gms | German Medical Science

Objectives: With an ageing population and a growing number of primary arthroplasties performed, the frequency of revision surgeries is predicted to further increase. Anemia has been shown to be a modifiable pre-operative, patient factor associated with outcome following arthroplasty. The aims of this study were to 1) ascertain the prevalence of preoperative anemia in patients undergoing primary and revision hip and knee arthroplasty at a tertiary referral center and 2) to test the association with outcome and whether it differs between primary and revision cases.

Methods: All hip and knee primary and revision arthroplasties performed at a Canadian academic, tertiary-care, arthroplasty center between 2012 and 2017 were included in this study. The study group consisted of 5,944 patients, of which 5,251 were primary Total Hip and Knee Arthroplasties or Hip Resurfacings and 693 were revision arthroplasties (65% hip/35% knee). Anemia was classified as per WHO definition (hemoglobin <130 g/L for men and <120 g/L for women). All anemic patients were grouped into mild (110 g/L – lower limit of normal as per gender), moderate (80–109 g/L), or severe (<80 g/L) anemia. Length of stay, perioperative transfusion rate, 90-day readmission, the overall complication rate and reoperation-rates were recorded. The effect of preoperative anemia and the effect of the severity of the anemia were evaluated through multivariable regression analysis controlling for relevant covariates.

Results: Preoperatively, 15% (786/5251) of the primary patients were anemic, of which 79% were mild, 21% moderate and 0.3% severe anemic. In contrast, 47% of the revision arthroplasty patients were anemic preoperatively, of which 44% were mild, 54% moderate and 2% severe anemic. Anemic revision patients were 3.1 times more likely (95% CI: 1.47–6.33) to obtain one or more blood transfusion during the hospital stay, compared to a 4.9 times higher risk in primary patients. The odds ratio to sustain any postoperative complication if anemic was 1.5 times higher (95% CI: 0.73–3.16) in revision patients and 1.7 in primary cases. In addition, the 90-day readmission rate among both groups was 1.6 times higher in anemic patients. Furthermore, anemic revision patients had a 5.3 days longer length of stay (95% CI: 2.63–7.91), compared to only 1 additional day in anemic primary patients (95% CI: 0.69–1.34).

Conclusion: In this study cohort, the prevalence of anemia in patients awaiting revision arthroplasty was 3 times higher than in primary arthroplasty patients. Preoperative anemia was associated with similarly, inferior outcome in both groups. To reduce postoperative complications and the “burden” associated with anemia, these findings strongly recommend optimizing the preoperative hemoglobin in all arthroplasty patients. However, revision patients are affected more frequently, and particular attention must therefore be taken to this growing group in the future.