Body mass index and risk of perioperative cardiovascular adverse events and mortality in 34,744 Danish patients undergoing hip or knee replacement

Figures & data

Table 1. Baseline characteristics

	Underweight n = 353	Normal weight n = 9,859	Overweight n = 13,787	Obese 1 n = 7,450	Obese 2 n = 3,295
Body mass index, kg/m^2 ^a	17.6 (14.1–18.5)	23.3 (18.5–25.0)	27.4 (25.0–30.0)	31.9 (30.0–35.0)	37.6 (35.0–50.0)
Age, years ^b	75 (65–82)	75 (65–82)	71 (64–78)	67 (62–74)	65 (59–71)
Sex, male	33 (9%)	3,382 (34%)	6,625 (48%)	3,153 (42%)	1,113 (34%)
Total hip replacement	307 (87%)	6,676 (68%)	7,765 (56%)	3,250 (44%)	1,130 (34%)
Surgery time, min	70 (55–90)	70 (55–87)	70 (55–89)	75 (60–93)	80 (65–100)
ASA score 1	68 (19%)	3,081 (31%)	3,610 (26%)	1,272 (17%)	236 (7%)
ASA score 2	208 (59%)	5,586 (57%)	8,532 (62%)	5,052 (68%)	2,042 (62%)
ASA score 3+	68 (19%)	1,061 (11%)	1,491 (11%)	1,044 (14%)	980 (30%)
Heart failure	8 (3%)	196 (2%)	287 (2%)	185 (2%)	86 (3%)
Current smoker	119 (33%)	1,786 (18%)	2,059 (15%)	1,033 (14%)	446 (14%)
Cerebrovascular disease	18 (14%)	311 (3%)	351 3%)	185 (2%)	78 (2%)
COPD	24 (7%)	233 (2%)	264 (2%)	171 (2%)	113 (3%)
Anemia	19 (5%)	266 (3%)	229 (2%)	108 (1.4%)	60 (2%)
Renal disease	3 (0.8%)	78 (0.8%)	90 (0.7%)	58 (0.8%)	29 (0.9%)
Peripheral artery disease	5 (1%)	63 (0.6%)	74 (0.5%)	46 (0.6%)	25 (0.8%)
Acute myocardial infarction	7 (2%)	155 (2%)	242 (2%)	146 (2%)	51 (2%)
Atrial fibrillation	21 (6%)	444 (5%)	605 (4%)	342 (5%)	152 (5%)
Statin treatment	51 (14%)	1,835 (19%)	3,454 (25%)	2,256 (30%)	961 (29%)
Diabetes	10 (3%)	360 (4%)	943 (6.8%)	907 (12%)	607 (18%)
Calcium channel blockers	40 (11%)	1,618 (16%)	2,636 (19%)	1,765 (24%)	742 (23%)
ACE inhibitors	76 (22%)	2,416 (25%)	4,398 (32%)	3,114 (42%)	1,542 (47%)
Thiazides	44 (12%)	1,359 (14%)	2,512 (18%)	1,563 (21%)	808 (25%)
Aldosterone blockers ^c	14 (4%)	142 (1%)	237 (2%)	181 (2%)	112 (3%)
Clopidogrel	4 (1%)	114 (1%)	170 (1%)	107 (1%)	24 (0.7%)
Beta blocker	39 (11%)	1,277 (13%)	2,336 (17%)	1,525 (20%)	727 (22%)
Vitamin K antagonists	15 (4%)	413 (4%)	642 (5%)	352 (5%)	166 (5%)
Aspirin	56 (16%)	1,839 (19%)	2,912 (21%)	1,743 (23%)	763 (23%)
Alcohol, 0 drinks/week	160 (45%)	3,649 (37%)	4,927 (36%)	2,981 (40%)	1,582 (48%)
Alcohol, 1–14 drinks/week	107 (30%)	3,791 (38%)	5,259 (38%)	2,639 (35%)	948 (29%)
Alcohol, 15–21 drinks/week	16 (5%)	499 (5%)	903 (7%)	403 (5%)	127 (4%)
Alcohol, > 21 drinks/week	23 (7%)	616 (6%)	962 (7%)	516 (7%)	228 (7%)
Alcohol, unknown	47 (13%)	1,304 (13%)	1,734 (13%)	911 (12%)	410 (12%)
No loop diuretics (%)	319 (90%)	9,255 (94%)	12,793 (93%)	6,606 (89%)	2,713 (82%)
Loop diuretics ≤ 40 mg/day	17 (5%)	346 (4%)	559 (4%)	446 (6%)	293 (9%)
Loop diuretics 41–80 mg/day	10 (3%)	146 (2%)	246 (2%)	230 (3%)	150 (5%)
Loop diuretics 81–160 mg/day	7 (2%)	43 (0.4%)	76 (0.6%)	87 (1%)	62 (2%)
Loop diuretics > 160 mg/day	0 (0%)	69 (0.7%)	113 (0.8%)	81 (1%)	77 (2%)

