Preoperative anaemia and newly diagnosed cancer 1 year after elective total hip and knee arthroplasty

Background Preoperative anaemia is a well‐established risk factor for use of blood transfusions and postoperative morbidity. Consequently, focus on preoperative evaluation of haemoglobin levels is increasing. In this context, iron deficiency anaemia may be a symptom of undiscovered gastrointestinal (GI) cancer requiring further investigation. However, the association between preoperative anaemia and cancer 1 year after elective total hip (THA) and total knee arthroplasty (TKA) is unknown. We evaluated 1‐year cancer diagnoses, particularly GI cancers, in anaemic and non‐anaemic THA and TKA patients. Study Design and Methods A prospective database on preoperative patient characteristics from six Danish orthopaedic centres was cross‐referenced with the Danish Cancer Registry for information on diagnoses of new cancers 1 year after surgery. Crude cancer risk estimates were calculated using chi‐square and Fisher's exact test in the total study cohort. Adjusted risk estimates were obtained using propensity scores and the Mantel–Haenzel statistic. Results Of 5400 procedures, 731 (13·5%) were in anaemic patients. These were older and had more comorbidity than non‐anaemic patients. There were 17 (2·3%) and 79 (1·6%) new cancers in anaemic and non‐anaemic patients, respectively (OR: 1·38; 95% CI: 0·81–2·35, P = 0·228). After propensity matching of 661 anaemic and 1305 non‐anaemic patients, we found no association between preoperative anaemia and cancer (OR: 0·94; 95% CI: 0·51–1·73, P = 0·837) or with GI cancers specifically (OR: 0·80; 95% CI: 0·25‐2·56, P = 0·707). Conclusion Preoperative anaemia per se may not be related to being diagnosed with cancer 1 year after THA and TKA. The optimal criteria for preoperative referral of anaemic patients to gastroenterologist in elective THA and TKA need further investigation.