Is American Joint Replacement Registry Data Representative of National Data? A Comparative Analysis

Area of Science:

• Orthopedic Surgery
• Arthroplasty Registries
• Health Services Research

Background:

• The American Academy of Orthopaedic Surgeons American Joint Replacement Registry (AJRR) is the largest US registry for total hip and knee arthroplasty (THA and TKA).
• The National (Nationwide) Inpatient Sample (NIS) provides a national benchmark for inpatient procedures.

Purpose of the Study:

• To evaluate the representativeness of AJRR data compared to national THA and TKA procedures in the NIS.
• To determine if AJRR findings can be generalized to the broader US patient population.

Main Methods:

• Comparative analysis of THA and TKA procedures from 2012-2018 (AJRR) and 2012-2016 (NIS).
• Calculation of Cohen d effect sizes to quantify differences in demographics, hospital volume, and geographic distribution.
• Inclusion of over 2.3 million primary THA and 3.4 million primary TKA procedures in the NIS, and 557,684 THA and 809,494 TKA procedures in the AJRR.

Main Results:

• Proportions of AJRR and NIS patients showed minimal differences in sex and age distributions (Cohen d ≤ 0.17).
• Small differences (Cohen d ≤ 0.34) were observed in hospital volume and geographic characteristics.
• AJRR demonstrated underrepresentation in Southern regions and low-volume hospitals, but overrepresentation in Northern and high-volume hospitals, mirroring overall trends.

Conclusions:

• Demographic, hospital volume, and geographic distributions are proportionally similar between AJRR and NIS databases.
• AJRR data is representative of the national experience, supporting the generalizability of its findings.
• The AJRR serves as a valuable and generalizable resource for understanding US hip and knee arthroplasty trends.