The association of iron deficiency anemia and perioperative complications following revision total knee arthroplasty.

BACKGROUND

Recent studies show an increase in the prevalence of iron deficiency anemia (IDA) worldwide and a concomitant rise in the number of revision total knee arthroplasty (RTKA). The literature evaluating the association between IDA and perioperative outcomes following RTKA are limited. Therefore, the purpose of this study was to determine whether IDA patients undergoing RTKA have higher rates of (1) in-hospital lengths of stay (LOS), (2) complications; and (3) costs.

METHODS

Using International Classification of Disease, Ninth Revision (ICD-9) and Current Procedural Terminology (CPT), a retrospective query was performed from January 1, 2005 to March 31, 2014. The inclusion criteria consisted of those patients who have IDA undergoing RTKA. Study group patients were 1:5 ratio matched to a comparison cohort by age, sex, and various comorbidities: coronary artery disease, chronic obstructive pulmonary disease, diabetes mellitus, hyperlipidemia, hypertension, obesity, and tobacco use, yielding a total of 106,534 patients within the study (n = 17,784) and control (n = 88,750) cohorts. Outcomes assessed included: in-hospital LOS, costs of care, and medical complications. Multivariate Logistic regression analyses were used to calculate the odds-ratios (OR) and respective 95% confidence intervals (95%CI). Welch's t-tests were used to compare in-hospital LOS and costs of care. Following Bonferroni-correction, a P-value less than 0.001 was considered statistically significant.

RESULTS

IDA patients undergoing RTKA were found to have significantly higher in-hospital LOS (4-days vs. 3-days, P < 0.0001). Additionally, IDA patients were found to have significantly higher odds (OR) of medical complications (OR: 5.29, P < 0.0001) such as: pneumonia (OR: 6.86, P < 0.0001), respiratory failures (OR: 5.95, P < 0.0001), myocardial infarctions (OR: 4.31, P < 0.0001) and other complications. Furthermore, IDA patients incurred significantly higher day of surgery ($16,976.01 vs. $14,515.81, P < 0.0001) and 90-day costs ($22,548.71 vs. $16,819.15, P < 0.0001).

CONCLUSION

The study demonstrated IDA patients undergoing RTKA have higher rates of in-hospital LOS, costs of care, and medical complications. Orthopedic surgeons and other healthcare professionals can use this information to adequately educate these patients of the potential complications following their procedure.