BMI: ADVERSE EVENTS

Numerous studies have evaluated the association between patient weight ranges and adverse events following total hip arthroplasty (THA). The available data are of limited quality with considerable heterogeneity. However, it is not feasible to perform a randomized controlled trial since body mass index (BMI) is not easily modifiable. Therefore, it is unknown if, in the existing literature, patients with elevated BMI were otherwise medically optimized and if all potentially confounding factors were adequately controlled.

Most studies find either no significant difference or increased complications after THA when comparing overweight or obese subjects to normal weight individuals. With higher obesity classes, the current evidence seems to more clearly establishes an association with increased risk of postoperative complications. These medical adverse events include mortality, cardiac complications, acute renal failure, deep venous thrombosis, and allogeneic blood transfusion. Patients with elevated BMI are also at increased risk of surgical adverse events such as periprosthetic fracture, dislocation, periprosthetic joint infection/superficial infection/wound dehiscence, femoral component subsidence/loosening/revision, increased polyethylene wear, reoperation/revision for any reason, and increased intraoperative blood loss (Lung 2023, Bowditch 1999, Tohidi 2019, Mouchti 2018, Davis 2011, Bourget-Murray 2021, Peters 2020, Sayed-Noor 2019, Burn 2019). It is important to note that while the complication rates of postoperative adverse events are significantly higher in patients with elevated BMI, absolute rates of adverse events remain relatively low. The decision to proceed with THA in properly optimized patients with elevated BMI should remain at the discretion of the operating surgeon.

Benefits/Harms of Implementation
If elevated BMI is assumed to be a modifiable risk factor, there is value in identifying any association between BMI and adverse events after total hip arthroplasty (THA). While current evidence demonstrates an increased risk of postoperative adverse events in patients with elevated BMI, the quality of evidence is low. THA is a highly successful and cost-effective treatment that improves quality of life for patients with symptomatic hip arthritis. It is important that access to THA be preserved for medically optimized patients with elevated BMI. However, extremes of BMI are likely associated with a prohibitively high risk of postoperative adverse events.

Outcome Importance
Adverse events following THA can be catastrophic for both the patient and costly to the health care system.

Cost Effectiveness/Resource Utilization
THA has been demonstrated to be cost effective. Understanding the complication profile of patients with different BMIs may help surgeons make decisions on cost-effectiveness of THA in different patient populations.

Acceptability
It is accepted that BMI may increase the risk of adverse events following total joint arthroplasty.

Feasibility
It is feasible to determine pre-operative BMI and use this information to help risk stratify patients.

Future Research
Future prospective research should focus on how to properly select and optimize patients with elevated BMI to minimize the risk of postoperative adverse events. In addition, future research is needed to definitively determine if losing weight and lowering BMI reduces the risk of complications after THA. Further research into the varying ways weight loss strategies t is necessary to determine if certain strategies are more effective at reducing risks after THA than others.