May 13, 2021/Orthopaedics/Research

Can the NarxCare Score Predict Adverse Outcomes in Total Hip Arthroplasty?

Study findings quantify risk for the first time, and what this means for managing care


Findings from a recent Cleveland Clinic-led study show for the first time that a higher NarxCare score (NCS) is associated with adverse outcomes following total hip arthroplasty (THA). Taking this one step further, findings also reveal a quantifiable threshold in NCS that stratifies risk for patients undergoing THA.


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The paper was published in Clinical Orthopaedics and Related Research.

A well-established, but not well-quantified link

The link between preoperative prescription drug use and adverse outcomes following THA has been well-established but lacks specificity when it comes to classifying risk.

Terminology falls short in capturing a multi-faceted picture of use. Preoperative classification such as “user” versus “non-user” or “chronic user” versus “non-chronic user” describes patterns, without recognizing dosage, duration, patterns, number of prescribers or number of pharmacies, all of which are important factors in defining and individualizing risk.

“We know there is more nuance and complexity to these binary categories,” says Nicolas Piuzzi, MD, senior author of the paper. The purpose of the study, he says, was to explore whether or not NCS could be repurposed to inform THA outcomes, and then use it as a data point to help guide clinical decision-making with patients.


NCS is a metric readily available in patients’ electronic health records. It reflects controlled drug-use patterns; higher scores reflect riskier-use patterns. The score continuously updates with each encounter, meaning that the score reflects changes in use patterns that reclassify risk for each episode of care.

Highest risk: Patients with an NCS greater than 300

The team led a retrospective review of 3,040 unilateral THA cases at Cleveland Clinic from November 2018 to December 2019. After controlling for potential confounding variables, the data show that patients with a preoperative NCS > 300 were more likely to experience 90-day readmission, procedure-related readmission, 90-day ED visits, length of stay > 2 days and non-home discharge compared with their counterparts with lower scores.

What does this mean for managing care? Dr. Piuzzi says that this association can alert physicians that a patient has a higher risk of complications, allowing them to anticipate and possibly prevent a negative occurrence.

He likens it to a hemoglobin A1c test for patients with diabetes. “Patients with diabetes used to have more postoperative complications than their non-diabetic counterparts,” he says. “But the use of HbA1c tests have helped to assess and inform care to minimize complications.”


For THA patients, NCS can provide a clinical road map of sorts, helping surgeons identify high-risk drug use patterns preoperatively and partner with patients to establish better prescription drug intake patterns to lower associated risks.

Beyond THA

The team recently evaluated the association between NCS levels preoperatively and adverse outcomes following total knee arthroplasty (TKA). This data is currently awaiting publication. They are also interested in exploring how a preoperative decrease in score may affect postoperative outcomes, potentially limiting complications.

“Ultimately, we hope this investigation and others of its kind can serve to inform and guide pre- and postoperative drug regimens and identify patients who may need additional support in their recovery,” Dr. Piuzzi concludes.

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