Hip Replacement: 90-Day Mortality Halved in 8 Years

Jenni Laidman

September 27, 2013

The 90-day mortality rate associated with hip replacement fell by half in conjunction with the adoption of 4 clinical management strategies, according to a study of more than 400,000 cases in Wales and England, published in the September 28 issue of the Lancet.

Linda P. Hunt, PhD, research associate, Musculoskeletal Research Unit, School of Clinical Sciences, University of Bristol, United Kingdom, and colleagues analyzed data from the National Joint Registry for England and Wales, which was linked to a national mortality database and the Hospital Episode Statistics database.

Of 409,096 patients who underwent hip replacement for osteoarthritis between April 2003 and December 2011, the researchers identified 1743 deaths within 90 days of the surgery.

They found that 90-day mortality fell from 0.56% in 2003 (72 deaths/12,621 operations) to 0.29% in 2011 (164 deaths/60,727 surgeries). The relative risk halved during the study period after adjusting for age and sex, for a hazard ratio (HR) of 0.49 (95% confidence interval [CI], 0.37 - 0.65; P < .001) for 2011 relative to 2003.

Several clinical factors were associated with lower mortality after adjusting for sex, age group, and comorbidity. Those included a posterior surgical approach (HR 0.82; 95% CI, 0.73 - 0.92; P = .001); chemical thromboprophylaxis with heparin, with or without aspirin (HR 0.79; 95% CI, 0.66 - 0.93; P = .005); mechanical prophylaxis (HR, 0.85; 95% CI, 0.74 - 0.99; P = .036); and spinal vs general anesthetic (HR, 0.85; 95% CI, 0.74 - 0.97; P = .019).

In addition, the researchers found that the type of prosthesis showed no association with mortality and that being overweight was associated with reduced mortality (HR 0.76; 95% CI, 0.62 - 0.92; P = .006) for people with a body mass index of 26 to 30 kg/m2. However, the authors note, nearly 60% of body mass index data were missing, and the calculation assumes the data are missing at random.

"Widespread adoption of four simple clinical management strategies (posterior surgical approach, mechanical and chemical prophylaxis, and spinal anaesthesia) could, if causally related, reduce mortality further," the authors write.

Poor health was associated with a significantly increased risk for death, with moderate or severe liver disease associated with a nearly 10-fold greater risk for 90-day mortality adjusted for sex, age group, and comorbidity (HR, 9.70; 95% CI, 5.94 - 15.84; P < .0005). Metastatic cancer was associated with 7-fold increased mortality (HR, 7.19; 95% CI, 5.51 - 9.38; P < .0005), and myocardial infarction, congestive heart failure, and diabetes were all associated an increased hazard ratio for 90-day mortality between 2 and 3 times higher.

Kimona Issa, MD, from the Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Replacement, Sinai Hospital of Baltimore, Maryland, and the Department of Orthopaedic Surgery Seton Hall University, St. Joseph’s Regional Medical Center, Paterson, New Jersey, and Michael A. Mont, MD, from the Rubin Institute for Advanced Orthopedics, note in an accompanying comment that although the study authors propose the adoption of a posterior surgical approach, mechanical and chemical prophylaxis, and spinal anesthesia, they "were unable to evaluate other broader quality of life measures including patient-reported outcomes or other complications that might cause serious morbidity."

The authors and Dr. Issa have disclosed no relevant financial relationships. Dr. Mont receives royalties from Stryker and is a consultant for Janssen, Sage Products, Salient Surgical, Stryker, OCSI, and TissueGen, and receives institutional support from Stryker. He is also on the speakers bureau for Sage Products.

Lancet. 2013;382:1097-1076. Article abstract, Comment extract


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