Dual Diagnosis and Total Hip Arthroplasty.

The co-occurrence of a mental illness and a substance abuse disorder (SUD) is common and has been referred to as a "dual diagnosis" (DD). Although studies have independently investigated mental illness alone and SUD alone, few have examined the effects of these entities combined on complications. A search of the Medicare database from 2005 to 2012 identified 2000 DD patients who underwent total hip arthroplasty (THA). They were compared with 86,976 patients with mental illness only and 590,689 controls (no mental illness or SUD). Medical comorbidities and postoperative complications at 30-day, 90-day, and minimum 2-year time points were analyzed. There was a significant increase (P<.001) in 7 (53.8%) of 13 recorded postoperative medical complications, including acute renal failure (odds ratio [OR], 1.78), postoperative anemia (OR, 1.31), and blood transfusion (OR, 1.24), at the 90-day time point. In addition, there was a statistically significant increase overall in periprosthetic infection (periprosthetic joint infection OR, 4.30; P<.001), periprosthetic fracture (OR, 2.80; P<.001), dislocation (OR, 6.38; P<.001), and the need for THA revision (OR, 3.58; P<.001). When compared with patients with mental illness only, DD patients remained at significantly (P<.001) increased risk for 90-day and overall postoperative surgical complications, including dislocation, periprosthetic joint infection, and THA revision. Patients with a DD were at significant risk for perioperative complications compared with both control patients and patients with mental illness only. Studies investigating only psychiatric disease or only SUD may miss a vulnerable cohort. Further investigation is needed to exactly define to what extent DD amplifies complication rates. [Orthopedics. 2018; 41(3):e321-e327.].