Background/Purpose: Most data on the effect of comorbidities on primary total hip arthroplasty (THA) outcomes is focused on conditions that directly impact joint health, or on one underlying cause, such as osteoarthritis (OA), but there is little comparison between underlying causes of THA. This study aimed to assess the association of hypothyroidism with outcomes of primary THA, stratified by the primary underlying cause.

Methods: We identified all patients undergoing primary THA in the 2019 national inpatient sample. These patients were stratified based on primary diagnoses into hip OA (N=405691), avascular necrosis (AVN; N=17060), fracture (N=104265), inflammatory arthritis (IA; N=5720), and “other” (N=59155). We identified hypothyroidism and complications using secondary diagnoses. Complications codes were specified to be initial encounters, when possible. We performed multivariable-adjusted regression analyses adjusted for race, age, sex, hospital bed size, census region and teaching status with clinical and healthcare utilization outcomes as endpoints.

Results: Total cohort population was 591,891. Mean age was 68.8, mean length of stay (LOS) was 2.7 days, and 58.2% were female. Overall, hypothyroidism was significantly associated with increased LOS, non-routine discharge, acute renal failure (ARF), and anemia (p≤0.003 for each), and decreased risk of pneumonia (p=0.031). In the OA cohort, hypothyroidism was associated with increased LOS, non-routine discharge, anemia, and ARF (p≤0.008 for each). Hypothyroidism was associated with increased blood transfusion (p=0.049) in the AVN cohort. In the fracture cohort, hypothyroidism was associated with increased odds of non-routine discharge, and anemia (p≤0.020 for each), but decreased odds of deep veinous thrombosis (p=0.034).

Conclusion: Hypothyroidism was associated with clinical and healthcare utilization outcomes in a nationally representative sample of patients who underwent primary THA, especially in OA, AVN, and fracture cohorts. Interventions of tailored patient management strategies for hypothyroidism in THA peri-operative period should be tested for their efficacy to improve peri-operative outcomes.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/hypothyroidism-impacts-clinical-and-healthcare-utilization-outcomes-after-primary-total-hip-arthroplasty/