^a presented as median (min–max)

^b presented as median (interquartile range).

^c e.g. spironolactone

Table 2. Crude numbers of events and adjusted hazard ratios associated with different BMI groups for the individual endpoints

	30-day MACE	30-day mortality	30-day CV mortality	1-year mortality	1-year CV mortality
Numbers events
Underweight	4/353 (1.1%)	6/353 (1.7%)	2/353 (0.6%)	31/353 (8.8%)	6/353 (1.7%)
Normal weight	78/9,859 (0.8%)	46/9,859 (0.5%)	31/9,859 (0.3%)	229/9,859 (2.3%)	104/9,859 (1.1%)
Overweight	77/13,787 (0.6%)	29/13,787 (0.2%)	18/13,787 (0.1%)	183/13,787 (1.3%)	83/13,787 (0.6%)
Obese 1	59/7,450 (0.8%)	21/7,450 (0.3%)	17/7,450 (0.2%)	95/7,450 (1.3%)	49/7,450 (0.7%)
Obese 2	14/3,295 (0.4%)	9/3,295 (0.3%)	6/3,295 (0.2%)	44/3,295 (1.3%)	23/3,295 (0.7%)
	Hazard ratio	Hazard ratio	Hazard ratio	Hazard ratio	Hazard ratio
Model 1 (ref = overweight)
Underweight	2.0 (0.7–5.4)	7.7 (3.1–19)	4.1 (0.9–18)	5.7 (3.8–8.4)	2.5 (1.09–5.9)
Normal weight	1.3 (0.94–1.8)	2.0 (1.2–3.1)	2.07 (1.1–3.8)	1.6 (1.3–1.9)	1.5 (1.1–2.06)
Obese 1	1.7 (1.2–2.4)	1.6 (0.93–2.9)	2.1 (1.08–4.1)	1.2 (0.9–1.5)	1.4 (0.97–2.0)
Obese 2	1.2 (0.67–2.1)	2.3 (1.08–5.0)	2.4 (0.94–6.2)	1.7 (1.2–2.4)	2.2 (1.4–3.5)
Model 2 (ref = overweight)
Underweight	1.6 (0.58–4.4)	7.05 (2.8–18)	3.7 (0.83–17)	5.2 (3.5–7.7)	2.3 (0.99–5.3)
Normal weight	1.3 (0.93–1.8)	1.9 (1.2–3.1)	2.02 (1.1–3.7)	1.6 (1.3–1.9)	1.6 (1.2–2.1)
Obese 1	1.6 (1.1–2.3)	1.6 (0.9–2.8)	2.0 (1.01–3.9)	1.2 (0.89–1.5)	1.3 (0.9–1.9)
Obese 2	1.1 (0.62–2.0)	2.07 (0.96–4.4)	2.1 (0.82–5.4)	1.5 (1.09–2.1)	1.9 (1.2–3.03)
Model 3 (ref = overweight)
Underweight	1.6 (0.58–4.5)	7.2 (2.9–18)	3.8 (0.84–17)	5.3 (3.6–7.9)	2.4 (1.02–5.5)
Normal weight	1.3 (0.95–1.8)	2.0 (1.2–3.2)	2.05 (1.1–3.7)	1.6 (1.3–2.0)	1.6 (1.2–2.2)
Obese 1	1.6 (1.1–2.2)	1.5 (0.87–2.7)	2.0 (1.0–3.8)	1.1 (0.87–1.4)	1.3 (0.92–1.9)
Obese 2	1.04 (0.58–1.9)	1.9 (0.9–4.2)	2.05 (0.8–5.3)	1.4 (1.01–2.0)	1.8 (1.1–2.9)
Model 4 (ref = overweight)
Underweight	1.2 (0.44–3.3)	7.0 (2.8–15)	3.8 (0.84–17)	5.2 (3.5–7.8)	2.4 (1.03–5.6)
Normal weight	0.77 (0.56–1.07)	2.0 (1.2–3.2)	2.05 (1.1–3.7)	1.6 (1.3–2.0)	1.6 (1.2–2.2)
Obese 1	1.2 (0.84–1.7)	1.5 (0.87–2.7)	2.0 (1.0–3.8)	1.1 (0.87–1.4)	1.3 (0.92–1.9)
Obese 2	0.8 (0.44–1.5)	1.9 (0.9–4.2)	2.06 (0.8–5.3)	1.4 (1.01–2.0)	1.8 (1.1–2.9)

