Obesity and postoperative opioid utilization after total knee arthroplasty: A propensity-matched analysis

Table 1 Demographics and medical comorbidities for body mass index ≥ 40 vs body mass index < 30 cohorts before and after propensity score matching, n (%)/mean ± SD

	Before PSM				After PSM
	BMI ≥ 40 (n = 883)	BMI < 30 (n = 3835)	P value	SMD	BMI ≥ 40 (n = 807)	BMI < 30 (n = 807)	P value	SMD
Age	60.5 8.4	69.5 10.0	< 0.001	0.968	60.9 8.2	60.6 8.9	0.522	0.032
Race
White	612 (73.3)	2953 (80.9)	< 0.001	0.182	599 (74.2)	605 (75.0)	0.732	0.017
Black or African American	156 (18.7)	274 (7.5)	< 0.001	0.336	143 (17.7)	138 (17.1)	0.743	0.016
Asian	10 (1.2)	108 (3.0)	0.004	0.124	10 (1.2)	0 (0.0)	0.002	0.158
Native Hawaiian or Other Pacific Islander	0 (0.0)	10 (0.3)	0.130	0.074	0 (0.0)	0 (0.0)	> 0.999	< 0.001
American Indian or Alaska Native	10 (1.2)	10 (0.3)	< 0.001	0.108	10 (1.2)	10 (1.2)	> 0.999	< 0.001
Other race	10 (1.2)	63 (1.7)	0.276	0.044	10 (1.2)	10 (1.2)	> 0.999	< 0.001
Unknown race	54 (6.5)	243 (6.7)	0.842	0.008	53 (6.6)	54 (6.7)	0.920	0.005
Sex
Male	200 (24.0)	1418 (38.8)	< 0.001	0.325	198 (24.5)	210 (26.0)	0.492	0.034
Female	635 (76.0)	2231 (61.1)	< 0.001	0.326	609 (75.5)	597 (74.0)	0.492	0.034
Unknown	0 (0.0)	10 (0.3)	0.130	0.074	0 (0.0)	0 (0.0)	> 0.999	< 0.001
Medical comorbidities
Mood (affective) disorders	84 (10.1)	231 (6.3)	< 0.001	0.136	79 (9.8)	64 (7.9)	0.189	0.065
Anxiety disorders	66 (7.9)	246 (6.7)	0.233	0.045	62 (7.7)	51 (6.3)	0.283	0.053
Chronic pain syndrome	10 (1.2)	13 (0.4)	0.002	0.096	10 (1.2)	10 (1.2)	> 0.999	< 0.001
Chronic pain	79 (9.5)	259 (7.1)	0.020	0.086	75 (9.3)	70 (8.7)	0.663	0.022
Diabetes mellitus	140 (16.8)	462 (12.7)	0.002	0.116	135 (16.7)	114 (14.1)	0.148	0.072
Hyperlipidemia (unspecified)	146 (17.5)	861 (23.6)	< 0.001	0.152	144 (17.8)	111 (13.8)	0.024	0.112
Pure hypercholesterolemia	66 (7.9)	464 (12.7)	< 0.001	0.159	65 (8.1)	49 (6.1)	0.120	0.077
Essential (primary) hypertension	293 (35.1)	1366 (37.4)	0.207	0.049	280 (34.7)	220 (27.3)	0.001	0.161
CKD	17 (2.0)	126 (3.5)	0.036	0.087	17 (2.1)	12 (1.5)	0.349	0.047
Nicotine dependence	18 (2.2)	78 (2.1)	0.973	0.001	18 (2.2)	16 (2.0)	0.729	0.017
Coronary artery disease	45 (5.4)	314 (8.6)	0.002	0.126	43 (5.3)	39 (4.8)	0.650	0.023

BMI: Body mass index; CKD: Chronic kidney disease; PSM: Propensity score matching; SMD: Standardized mean difference.

Table 2 Odds of opioid prescription between patients with different body mass index levels within 2 years of total knee arthroplasty after propensity score matching, n (%)

Direct comparison	Opioid prescription odds	OR (95%CI)	P value
BMI ≥ 30 kg/m² (n = 2779)	1298 (46.7)	1.174 (1.056-1.305)	0.003
BMI < 30 kg/m² (n = 2779)	1188 (42.7)
BMI ≥ 40 kg/m² (n = 734)	340 (46.3)	1.011 (0.823-1.241)	0.917
BMI 35-39.9 kg/m² (n = 734)	338 (46.0)
BMI ≥ 40 kg/m² (n = 792)	358 (45.2)	1.042 (0.854-1.270)	0.686
BMI 30-34.9 kg/m² (n = 792)	350 (44.2)
BMI ≥ 40 kg/m² (n = 807)	366 (45.4)	1.146 (0.941-1.395)	0.175
BMI < 30 kg/m² (n = 807)	339 (42.0)
BMI 35-39.9 kg/m² (n = 1126)	529 (47.0)	1.070 (0.907-1.263)	0.422
BMI 30-34.9 kg/m² (n = 1126)	510 (45.3)
BMI ≥ 40 kg/m² (n = 750)	327 (43.6)	1.085 (0.884-1.332)	0.433
BMI < 40 kg/m² (n = 750)	312 (41.6)

BMI: Body mass index; OR: Odds ratio.

Table 3 Number of opioid prescriptions between patients of different body mass index levels within 2 years of total knee arthroplasty after propensity score matching, mean ± SD

Direct comparison	No. opioid prescriptions	Median	P value
BMI ≥ 30 kg/m² (n = 2779)	4.18 ± 4.5	3	0.207
BMI < 30 kg/m² (n = 2779)	3.96 ± 4.1	3
BMI ≥ 40 kg/m² (n = 734)	4.76 ± 7.0	3	0.614
BMI 35-39.9 kg/m² (n = 734)	4.52 ± 5.1	3
BMI ≥ 40 kg/m² (n = 792)	4.75 ± 6.9	3	0.366
BMI 30-34.9 kg/m² (n = 792)	4.35 ± 4.4	3
BMI ≥ 40 kg/m² (n = 807)	4.74 ± 6.8	3	0.596
BMI < 30 kg/m² (n = 807)	4.50 ± 5.1	3
BMI 35-39.9 kg/m² (n = 1126)	4.62 ± 5.0	3	0.436
BMI 30-34.9 kg/m² (n = 1126)	4.39 ± 4.7	3
BMI ≥ 40 kg/m² (n = 750)	4.73 ± 6.9	3	0.478
BMI < 40 kg/m² (n = 750)	4.39 ± 5.0	3

BMI: Body mass index.