	1,250	19.1
25.0–29.9	2,524	38.6
30.0–34.9	1,745	26.7
35.0–39.9	699	10.7
>39.9	289	4.4
Total	6,536	100

IQR: Interquartile range

Table 3. Fractions of patients with a LOS >4 days, 90 days readmissions and specific conditions according to BMI group. Values are n (%; 95% confidence intervals)

Joint BMI	LOS >4 days	p-value	90–days readmissions	p–value	Specific complications	p-value
THA
< 18.5	10 (13.0; 7.2–22.3)	0.1	3 (3.4; 1.3–11)	0.2	2 (2.6; 0.7–9.0)	0.6
18.5–24.9	189 (7.9; 6.9–9.0)	–	209 (8.7; 7.7–9.9)	–	113 (4.7; 3.9–5.6)	–
25.0–29.9	188 (6.3; 5.4–7.2)	0.02	237 (7.9; 7.0–8.9)	0.3	135 (4.5; 3.8–5.3)	0.7
30.0–34.9	98 (7.4; 6.1–8.9)	0.6	125 (9.4; 8.0–11)	0.5	83 (6.3; 5.1–7.7)	0.05
35.0–39.9	35 (11.7; 8.5–15.9)	0.02	35 (11.7; 8.5–16)	0.09	21 (7.0; 4.6–10.5)	0.08
≥ 40.0	11 (12.9; 7.4–21.7)	0.09	9 (10.6; 5.7–19)	0.6	7 (8.2; 4.1–16.0)	0.2
TKA
< 18.5	5 (17.2; 7.6–34.6)	0.3	4 (5.2; 2.0–13)	0.5	0 (0.0; 0.0–4.8)	1
18.5–24.9	141 (11.3; 9.6–13.2)	–	120 (9.6; 8.1–11)	–	33 (2.6; 1.9–3.7)	–
25.0–29.9	213 (8.4; 7.4–9.6)	0.005	200 (7.9; 6.9–9.0)	0.08	47 (1.9; 1.4–2.5)	0.2
30.0–34.9	145 (8.3; 7.1–9.7)	0.006	133 (7.6; 6.5–9.0)	0.06	29 (1.7; 1.2–2.4)	0.06
35.0–39.9	70 (10.0; 8.0–12.5)	0.4	66 (9.4; 7.5–12)	0.9	16 (2.3; 1.4–3.7)	0.6
≥ 40.0	35 (11.7; 8.6–15.9)	0.7	22 (7.4; 4.9–11)	0.3	11 (3.7; 2.1–6.5)	0.3

BMI: body mass index THA: total hip arthroplasty TKA: total knee arthroplasty. Comparisons are vs. BMI of 18.5–24.9

Table 4. Multiple logistic regression THA (n = 6,809)

	LOS >4 days (n = 502)			90-days readmission (n = 584)			Specific complications (n = 336)
Variable	OR	95%CI	p-value	OR	95%CI	p-value	OR	95%CI	p-value
BMI			< 0.001			0.1			0.01
< 18.5	1.19	0.55–2.59	0.7	0.4	0.11–1.20	0.1	0.47	0.11–2.00	0.3
18.5–24.9	1	–	–	1	–	–	1	–	–
25.0–29.9	0.96	0.76–1.21	0.7	0.93	0.75–1.14	0.5	1.02	0.78–1.35	0.9
30.0–34.9	1.28	0.97–1.21	0.09	1.17	0.91–1.50	0.2	1.55	1.13–2.11	0.006
35.0–39.9	2.10	1.37–3.23	0.001	1.30	0.85–1.96	0.2	1.83	1.10–3.04	0.02
> 39.9	3.23	1.58–6.59	0.001	1.24	0.57–2.70	0.6	1.65	0.64–4.29	0.3
Age/year	1.05	1.03–1.06	< 0.001	1.03	1.02–1.04	< 0.001	1.03	1.01–1.04	< 0.001
Male vs female	0.90	0.72–1.11	0.3	1.10	0.91–1.33	0.3	0.97	0.77–1.24	0.8
Living			< 0.001			0.8			0.7
With others	1	–	–	1	–	–	1	–	–
Alone	1.78	1.45–2.20	< 0.001	1.05	0.86–1.27	0.6	1.10	0.86–1.34	0.5
Institution	1.86	0.87–4.00	0.1	1.18	0.53–2.62	0.7	1.31	0.50–3.45	0.6
Walking aid	2.31	1.87–2.85	< 0.001	1.59	1.31–1.93	< 0.001	1.26	0.97–1.62	0.08
Pre-op. anemia	1.98	1.58–2.48	< 0.001	1.44	1.15–1.80	0.002	1.48	1.12–1.20	0.007
Diabetes			0.4			0.4			0.3
No DM	1	–	–	1	–	–	1	–	–
IDDM	1.48	0.85–2.58	0.1	1.40	0.83–2.37	0.2	1.15	0.58–2.28	0.7
NIDDM	1.07	0.75–1.53	0.7	0.99	0.72–1.38	1	0.70	0.44–1.12	0.1
Hypertension	0.80	0.65–0.99	0.04	1.13	0.94–1.37	0.2	1.10	0.86–1.39	0.5
Anticoagulants	1.20	0.81–1.78	0.4	1.33	0.93–1.90	0.1	0.57	0.33–0.80	0.04
Cardiac disease	1.53	1.15–2.04	0.003	1.42	1.10–1.85	0.008	1.72	1.25–2.36	0.001
Pulmonary disease	1.40	1.04–1.87	0.03	1.42	1.10–1.85	0.008	1.20	0.83–1.74	0.3
Psychiatric disorder	1.82	1.44–2.31	< 0.001	1.54	1.22–1.93	< 0.001	1.31	0.97–1.77	0.08

