Preoperative Nutritional Laboratory Tests Are Infrequently Obtained and Weakly Associated With 90-Day Reoperation...

Preoperative optimization is an established practice for reducing complications following total knee arthroplasty (TKA). Several publications have recommended specific laboratory studies for nutritional assessment. We aimed to evaluate the frequency these labs have obtained and their association with 90-day reoperation rates.

A large dataset including over 246 million patients was used to identify 1,164,711 patients undergoing TKA from 2015 to 2025. The incidence of having albumin, prealbumin, transferrin, and total lymphocyte count laboratory values within 90 days prior to TKA was assessed. The multivariable associations of lab values dichotomized as low versus normal with 90-day reoperation were evaluated using logistic regressions to adjust for age, body mass index, sex, race, hemoglobin, and comorbidity load, with odds ratios and 95% confidence intervals (CIs) reported.

Nutritional laboratory values were infrequently obtained within 90 days prior to TKA: albumin (38%), prealbumin (3%), transferrin (2%), and total lymphocyte count (38%). When measured, these values were rarely abnormal: 4.4% for albumin, 2.5% for prealbumin, 7.5% for transferrin, and 29.6% for total lymphocyte count. In total, 21,972 patients (1.9%) had a reoperation within 90 days postoperatively. After adjusting for potential confounders, abnormal laboratory values demonstrated only a weak association for albumin (OR [odds ratio] = 1.57; 95% CI, 1.45 to 1.70), transferrin (OR = 1.47; 95% CI, 1.12 to 1.93), and total lymphocyte count (OR = 1.08, 95% CI, 1.04 to 1.13). Prealbumin demonstrated the strongest, though still modest, association (OR = 2.35; 95% CI, 1.69 to 3.27).

Despite recommendations and attention, nutritional studies are infrequently ordered before TKA and rarely abnormal. Although some nutritional markers had an association with 90-day reoperations, the extent to which this represents selection bias is unknown. Further research is needed to define the clinical utility of preoperative nutritional testing and identify which patients benefit from screening.