Fibromyalgia is associated with increased 90-day readmission and procedural utilization during readmission after elective primary total hip arthroplasty.

PURPOSE: Fibromyalgia is a chronic pain syndrome characterized by central sensitization and frequent comorbidity clustering. Its impact on early readmission and procedural utilization during readmission after elective primary total hip arthroplasty (THA) remains incompletely defined. We evaluated the association between fibromyalgia and 90-day readmission and readmission-associated procedural outcomes after elective primary THA. METHODS: We performed a retrospective cohort study using the Nationwide Readmissions Database (NRD) (2020-2022). Elective primary THA hospitalizations were identified and restricted to procedures performed on hospital day 0. Fibromyalgia status was defined using ICD-10-CM diagnosis code M79.7 (captured in the database as diagnosis codes beginning with M797) during the index hospitalization. To improve comparability, we performed 1:5 propensity score matching without replacement. Outcomes included index hospitalization complications, all-cause 90-day readmission, and readmission-associated procedural outcomes, including component-level revision-type procedures, hip-related reoperation, and any inpatient procedure during readmission. RESULTS: Among 366,374 elective primary THA hospitalizations, 7,868 patients (2.1%) carried a diagnosis of fibromyalgia. After 1:5 propensity score matching, 46,126 patients remained (7,868 fibromyalgia; 38,258 controls), with standardized mean differences < 0.1 across matched covariates. During the index hospitalization, fibromyalgia was associated with higher rates of blood loss anemia (20.0% vs 16.5%; OR 1.27, 95% CI 1.19-1.35; p < 0.001), blood transfusion (3.5% vs 2.8%; OR 1.25, 95% CI 1.09-1.43; p = 0.001), pulmonary embolism (0.2% vs 0.1%; OR 2.21, 95% CI 1.20-4.08; p = 0.009), sepsis (0.2% vs 0.1%; OR 1.84, 95% CI 1.00-3.41; p = 0.048), and urinary tract infection (1.3% vs 1.1%; OR 1.25, 95% CI 1.01-1.55; p = 0.042). Ninety-day readmission occurred in 7.4% of patients with fibromyalgia compared with 5.0% of matched controls (OR 1.53, 95% CI 1.39-1.69; p < 0.001). During readmission, fibromyalgia was associated with increased odds of component-level revision-type procedures (1.6% vs 1.0%; OR 1.53, 95% CI 1.25-1.87; p < 0.001), hip-related reoperation (1.9% vs 1.4%; OR 1.37, 95% CI 1.14-1.65; p = 0.001), and any inpatient procedure (4.9% vs 3.4%; OR 1.48, 95% CI 1.32-1.67; p < 0.001). CONCLUSIONS: In a nationwide propensity-matched cohort of elective primary THA, fibromyalgia was associated with higher 90-day readmission and greater procedural utilization during readmission. Because important clinical variables and medication exposures are not captured in the NRD, these findings should be interpreted as associative rather than causal.