WHI cohort study suggests focusing on optimizing physical functioning before surgery

Lower levels of physical function (PF) before total knee arthroplasty (TKA) may help explain why black women have worse outcomes than white women following the procedure, recent data suggested.

“The disparity in post-TKA PF was associated with disparities in PF preoperatively,” wrote study first author Alyson Cavanaugh, DPT, PhD, of the Joint Doctoral Program in Public Health at San Diego State University and the University of California, San Diego, and colleagues, in JAMA Network Open. “Efforts to reduce the racial/ethnic gap in postoperative function should be aimed at maintaining functional mobility among black women with arthritis and at reducing delays to surgery once need arises.”

Previous studies found that racial and ethnic minorities experienced lower satisfaction, higher postoperative pain, more residual joint stiffness, and more diminished PF after joint arthroplasty, researchers noted. The current study aimed to compare full PF trajectories among racial and ethnic groups both before and after TKA.

“A longer duration of living with limited mobility could be associated with further deterioration in muscle strength, restrictions in joint range of motion, and altered pain pathways,” Cavanaugh and colleagues wrote. “Both the level of PF at the time of surgery and the duration of PF limitations may be important factors associated with functional outcomes after TKA.”

The prospective cohort study examined data from the Women’s Health Initiative, which from 1993-1998 enrolled 161,808 postmenopausal, community-dwelling women from around the United States for clinical trials and observational study. Participants completed the RAND 36-Item Health Survey (RAND-36) PF questionnaire at screening, at 1-year follow-up, and at the end of the study. In addition, 25% of participants completed surveys at 3, 6, and 9 years. Responses to 3 specific RAND-36 questions were analyzed to help home in on activity limitations prior to TKA: responses indicating “a little” or “a lot” of limitations to her ability to climb one flight of stairs, walk one block, or walk several blocks.

In total, the cohort comprises 9,528 white women (mean [SD] age at surgery 74.6 [5.5] years), 622 black women (mean [SD] age at surgery 73.1 [5.3] years), and 175 Hispanic women (mean [SD] age at surgery 73.1 [5.2] years).

After adjusting for age, PF scores for black women lagged significantly behind those of white women during the 10-year preoperative period (mean difference −5.8 [95% CI −8.0 to −3.6]). Hispanic patients fared slightly worse than white patients.

In the decade following TKA, black women again had significantly lower PF scores than white women. At the 1-year mark, mean PF scores for black women were 7.8 points lower than for white women (95% CI −10.8 to −4.9), constituting a substantial expansion of the preoperative gap.

“Several studies investigating the potential causes of racial/ethnic disparities in post-TKA outcomes have focused on minority groups’ disproportionately higher use of low-volume surgeons or institutions and higher rates of perioperative and postoperative complications, including the development of arthrofibrosis. Others have focused on racial/ethnic differences in rehabilitation pathways or postoperative care,” Cavanaugh and colleagues wrote. “Our findings, using a community-dwelling cohort, add important and novel information by illustrating the severity of activity limitations and PF impairment, which was present earlier and for a longer duration among black women.”

The study also contained a bit of encouraging news, with researchers calling attention to a statistical smoothing of these differences over the longer term (10-year post-TKA mean difference −3.3 [95% CI −7.1 to 0.4]). Authors attributed the pattern to the finding that black women, on average, experienced a more gradual PF decline compared with white women (race/ethnicity by time interaction P=.06). After adjusting for preoperative PF scores, PF scores post-TKA were attenuated (mean difference 1 year after TKA, −3.0 [95% CI −5.3 to −0.7]), with no statistically significant differences emerging during long-term follow-up.

“Although a gap in function persisted in short-term follow-up, even after adjustment for preoperative function, it is promising to recognize that mid-term and long-term outcomes were similar between race/ethnicity groups after accounting for differences in preoperative PF,” Cavanaugh and colleagues wrote.

Cavanaugh and colleagues identified several limitations in the study, chiefly that the study population was limited to women enrolled in Medicare, meaning the findings may not be generalizable to other populations.

The study team suggested a holistic approach to the problem, including lifestyle changes and better access to relevant services.

“Preserving mobility and preventing further functional decline among black women may ultimately need to include strategies such as weight management, promotion of physical activity, or targeted interventions aimed at functional mobility, such as physical therapy,” Cavanaugh and colleagues wrote. “Uptake of evidence-based treatments for arthritis may help slow declines in mobility due to painful joints. However, black adults with arthritis have been shown to be less likely to receive medical or pharmaceutical treatments for pain and are less likely to receive physical therapy services.”

In an accompanying editorial, Patricia Franklin, MD, MBA, MPH, Northwestern University Feinberg School of Medicine in Chicago, and colleagues, none of whom were affiliated with the study, said the data merited more detailed examination.

“Future studies should consider replicating these findings using longitudinal methods in a cohort of patients that includes a sufficient number of men, patients younger than 65 years, and patients of Hispanic ethnicity,” Franklin and colleagues wrote. “These studies should consider an in-depth analysis of how baseline comorbidities, severity of disease at presentation, and social determinants of health are associated with variation in racial/ethnic and sex outcomes after TKA.”

  1. Lower levels of physical function (PF) before total knee arthroplasty (TKA) may help explain why black women have worse outcomes than white women following the procedure.

  2. Be aware that this cohort study from the Women’s Health Initiative was conducted in a Medicare population and may not be generalizable to other populations.

Scott Harris, Contributing Writer, BreakingMED™

Franklin reported receiving financial support from Depuy Inc. No other source appearing in this study disclosed any relevant financial relationship with industry.

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