Association Between Change in Body Mass Index and Knee and Hip Replacements: A Survival Analysis of Seven to Ten Years Using Multicohort Data

Abstract

Objective To define the association between change in body mass index (BMI) and the risk of knee and hip replacement. Methods We used data from 3 independent cohort studies: the Osteoarthritis Initiative (OAI), the Multicenter Osteoarthritis Study (MOST), and the Cohort Hip and Cohort Knee (CHECK) study, which collected data from adults (45–79 years of age) with or at risk of clinically significant knee osteoarthritis. We conducted Cox proportional hazards regression analysis with clustering of both knees and hips per person to determine the association between change in BMI (our exposure of interest) and the incidence of primary knee and hip replacement over 7–10 years’ follow‐up. Change in BMI (in kg/m2) was calculated between baseline and the last follow‐up visit before knee or hip replacement, or for knees and hips that were not replaced, the last follow‐up visit. Results A total of 16,362 knees from 8,181 participants, and 16,406 hips from 8,203 participants, were eligible for inclusion in our knee and hip analyses, respectively. Change in BMI was positively associated with the risk of knee replacement (adjusted hazard ratio [HRadj] 1.03 [95% confidence interval (95% CI) 1.00–1.06]) but not hip replacement (HRadj 1.00 [95% CI 0.95–1.04]). The association between change in BMI and knee replacement was independent of participants’ BMI category at baseline (i.e., normal, overweight, or obese). Conclusion Public health strategies incorporating weight loss interventions could reduce the burden of knee but not hip replacement surgery.

Association of Change in Body Mass Index With Incidence and Progression of the Structural Defects of Hip Osteoarthritis: Data From the Osteoarthritis Initiative and the Cohort Hip and Cohort Knee study

“…None of these 3 studies found an association of weight loss with hip replacement overall. While the fifth study, which used the OAI cohort data (26), found an association of weight change (loss or gain) with risk of hip replacement in a subgroup of patients with hip pain at baseline over 8 years (hazard ratio 1.03 [95% CI 1.01-1.05]), this finding is in contrast with the findings from a large multicohort study (27) that did not find any evidence for association of weight loss or gain with risk of hip replacement in participants followed up over a duration of 7-10 years from 3 independent cohort studies: the OAI and the CHECK study, which we use in this current study, and the Multicenter Osteoarthritis Study (MOST). In sum, looking at the findings from these 6 previously published studies (22)(23)(24)(25)(26)(27) and the current study, it seems that weight loss is not beneficial for hip osteoarthritis.…”

Investigation of the association of weight loss with radiographic hip osteoarthritis in older community‐dwellingfemale adults

“…These findings add to growing evidence that weight loss has no benefit for hip osteoarthritis. We do not know of any randomized controlled trials that have investigated the effect of weight loss on hip osteoarthritis, but we know of 7 observational studies [16][17][18][19][20][21][22] that investigated the association of weight loss with hip osteoarthritis, in particular for structural defects of the hip joint, hip replacement, and hip pain. Of these 7 studies, 2 studies 18,22 found no evidence of an association between weight loss and structural defects of the overall hip nor defects in any individual structural features of the hip, and 4 studies [18][19][20][21] found no association with hip replacement (total and/or partial).…”

“…However, two of the 4 studies that investigated hip replacement 18,21 included the same OAI cohort in their analyses and did not find any evidence of an association between weight loss and the risk of hip replacement. Of the 7 studies [16][17][18][19][20][21][22] that investigated the association of weight loss with hip osteoarthritis, 3 studies [16][17][18] that investigated hip pain showed mixed results, with one 17 finding a reduction in self-reported hip pain after weight loss, but lacking a control group and a small sample size. None of these seven observational studies [16][17][18][19][20][21][22] specifically investigated the effect of weight loss on hip osteoarthritis in older adults, as they included adults aged between 18 and 79 years.…”

“…As the hip joint is less sensitive to obesity and weight change than the knee joint, 12,13 perhaps related to its ball-and-socket anatomy where mechanical forces are diffused across the joint in comparison to the hinge anatomy of the knee joint, [13][14][15] it may be the case that weight loss has no or little benefit for the hip. Indeed, observational studies [16][17][18][19][20][21][22] have not suggested any apparent benefit of weight loss for hip osteoarthritis.…”

“…None of the above-mentioned observational studies [16][17][18][19][20][21][22] specifically investigated the effect of weight loss on hip osteoarthritis in older adults, as they involved adults aged between 18 and 79 years. If weight loss has no clear benefit for hip osteoarthritis in older adults, guidelines recommending weight loss for this condition may introduce unnecessary health risks in older adults, for whom weight loss is associated with problems such as increased hip fracture, 23,24 mortality, 25 functional impairment, and incident disability.…”