Impact of preoperative frailty on complications, readmissions, and functional recovery following total knee arthroplasty in elderly patients

Table 1 Pre-matching and post-matching standardized mean differences and characteristics of elderly total knee arthroplasty patients with preoperative frailty and non-frail cohort

Characteristic	Frail pre-match (n = 612)	Non-frail pre-match (n = 2512)	SMD pre-match	Frail post-match (n = 512)	Non-frail post-match (n = 2048)	SMD post-match
Age (mean ± SD)	73.5 ± 5.5	71.2 ± 4.8	0.45	72.3 ± 5.1	72.1 ± 4.9	0.04
Gender: Female (%)	65.0	58.0	0.14	60.9	60.4	0.01
Body mass index (mean ± SD)	32.1 ± 4.2	29.8 ± 3.9	0.56	30.5 ± 4.0	30.4 ± 3.9	0.03
American Society of Anesthesiologists III and IV (%)	45.0	25.0	0.42	30.1	29.0	0.02
Diabetes mellitus (%)	55.0	35.0	0.41	40.6	40.1	0.01
Hypertension (%)	80.0	60.0	0.43	69.9	69.5	0.01
Chronic obstructive pulmonary disease (%)	30.0	15.0	0.35	19.9	20.0	0.00

It presents the baseline characteristics and standardized mean differences for the frail and non-frail groups before and after propensity score matching. The post-matching standardized mean differences, which are all < 0.1, confirm the excellent balance achieved between the two groups for the matching covariates: (1) Age; (2) Gender (female); (3) Body mass index; (4) American Society of Anesthesiologists status (III and IV); (5) Diabetes mellitus; (6) Hypertension; and (7) Chronic obstructive pulmonary disease. Pre-match n adjusted for illustration; actual initial frail n = 512 before exclusions. SMD: Standardized mean difference.