Factors predisposing to claims and compensations for patient injuries following total hip and knee arthroplasty

Figures & data

Table 1. Descriptive statistics on THA and TKA patients operated on in the public sector in Finland from 1998 through 2003. Values are mean (SD) or n (%)

		All patients		Patients having filed a claim
		THA ^a	TKA ^b	THA ^a	TKA ^b
	Description	(n =16,646)	(n = 17,535)	(n = 408)	(n = 437)
Explanatory variable
Age over 65	Aged over 65 = 1, aged 65 or less = 0	10,680 (64%)	13,260 (76%)	206 (50%)	296 (68%)
Male	Male = 1, female = 0	7,144 (43%)	4,784 (27%)	159 (39%)	108 (25%)
Charlson index	A value from 0 to 11 (in this study population) depending on the number and/or severity of comorbidities	0.38 (0.79)	0.44 (0.85)	0.43 (0.77)	0.53 (0.97)
Cemented	Both components of the prosthesis cemented = 1, otherwise 0	8,091 (49%)	16,314 (93%)	160 (39%)	405 (93%)
Hybrid	Either component of the prosthesis cemented and the other not = 1, otherwise 0	2,710 (16%)	808 (5%)	70 (17%)	26 (6%)
Previous THA (TKA)	Contralateral primary THA (TKA) before current THA (TKA) = 1, otherwise 0	1,870 (11%)	1,806 (10%)	48 (12%)	35 (8%)
THA (TKA) before change in law	THA (TKA) before the amendment to the Patient Injury Act = 1, otherwise 0	3,662 (22%)	3,561 (20%)	87 (21%)	82 (19%)
Volume < 200	THA (TKA) performed at a hospital with less than 200 of these operations per year = 1, otherwise 0; reference category for volume 200–300 and volume > 300	12,715 (76%)	12,902 (74%)	297 (73%)	324 (74%)
Volume 200–300	THA (TKA) performed at a hospital with more than 200 but less than 300 of these operations per year = 1, otherwise 0	3,042 (18%)	2,587 (15%)	90 (22%)	67 (15%)
Volume > 300	THA (TKA) performed at a hospital with more than 300 of these operations per year = 1, otherwise 0	889 (5%)	2,046 (12%)	21 (5%)	46 (11%)
Explained variable
Claim	Filed a claim = 1, otherwise 0	408 (2.5%)	437 (2.5%)	–	–
Outcome of claim
Treatment injury	Obtained compensation for a treatment injury = 1, otherwise 0	–	–	148 (36%)	102 (23%)
Infection injury	Obtained compensation for an infection injury = 1, otherwise 0	–	–	50 (12%)	80 (18%)
No compensation	Did not obtain any compensation = 1, otherwise 0			210 (51%)	255 (58%)

^a THA: total hip arthroplasty.

^b TKA: total knee arthroplasty.

Stages in the statistical analysis; the first stage used logistic regression analysis and the second multinomial logistic regression analysis.

Table 2. Results of the first stage using logistic regression analysis^a

		THA ^b			TKA ^c
		(n = 16,646)			(n = 17,535)
Variable	OR ^d	95% CI	p-value	OR ^d	95% CI	p-value
Age over 65	0.57	0.46–0.72	< 0.001	0.65	0.53–0.80	< 0.001
Male	0.74	0.60–0.91	0.004	0.82	0.66–1.03	0.09
Charlson index	1.17	1.04–1.31	0.008	1.14	1.03–1.26	0.01
Cemented	0.77	0.60–0.99	0.04	1.70	0.75–3.85	0.2
Hybrid	0.92	0.69–1.23	0.6	2.23	0.91–5.47	0.08
Previous THA (TKA)	1.15	0.85–1.57	0.4	0.80	0.56–1.13	0.2
THA (TKA) before change in law	0.96	0.75–1.22	0.7	0.92	0.72–1.18	0.5
Volume 200–300	1.29	1.01–1.64	0.04	1.02	0.78–1.34	0.9
Volume > 300	1.02	0.65–1.62	0.9	0.85	0.62–1.17	0.3

^a Explained variable 1 if the patient filed a claim, otherwise 0.

^b THA: total hip arthroplasty.

^c TKA: total knee arthroplasty.

^d OR: odds ratio.

Table 3. Results of the second stage using multinomial logistic regression analysis^a

		THA ^b			TKA ^c
Outcome of claim		(n = 408)			(n = 437)
Variable	RRR ^d	95% CI	p-value	RRR ^d	95% CI	p-value
Treatment injury
Age over 65	0.64	0.39–1.05	0.08	0.57	0.34–0.94	0.03
Male	1.08	0.69–1.69	0.7	0.74	0.41–1.34	0.3
Charlson index	1.10	0.84–1.45	0.5	0.99	0.78–1.27	1.0
Cemented	1.25	0.73–2.15	0.4	0.37	0.05–2.79	0.3
Hybrid	0.93	0.49–1.76	0.8	0.12	0.01–1.26	0.08
Previous THA (TKA)	1.58	0.82–3.03	0.2	2.46	1.00–6.07	0.05
THA (TKA) before change in law	1.05	0.62–1.80	0.9	1.39	0.76–2.54	0.3
Volume 200–300	0.97	0.58–1.63	0.9	0.64	0.32–1.29	0.2
Volume > 300	1.03	0.39–2.69	1.0	0.24	0.08–0.72	0.01
Infection injury
Age over 65	1.03	0.49–2.18	0.9	0.96	0.54–1.73	0.9
Male	1.83	0.96–3.49	0.07	2.07	1.18–3.64	0.01
Charlson index	0.86	0.55–1.34	0.5	0.99	0.75–1.30	0.9
Cemented	2.00	0.89–4.50	0.09	0.26	0.03–1.97	0.2
Hybrid	1.13	0.43–3.02	0.8	0.39	0.04–3.60	0.4
Previous THA (TKA)	1.23	0.46–3.27	0.7	4.02	1.70–9.55	0.002
THA (TKA) before change in law	2.02	1.00–4.09	0.05	1.86	0.98–3.53	0.06
Volume 200–300	0.95	0.44–2.05	0.9	1.49	0.74–2.99	0.3
Volume > 300	0.86	0.18–4.14	0.8	0.97	0.41–2.32	1.0

^a Explained variable 0 if the patient did not obtain any compensation, 1 if the patient obtained compensation for a treatment injury, 2 if the patient obtained compensation for an infection injury; reference category = 0.

^b THA: total hip arthroplasty.

^c TKA: total knee arthroplasty.

^d RRR: relative risk ratio.