Table 3

Crude incidence of total hip arthroplasty by morbidity measure

Morbidity scale	Category	THA (N)	PYR	Incidence /100PYR	95% CI
Charlson Comorbidity Index	0	7878	64 676	12.2	11.9 to 12.4
	1	1160	11 729	9.9	9.3 to 10.5
	2	1115	10 096	11.0	10.4 to 11.7
	3+	795	8628	9.2	8.6 to 9.9
Count of chronic diseases	0	4248	34 744	12.2	11.9 to 12.6
	1	3631	30 613	11.9	11.5 to 12.2
	2	1955	17 482	11.2	10.7 to 11.7
	3+	1114	12 289	9.1	8.5 to 9.6
Count of medications prescribed	0–4	4674	38 337	12.2	11.8 to 12.5
	5–7	2911	24 489	11.9	11.5 to 12.3
	8–12	2421	22 576	10.7	10.3 to 11.2
	13+	942	9726	9.7	9.1 to 10.3
Count of contacts with primary care	0–7	4946	42 662	11.6	11.3 to 11.9
	8–11	2559	21 483	11.9	11.5 to 12.4
	12–17	1939	16 902	11.5	11.0 to 12.0
	18+	1504	14 080	10.7	10.1 to 11.2
Electronic Frailty Index	0–4	8373	69 541	12.0	11.8 to 12.3
	5–8	2249	21 349	10.5	10.1 to 11.0
	9–12	303	3839	7.9	7.0 to 8.8
	13+	23	399	5.8	3.4 to 8.1