Table 1. Distribution of sex, ASA grade, fixation type, and age in datasets with complete and incomplete BMI records.

		Complete (N = 493,710)		Incomplete (N = 384,481)
		N	%	N	%
Sex	Female	283,161	57.4	221,450	57.6
	Male	210,549	42.6	163,030	42.4
	Missing	0	0	1	0
ASA grade	P1	48,134	9.75	51,405	13.4
	P2	362,745	73.5	272,432	70.9
	P3	81,342	16.5	58,931	15.3
	P4–P5	1,489	0.3	1,713	0.45
Fixation type	Cemented	473,303	95.9	355,270	92.4
	Uncemented	17,380	3.52	23,340	6.07
	Hybrid	3,027	0.61	5,871	1.53
Age in years	<50	9,883	2	8,268	2.15
	50–54	20,024	4.06	14,131	3.68
	55–59	40,688	8.24	31,392	8.16
	60–64	72,014	14.6	54,850	14.3
	65–69	96,459	19.5	71,053	18.5
	70–74	98,844	20	77,452	20.1
	75–79	85,619	17.3	70,086	18.2
	80–84	50,293	10.2	40,999	10.7
	≥85	19,886	4.03	16,250	4.23

ASA, American Society of Anaesthesiologists; BMI, body mass index.