Symptomatic, radiographic knee OA linked to increased mortality risk
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Both symptomatic and radiographic knee osteoarthritis are associated with an increased risk for all-cause mortality, according to findings published in Arthritis Care & Research.
“Osteoarthritis (OA) is the most common joint disorder and a leading cause of disability,” Yuqing Zhang, DSc, of Massachusetts General Hospital and Harvard Medical School, told Healio Rheumatology. “In addition, several studies also found that knee or hip OA were associated with an increased risk of all-cause mortality. However, the mechanisms linking OA to mortality were not clearly understood. Such knowledge has an important clinical implication because it would guide us to develop a more efficient intervention program that specifically targets a particular mechanism for the outcome.”
To analyze the link between knee pain, as well as symptomatic and radiographic OA, and all-cause mortality, and to identify mediators in this relationship, Wang and colleagues studied participants in the Osteoarthritis Initiative (OAI). According to the researchers, the OAI is a multi-center, observational study of OA and its risk factors, with sites in Baltimore, Pittsburgh, Pawtucket, Rhode Island, and Columbus, Ohio.
Wang and colleague divided participants in four groups — symptomatic knee OA, knee pain only, radiographic knee OA only and neither radiographic knee OA nor knee pain. Symptomatic knee OA was defined as both radiographic knee OA and knee pain. Radiographic knee OA was defined as a Kellgren and Lawrence grade of 2 or greater. The researchers used a multivariable Coxproportional model to analyze the link between knee OA status to allcause mortality. In addition, they examined to what extent this link was mediated by disability, physical and mental component summary scores of quality of life and oral painrelief medications.
Among the 4,796 baseline participants, 297 did not have adequate data for assessment and were excluded from the analyses. Of the remaining participants, 1,387 had symptomatic knee OA, 856 had knee pain only, 1,117 had radiographic knee OA only and 1,139 had neither radiographic knee OA nor knee pain.
According to the researchers, 282 participants died during the 96-month follow-up period. Multivariableadjusted analysis determined that, compared with those with neither radiographic knee OA nor knee pain, patients with symptomatic knee OA (HR = 2.2; 95% CI, 1.6-3.1), knee pain only (HR = 0.9; 95% CI, 0.61.4) and radiographic knee OA only (HR = 2; 95% CI, 1.42.9) had an increased risk for all-cause mortality.
The researchers found indirect effects of symptomatic knee OA on mortality through disability (HR = 1.1; 95% CI, 1.01.4) and physician component summary scores of quality of life (HR = 1.2; 95% CI, 1.01.4).
“Both symptomatic knee OA and radiographic knee OA were associated with an increased risk of all-cause mortality,” Zhang said. “These findings underscore the importance of developing appropriate preventive and treatment strategies to reduce the risk of knee OA. The increased risk of all-cause mortality from symptomatic knee OA was mediated through disability and PCS of QoL, suggesting that more efforts should focus on improving function and QoL to reduce all-cause mortality among patients with symptomatic knee OA.” – by Jason Laday
Disclosure: The researchers report no relevant financial disclosures.
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Joseph E. Huffstutter, MD
The article by Wang and colleagues reinforces previous observations regarding increased mortality related to knee osteoarthritis, felt to be secondary to decreased physical function. After controlling for variables of smoking, NSAID therapy and comorbidities, the researchers found that OA patients with radiographic changes of the knee — whether symptomatic or not —had a higher mortality than patients with normal radiographs.
Today’s rheumatologists should recognize that their patients with radiographic knee OA have an illness that will shorten their lives. This study highlights the need for OA therapies that do more than simply relieve pain, but actually preserve joint space and are true disease-modifying agents.
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