Male Smokers at Decreased Risk for Joint Replacement Surgery

According to recent research, men who smoke are at a decreased risk of receiving total joint replacement (TJR) surgery of the hip or knee compared to men who have never smoked.

"Our study is the first to demonstrate a strong inverse correlation between smoking duration and risk of total joint replacement," said lead author George Mnatzaganian, PhD, from the University of Adelaide in Adelaide, Australia.

“The independent inverse associations of smoking with risk of total joint replacement were evident also after adjusting for major confounders and after accounting for the competing mortality risk in this elderly cohort of men,” continued Mnatzaganian.

Based on data from the National Hospital Discharge Survey, in the year 2007, roughly 230,000 people in the United States underwent hip arthroplasty, while 543,000 had knee arthroplasty. The most frequent cause for arthroplasty is severe osteoarthritis (OA), which is connected to known risk factors such as older age, the female sex, and obesity.

The researchers studied data that was collected during the Health in Men Study (HIMS), which was based on a population-based randomized trial of screening for abdominal aortic aneurysms between 1996 and 1999; the study was conducted on 11,388 Australian men over the age of sixty-five. The researchers of this current study focused on clinical data, hospital morbidity data, and mortality records of HIMS in order to assess the connection between smoking, body weight, and physical activity with the risk of undergoing TJR.

The researchers found that, of the 857 participants who had joint replacement surgery, 59.5% underwent total knee replacement and 40.5% had total hip replacement.

Smoking was found to reduce the risk of undergoing TJR through the use of Cox proportional hazards regressions and competing risk regressions models, which become apparent after twenty-three years of smoking. Males who had smoked for more than forty-eight years were found to be 42% to 51% less likely to undergo TJR than males who had never smoked before.

The investigators also discovered that vigorous exercise increased the risk of a man undergoing TJR, but the connecting reached statistical significance only in the age-group of seventy to seventy-four year old men (adjusted-hazard ratio: 1.64, 95% CI: 1.19 - 2.24). The authors reported that adjusting the data for Deyo-Charlson Index or Elixhauser's co-morbidities did not alter or eradicate these findings.

The research was not without limitations; the study failed to directly determine OA status, account for alterations in patient characteristics over time, and was of an observational design, which excluded determination of a causal relationship between smoking and OA.

“Further investigation is needed to determine how smoking impacts the development of [osteoarthritis],” acknowledged Mnatzaganian.

"More research is needed to better understand the role of smoking in the pathogenesis of OA,” the authors wrote, “but also into the selection pathways for patients for whom TJR is indicated. Notwithstanding the findings, this study reinforces the overwhelming excess risk of premature mortality associated with smoking."

This study is published online in the journal Arthritis & Rheumatism.