MACE: major adverse cardiovascular events (ischemic stroke, acute myocardial infarction, and cardiovascular death); CV: cardiovascular.

Model 1 was adjusted for age, gender, and hip vs. knee replacement surgery. Model 2 was additionally adjusted for heart failure, previous myocardial infarction, chronic ischemic heart disease, atrial fibrillation, peripheral artery disease, cerebrovascular disease, chronic obstructive pulmonary disease, and renal disease. Model 3 was additionally adjusted for diabetes. Model 4 was additionally adjusted for cemented vs. non-cemented prosthesis.

Splines of hazard ratios associated with BMI levels. Analyses were adjusted for age, gender, and type of surgery (i.e. knee vs. hip replacement surgery).

Table 3. Hazard ratios associated with other variables from multivariable Cox regression models

	30-day mortality	30-day CV mortality	30-day MACE	1-year mortality	1-year CV mortality
Male sex	2.2 (1.5–3.3)	2.09 (1.3–3.4)	1.8 (1.4–2.3)	1.7 (1.5–2.07)	2.02 (1.6–2.6)
Age, per 1 year increase	1.09 (1.06–1.1)	1.09 (1.06–1.1)	1.07 (1.05–1.09)	1.07 (1.06–1.08)	1.09 (1.07–1.10)
COPD	1.7 (0.84–3.6)	1.73(0.74–4.04)	1.7 (1.02–2.9)	2.4 (1.80–3.3)	1.7 (1.08–2.7)
Renal disease	1.6 (0.97–2.5)	1.60 (0.93–2.7)	1.4 (0.94–2.0)	1.9 (1.6–3.3)	1.9 (1.4–2.4)
Peripheral artery disease	3.5 (1.4–8.4)	5.0 (2.0–13)	2.1 (1.04–4.2)	1.7 (0.94–2.9)	2.4 (1.2–4.6)
Cerebrovascular disease	3.02 (1.7–5.4)	4.05 (2.1–7.7)	6.8 (4.90–9.4)	1.5 (1.1–2.2)	2.3 (1.5–3.4)
Heart failure	2.07 (1.03–4.2)	3.3 (1.5–7.1)	1.5 (0.87–2.5)	1.4 (1.0–2.0)	1.9 (1.3–2.9)
Ischemic heart disease	1.5 (0.81–4.2)	1.1 (0.53–2.4)	1.8 (1.2–2.70)	1.5 (1.1–1.9)	1.7 (1.2–2.4)
Acute myocardial infarction	1.02 (0.39–2.7)	1.6 (0.57–4.3)	2.01 (1.2–3.4)	0.81 (0.50–1.3)	1.1 (0.63–2.0)
Atrial fibrillation	0.7 (0.34–1.4)	0.5 (0.19–1.3)	0.49 (0.28–0.86)	1.4 (1.09–1.9)	1.6 (1.08–2.3)
Diabetes	1.7 (0.97–2.9)	1.3 (0.63–2.7)	1.6 (1.08–2.3)	1.6 (1.2–2.05)	1.7 (1.2–2.4)
Total hip vs. knee replacement	0.99 (0.64–1.6)	0.72 (0.41–1.3)	1.01 (0.75–1.4)	1.4 (1.2–1.7)	1.2 (0.89–1.6)
Cemented vs. uncemented arthroplasty	1.3 (0.77–2.2)	0.98 (0.51–1.9)	1.3 (0.89–1.8)	1.1 (0.98–1.4)	0.96 (0.7–1.3)

Hazard ratios are derived from model 4 (see under statistics section).