THA: total hip arthroplasty, LOS: length of stay, OR: odds ratio, CI: confidence interval, BMI: body mass index DM: diabetes mellitus, IDDM: insulin dependent diabetes mellitus, NIDDM: non-insulin dependent diabetes mellitus.

Table 5. Multiple logistic regression TKA (n = 6,123)

	LOS >4 days (n = 559)			90–days readmission (n = 499)			Specific complications (n = 122)
Variable	OR	95%CI	p-value	OR	95%CI	p-value	OR	95%CI	p-value
BMI			0.2			0.1			1
< 18.5	1.96	0.66–5.85	0.2	1.94	0.64–5.89	0.2	0.67	0.06–6.99	0.7
18.5–24.9	1	–	–	1	–	–	1	–	–
25.0–29.9	0.78	0.60–0.99	0.049	0.84	0.66–1.09	0.2	0.93	0.65–1.32	0.7
30.0–34.9	0.85	0.65–1.12	0.3	0.76	0.57–1.01	0.06	0.91	0.62–1.35	0.6
35.0–39.9	1.08	0.76–1.53	0.7	0.93	0.66–1.33	0.7	1.02	0.62–1.67	0.9
> 39.9	1.04	0.64–1.69	0.9	0.57	0.33–0.99	0.046	1.19	0.62–2.26	0.6
Age/year	1.04	1.02–1.05	< 0.001	1.01	1.00–1.02	0.04	1.01	0.99–1.02	0.2
Male vs female	1.01	0.82–1.24	< 0.001	1.31	1.07–1.59	0.008	1.10	0.84–1.44	0.5
Living			< 0.001			0.8			0.7
With others	1	–	–	1	–	–	1	–	–
Alone	1.60	1.31–2.00	< 0.001	1.05	0.85–1.28	0.7	0.98	0.74–1.30	0.9
Institution	1.21	0.37–3.97	0.7	3.15	1.20–8.25	0.02	0.64	0.07–6.35	0.7
Walking aid	2.43	1.98–2.98	< 0.001	1.66	1.34–2.06	< 0.001	1.27	0.93–1.73	0.1
Pre–op. anemia	1.70	1.34–2.15	< 0.001	1.41	1.10–1.82	0.007	0.96	0.65–1.43	0.8
Diabetes			0.4			0.4			0.3
No DM	1	–	–	1	–	–	1	–	–
IDDM	1.48	0.94–2.33	0.09	1.62	1.04–2.53	0.03	1.24	0.63–2.44	0.5
NIDDM	1.23	0.91–1.65	0.2	1.23	0.92–1.66	0.2	0.98	0.63–1.53	0.9
Hypertension	1.08	0.89–1.32	0.4	1.10	0.90–1.34	0.4	0.92	0.70–1.23	0.6
Anticoagulants	1.60	1.10–2.35	0.02	1.25	0.84–1.86	0.3	0.97	0.52–1.79	0.9
Cardiac disease	1.26	0.95–1.67	0.1	1.23	0.93–1.63	0.2	1.17	0.78–1.77	0.4
Pulmonary disease	1.35	0.99–1.83	0.05	1.18	1.36–2.41	< 0.001	1.29	0.84–1.98	0.2
Psychiatric disorder	2.11	1.70–2.62	< 0.001	1.47	1.16–1.85	0.001	1.26	0.91–1.75	0.2

For legends, see Table 4