Competing risks survival analysis applied to data from the Australian Orthopaedic Association National Joint Replacement Registry

Figures & data

Table 1. Distribution of outcomes for the three study groups

	Censored ^a	Revised ^b	Deceased	Total
FNOF, prosthesis types (75–84 years of age)
Monoblock	2,348 (40%)	225 (4%)	3,229 (56%)	5,802
Unipolar	2,521 (70%)	98 (3%)	990 (27%)	3,609
Bipolar	1,921 (62%)	73 (2%)	1,114 (36%)	3,108
THA	1,373 (76%)	64 (4%)	368 (20%)	1,805
Total	8,163 (57%)	460 (3%)	5,701 (40%)	14,324
FNOF, monoblock (all ages)
Austin Moore	3,310 (34%)	369 (4%)	6,142 (63%)	9,821
Thompson	1,283 (41%)	75 (2%)	1,758 (56%)	3,116
Total	4,593 (36%)	444 (3%)	7,901 (61%)	12,937
OA, THA
Age < 70 years	42,136 (95%)	1,149 (3%)	1,080 (2%)	44,365
Age ≥ 70 years	41,623 (88%)	1,189 (3%)	4,618 (10%)	47,430
Total	83,759 (91%)	2,338 (3%)	5,698 (6%)	91,795

^a right censored due to closure of database for analysis.

^b simple raw proportion, not allowing for censoring.

FNOF: fractured neck of femur; OA: osteoarthritis; THA: total hip arthroplasty.

Figure 1. Estimates of revision by type of prosthesis in patients with FNOF who were aged 75–84 years.

Table 2. Per cent estimates (with 95% confidence interval) of revision in patients aged 75–84 years with FNOF

	1 year	2 years	3 years	4 years	5 years	6 years
Monoblock
At risk	3,512	2,521	1,759	1,108	599	266
KM ^a	3.2 (2.7–3.8)	4.6 (4.0–5.3)	5.6 (4.9–6.5)	5.9 (5.1–6.8)	6.3 (5.5–7.3)	6.6 (5.6–7.8)
CIF ^b	2.6 (2.2–3.1)	3.5 (3.1–4.1)	4.1 (3.6–4.6)	4.2 (3.7–4.8)	4.3 (3.8–4.9)	4.4 (3.9–5.0)
Diff. ^c	0.6	1.1	1.5	1.7	2.0	2.2
RD ^d	21%	30%	38%	40%	46%	50%
Unipolar
At risk	2,180	1,376	805	439	223	71
KM	2.1 (1.6–2.7)	3.1 (2.5–3.9)	3.9 (3.1–4.8)	4.8 (3.7–6.0)	5.6 (4.3–7.3)	6.0 (4.5–8.0)
CIF	1.9 (1.5–2.4)	2.7 (2.1–3.3)	3.2 (2.6–4.0)	3.8 (3.0–4.7)	4.3 (3.3–5.3)	4.5 (3.5–5.7)
Diff.	0.2	0.4	0.6	1.0	1.3	1.5
RD	10%	15%	20%	26%	31%	34%
Bipolar
At risk	2,351	1,868	1,398	951	553	245
KM	1.6 (1.2–2.1)	2.3 (1.7–2.9)	2.7 (2.1–3.5)	3.2 (2.5–4.1)	3.4 (2.6–4.3)	3.4 (2.6–4.3)
CIF	1.5 (1.1–1.9)	2.0 (1.5–2.6)	2.3 (1.8–2.9)	2.7 (2.1–3.3)	2.7 (2.2–3.4)	2.7 (2.2–3.4)
Diff.	0.1	0.3	0.4	0.6	0.6	0.6
RD	9%	14%	17%	21%	23%	23%
THA
At risk	1,238	873	598	379	215	93
KM	2.8 (2.1–3.8)	3.5 (2.7–4.6)	3.9 (3.0–5.1)	4.8 (3.6–6.4)	5.8 (4.3–8.0)	6.5 (4.7–9.1)
CIF	2.7 (2.0–3.6)	3.3 (2.5–4.3)	3.7 (2.8–4.7)	4.3 (3.3–5.6)	5.0 (3.7–6.6)	5.4 (4.0–7.2)
Diff.	0.1	0.2	0.3	0.5	0.8	1.1
RD	4%	6%	8%	12%	17%	20%

^a Kaplan-Meier estimate of cumulative per cent revised.

