COPD/OSA phenotypes and inpatient outcome patterns among primary total hip arthroplasty hospitalizations: a national inpatient sample study, 2016–2022

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) are common among patients undergoing total hip arthroplasty (THA), but whether COPD-only, OSA-only, and coexisting COPD + OSA define distinct inpatient risk phenotypes remains unclear. This retrospective cohort study used the 2016–2022 National Inpatient Sample to identify adult primary THA hospitalizations. Hospitalizations were categorized as no COPD/no OSA, COPD only, OSA only, or COPD + OSA overlap. Outcomes included inpatient adverse outcomes, in-hospital mortality, prolonged length of stay (LOS), and high billed hospital charges. All analyses incorporated NIS discharge weights, sampling strata, and hospital clustering using SPSS Complex Samples procedures. Survey-weighted multivariable logistic regression estimated adjusted odds ratios (aORs), with no COPD/no OSA as the reference. Fracture-related indications and conversion arthroplasty were not separately excluded, which may contribute to residual heterogeneity in surgical indication. The unweighted cohort included 472,542 THA hospitalizations, representing an estimated 2,362,709 hospitalizations nationally after application of NIS discharge weights. Weighted estimates were 1,887,754 (79.9%) for no COPD/no OSA, 158,965 (6.7%) for COPD only, 274,325 (11.6%) for OSA only, and 41,665 (1.8%) for COPD + OSA overlap. COPD-only status was associated with prolonged LOS (aOR 1.44), high billed hospital charges (aOR 1.23), in-hospital mortality (aOR 2.02), mechanical ventilation (aOR 2.51), acute respiratory failure (aOR 4.63), pneumonia (aOR 2.83), acute renal failure (aOR 1.25), pulmonary embolism (aOR 1.79), transfusion (aOR 1.24), and periprosthetic mechanical complication (aOR 1.17). The overlap phenotype had the largest point estimate for acute respiratory failure relative to the no COPD/no OSA reference group (aOR 6.39) and was also associated with mechanical ventilation (aOR 2.92), prolonged LOS (aOR 1.46), and high billed hospital charges (aOR 1.15). OSA-only status showed a more selective pattern, including acute respiratory failure and rhythm-related outcomes, without increased odds of prolonged LOS.COPD/OSA phenotype status was associated with distinct inpatient outcome patterns among primary THA hospitalizations. COPD-related phenotypes showed elevated respiratory and resource-utilization burden, while OSA-only status showed a more selective pattern. These findings may help refine perioperative risk stratification but should be interpreted as associations rather than causal effects.