Table 2.

Transfusion, complications, in-hospital mortality, and revision risk following unilateral and bilateral TKA

Outcome	Unilateral TKA	Bilateral TKA		p-valuea	p-valueb
		Simultaneous	Staged	Sim. vs. Staged	Sim. vs. Unilat
Blood transfusion (% of patients)	13.3	41	18.6c	< 0.001	< 0.001
Inpatient complication rate (% of patients)d
Cardiac complications	1.3	1.8	1.7c	0.1	< 0.001
Pulmonary embolism	0.7	1.1	0.8c	0.1	0.004
Knee infection	0.06	N/Rg (< 0.14% but ≥0.06%, n < 5)	0.04c	–e	–e
Outpatient complication rate (% of patients) (defined as 90-day re-admission for treatment of same)d
Cardiac complications	0.05	N/Rg (< 0.14% but ≥0.05%, n < 5)	0.04c	–e	–e
Pulmonary embolism	0.14	0.23	0.13c	–e	0.2
Knee Infection	0.6	0.4	0.8c	0.02	0.2
Overall complication rate (inpatient plus outpatient)f (% of patients)d
Cardiac complications	1.4	2.0	1.7c	0.04	< 0.001
Pulmonary embolism	0.8	1.2	0.9c	0.12	0.01
Knee infection	0.7	0.5	0.9c	0.02	0.3
In-hospital mortality (%)h	0.14	0.16	0.06	0.005	0.2
Cumulative revision rate (%)i
Year 1	1.07	0.68	0.63	0.6	< 0.001
Year 2	1.84	1.00	0.96	0.8	< 0.001
Year 3	2.34	1.41	1.37	0.9	< 0.001

^aComparison between bilateral TKA groups (simultaneous vs. staged). p-value after adjusting for patient age at time of surgery, sex, Charlson-based comorbidity, and TKA volume of facility. Significance level set at 0.05.

^bComparison between bilateral TKA groups (simultaneous vs. unilateral). p-value after adjusting for patient age at time of surgery, sex, Charlson-based comorbidity, and TKA volume of facility. Significance level set at 0.05.

^cOutcomes could be at one or both stages, but they were counted if present at least once.

^dPatients discharged before 2009–2010 were excluded due to coding differences (diagnosis cluster was not available).

^ep-value not reported due to a possible bias in the logistic regression model estimates arising from the relative rarity of the observed event.

^fIf a patient experienced a complication event (cardiac, PE, or infection) in hospital and/or was re-admitted with it within 90 days, one combined event was coded.

^gN/R: not reportable. In accordance with the CIHI privacy policy, cells with counts of 1–4 were suppressed. Suppressed cells were included in the totals.

^hMortality during hospitalization for TKA. Patients who had planned staged bilateral TKA but had died after the first stage and before the second stage were included with mortality data for unilateral TKA.

ⁱDoes not include patients who had revision outside of the years included.