^b Cumulative incidence function.

^c Difference (bias of the KM estimate).

^d Relative difference (bias of KM estimate relative to the CIF).

Figure 2. Estimates of death by type of prosthesis in patients with FNOF who were aged 75–84 years.

Figure 3. Relative overestimation of KM estimates compared to CIF estimates by years after primary procedure and type of prosthesis; patients were aged 75–84 years with FNOF.

Figure 4. Estimates of revision by type of prosthesis (cementless Austin Moore vs. cemented Thompson) in patients with FNOF.

Table 3. Per cent estimates (with 95% confidence interval) of revision in patients with FNOF who received Austin-Moore or Thompson prostheses

	1 year	2 years	3 years	4 years	5 years	6 years
Austin Moore stem
At risk	5,514	3,893	2,756	1,740	963	403
KM ^a	3.4 (3.0–3.8)	4.7 (4.2–5.3)	5.5 (4.9–6.1)	5.7 (5.2–6.4)	6.2 (5.6–7.0)	6.5 (5.8–7.4)
CIF ^b	2.7 (2.4–3.1)	3.5 (3.1–3.9)	3.8 (3.5–4.3)	3.9 (3.6–4.4)	4.1 (3.7–4.5)	4.2 (3.8–4.6)
Diff. ^c	0.7	1.2	1.6	1.8	2.1	2.4
RD ^d	25%	35%	42%	45%	52%	57%
Thompson stem
At risk	1,905	1,334	865	506	230	96
KM	1.5 (1.1–2.1)	2.5 (1.9–3.3)	3.4 (2.6–4.4)	4.1 (3.2–5.3)	5.6 (4.1–7.5)	5.6 (4.1–7.5)
CIF	1.3 (0.9–1.7)	1.9 (1.5–2.5)	2.3 (1.8–3.0)	2.6 (2.1–3.3)	3.1 (2.4–3.9)	3.1 (2.4–3.9)
Diff.	0.3	0.6	1.1	1.5	2.5	2.5
RD	20%	33%	44%	56%	79%	79%

^a Kaplan-Meier estimate of cumulative per cent revised.

^b Cumulative incidence function.

^c Difference (bias of the KM estimate).

^d Relative difference (bias of KM estimate relative to the CIF).

Figure 5. Estimates of death by type of prosthesis (cementless Austin Moore vs. cemented Thompson) in patients with FNOF.

Figure 6. Estimates of revision by age group in patients with OA and THA.

Figure 7. Estimates of death by age group in patients with OA and THA.

Table 4. Per cent estimates (with 95% confidence interval) of revision in patients with osteoarthritis who underwent total hip replacement–by age group

	1 year	2 years	3 years	4 years	5 years	6 years
Age < 70 years
At risk	35,335	27,994	21,454	15,322	9,737	4,714
KM ^a	1.4 (1.3–1.5)	2.1 (2.0–2.3)	2.7 (2.5–2.8)	3.0 (2.9–3.2)	3.6 (3.4–3.8)	4.1 (3.9–4.4)
CIF ^b	1.4 (1.3–1.5)	2.1 (2.0–2.3)	2.6 (2.5–2.8)	3.0 (2.8,3.2)	3.5 (3.3–3.7)	4.1 (3.8–4.4)
Diff. ^c	0.003	0.01	0.02	0.03	0.05	0.07
RD ^d	0.3%	0.5%	0.8%	1.0%	1.4%	1.8%
Age ≥ 70 years
At risk	38,089	30,254	22,853	16,141	10,059	4,636
KM	1.6 (1.5–1.7)	2.1 (2.0–2.3)	2.5 (2.4–2.7)	2.9 (2.8–3.1)	3.3 (3.1–3.5)	3.7 (3.5–4.0)
CIF	1.6 (1.5–1.7)	2.1 (2.0–2.2)	2.5 (2.3–2.6)	2.8 (2.7–3.0)	3.2 (3.0–3.4)	3.5 (3.3–3.7)
Diff.	0.01	0.03	0.06	0.10	0.15	0.22
RD	0.9%	1.4%	2.3%	3.4%	4.6%	6.2%

^a Kaplan-Meier estimate of cumulative per cent revised.

^b Cumulative incidence function.

^c Difference (bias of the KM estimate).

^d Relative difference (bias of KM estimate relative to the CIF.