Factors Associated With 30-Day Readmission After Primary Total Hip Arthroplasty
Authors: Adam M. Ali, Mark D. Loeffler, Paul Aylin, Alex Bottle
Journal: JAMA Surgery (2017)

<h3>Importance</h3> Thirty-day readmission to hospital after total hip arthroplasty (THA) has significant direct costs and is used as a marker of hospital performance. All-cause readmission is the only metric in current use, and risk factors for surgical readmission and those resulting in return to theater (RTT) are poorly understood. <h3>Objective</h3> To determine whether patient-related predictors of all-cause, surgical, and RTT readmission after THA differ and which predictors are most significant. <h3>Design, Setting, and Participants</h3> Analysis of all primary THAs recorded in the National Health Service (NHS) Hospital Episode Statistics database from 2006 to 2015. The effect of patient-related factors on 30-day readmission risk was evaluated by multilevel logistic regression analysis. The analysis comprised all acute NHS hospitals in England and all patients receiving primary THA. <h3>Main Outcomes and Measures</h3> Thirty-day readmission rate for all-cause, surgical (defined using<i>International Statistical Classification of Diseases and Related Health Problems, Tenth Revision </i>primary admission diagnoses), and readmissions resulting in RTT. <h3>Results</h3> Across all hospitals, 514 455 procedures were recorded. Seventy-nine percent of patients were older than 60 years, 40.3% were men, and 59.7% were women. There were 30 489 all-cause readmissions (5.9%), 16 499 surgical readmissions (3.2%), and 4286 RTT readmissions (0.8%); 54.1% of readmissions were for surgical causes. Comorbidities with the highest odds ratios (ORs) of RTT included those likely to affect patient behavior: drug abuse (OR, 2.22; 95% CI, 1.34-3.67;<i>P</i> = .002), psychoses (OR, 1.83; 95% CI, 1.16-2.87;<i>P</i> = .009), dementia (OR, 1.57; 95% CI, 1.11-2.22;<i>P</i> = .01), and depression (OR, 1.52; 95% CI, 1.31-1.76;<i>P</i> &lt; .001). Obesity had a strong independent association with RTT (OR, 1.46; 95% CI, 4.45-6.43;<i>P</i> &lt; .001), with one of the highest population attributable fractions of the comorbidities (3.4%). Return to theater in the index episode was associated with a significantly increased risk of RTT readmission (OR, 5.35; 95% CI, 4.45-6.43;<i>P</i> &lt; .001). Emergency readmission to the hospital in the preceding 12 months increased the risk of readmission significantly, with the association being most pronounced for all-cause readmission (for &gt;2 emergency readmissions, OR, 2.33; 95% CI, 2.11-2.57;<i>P</i> &lt; .001). Hip resurfacing was associated with a lower risk of RTT when compared with cemented implants (OR, 0.69; 95% CI, 0.54-0.88;<i>P</i> = .002) but for other types of readmission, implant type had no significant association with readmission risk. Increasing age and length of stay were strongly associated with all-cause readmission. <h3>Conclusions and Relevance</h3> Many patient-related risk factors for surgical and RTT readmission differ from those for all-cause readmission despite the latter being the only measure in widespread use. Clinicians and policy makers should consider these alternative readmission metrics in strategies for risk reduction and cost savings.