Taking Statins After Primary Total Hip Arthroplasty May Substantially Lower Revision Risk
By Nancy Fowler Larson
Medscape Medical News
May 13, 2010 — Patients who take statins after primary total hip arthroplasty (THA) may greatly reduce the risk for revision surgery, according to a study published in the May issue of the Journal of Bone and Joint Surgery, American Volume.
The most common reasons for revision after THA — one of the most frequently performed orthopaedic surgical procedures — are aseptic loosening of prosthetic parts, infection, dislocation, and fracture. Statins are generally prescribed to lower cholesterol levels. However, recent experimental clinical studies have indicated that statins may also have anti-inflammatory and antioxidative properties and may be related to enhanced endothelial function. Evidence of these effects is growing.
"In some, but not all, observational studies, these potential beneficial effects of statins on bone health have been confirmed in terms of a decreased fracture risk and increased bone mineral density among statin users," write Theis Thillemann, MD, of the Departments of Orthopedics and Clinical Epidemiology at Aarhus University Hospital, Aarhus, Denmark, and colleagues. "Moreover, experimental studies have described positive effects of statins on conditions mimicking the course of aseptic loosening of orthopaedic implants."
The goal of the study was to examine the impact of statins on revision risks after primary THA. The investigators obtained data on 2349 subjects from the Danish Hip Arthroplasty Registry, in which all public and private clinics are required to enter information about each patient. Between 1996 and 2005, the primary subjects had a revision of a primary total hip replacement. A control group of 2349 other subjects underwent total hip replacement but no revision.
Positive Impact Stops After a Dozen Prescriptions
The results showed that 8.1% (n = 190) of the primary patients and 20.1% (n = 473) of the control group filled at least 1 statin prescription after the THA. Simvastatin accounted for 77% of the prescriptions, with atorvastatin, lovastatin, pravastatin, fluvastatin, cerivastatin, and rosuvastatin comprising the remainder.
Findings regarding the effect of statins on revision rates are as follows:
The underlying cohort of 57,581 THAs had a 10-year failure rate of 8.9% (95% confidence interval [CI], 8.4% - 9.4%).
In statin users, the reduced adjusted relative risk (RR) for revision at 10 years was 0.34 (95% CI, 0.28 - 0.41) vs those who did not fill a statin prescription.
The adjusted RR decreased in relationship to each additional statin prescription, except for patients who filled more than 12 statin prescriptions: 1 to 4 prescriptions in 3 months to 1 year of treatment produced an RR of 0.42 (95% CI, 0.30 - 0.59); 5 to 8 filled in 1 to 2 years of treatment, 0.34% (95% CI, 0.23 - 0.51); 9 to 12 filled in 2 to 3 years of treatment, 0.16% (95% CI, 0.09 - 0.30); and more than 12 filled in more than 3 years of treatment, 0.36 (95% CI, 0.26 - 0.50).
"The reduced revision risk was the result of a lower risk for revision due to deep infection, aseptic loosening of components, dislocation, periprosthetic fracture, and miscellaneous causes, whereas statin use was not associated with a risk of revision due to pain or implant failure," the study authors write. "The mechanism underlying the association between postoperative statin use and reduced revision risk is unclear."
Study Limitations
The researchers listed several limitations to the study:
Data were available only for prescriptions filled, not for actual medication use.
Numbers of revisions can be affected by factors other than need, including patient and surgeon willingness to undergo and perform further procedures.
The registry data may not be complete.
Statin users are reportedly more diligent about their health than nonusers, and their lifestyle habits such as exercising and limiting alcohol intake may have contributed to the results.
Editorial: "Rigorous Analysis"
In an accompanying editorial, Bassam Masri, MD, FRCSC, professor and head of the Department of Orthopaedics at the University of British Columbia, Vancouver, called the study a "rigorous analysis." Dr. Masri also noted that the study authors currently recommend against prescribing statins for patients undergoing hip replacement who do not require the drug for other reasons. He acknowledged the authors' belief that using statins to lower the risk for revision after THA should wait until the findings are replicated and the mechanisms are better understood.
"I would certainly agree with this conclusion," Dr. Masri said. "Nevertheless, the data in this study are very compelling and should stimulate researchers in other centers, particularly those with sophisticated and large-scale registries, to try to corroborate these findings."
The Danish Rheumatism Association, the Augustinus Foundation, and the Korning Foundation supported the study. The study authors and Dr. Masri have disclosed no relevant financial relationships.
