Metabolic syndrome as a risk factor for total hip or knee replacement due to primary osteoarthritis: a prospective cohort study (the HUNT study and the Norwegian Arthroplasty Register)

Abstract

ObjectiveBiochemical changes associated with obesity may accelerate osteoarthritis beyond the effect of mechanical factors. This study investigated whether metabolic syndrome and its components (visceral obesity, hypertension, dyslipidemia and insulin resistance) were risk factors for subsequent total hip replacement (THR) or total knee replacement (TKR) due to primary osteoarthritis.DesignIn this prospective cohort study, data from the second survey of the Nord-Trøndelag Health Study 2 (HUNT2) were linked to the Norwegian Arthroplasty Register for identification of the outcome of THR or TKR. The analyses were stratified by age (<50, 50–69.9 and ≥70 years) and adjusted for gender, body mass index, smoking, physical activity and education.ResultsOf the 62,661 participants, 12,593 (20.1%) were identified as having metabolic syndrome, and we recorded 1,840 (2.9%) THRs and 1,111 (1.8%) TKRs during a mean follow-up time of 15.4 years. Cox regression analyses did not show any association between full metabolic syndrome and THR or TKR, except in persons <50 years with metabolic syndrome who had a decreased risk of THR (hazard ratio [HR] 0.58, 95% CI 0.40–0.83). However, when including only participants whose exposure status did not change during follow-up, this protective association was no longer significant. Increased waist circumference was associated with increased risk of TKR in participants <50 years (HR 1.62, 95% CI 1.10–2.39) and 50–69.9 years (HR 1.43, 95% CI 1.14–1.80). Hypertension significantly increased the risk of TKR in participants <50 years (HR 1.38, 95% CI 1.05–1.81), and this risk was greater for men.ConclusionThis study found an increased risk of TKR in men <50 years with hypertension and persons <70 years with increased waist circumference. Apart from this, neither metabolic syndrome nor its components were associated with increased risk of THR or TKR due to primary osteoarthritis.

What Is the Evidence to Support the Association Between Metabolic Syndrome and Osteoarthritis? A Systematic Review

“…For hand OA, the data were limited and conflicting and were not sufficient to allow us to reach a definitive conclusion. Our systematic review showed that the strongest evidence came from a few longitudinal studies . More rigorous longitudinal evidence is needed.…”

“…For knee OA, 7 studies met our inclusion criteria, of which 2 were cross‐sectional , 1 was a case–control study , and 4 were cohort studies (Table ). Most of the reported effect estimates suggested a null association of MetS with knee OA after adjustment for BMI or weight . Despite meeting all of our selection criteria, the quality of the following studies and results needs to be interpreted with caution.…”

“…For hip OA, 3 studies were eligible, all of which were cohort studies (Table ). All studies had large sample sizes and a long duration of follow‐up.…”

“…Overall, we found methodologic deficiencies in most studies examining MetS and OA. Few studies used longitudinal data with sufficient sample sizes to assess associations between MetS and OA , and even fewer studies excluded prevalent OA cases, or prevalent joint replacement at baseline . The adequacy of control for confounding varied considerably across studies.…”

“…For studies using joint replacement as outcomes, excluding prevalent joint replacement at baseline is important. Hellevik et al excluded prevalent joint replacement at baseline and reported effect estimates for incident joint replacement. Future studies examining earlier stages of disease (possibly with magnetic resonance imaging) and joint pain are needed.…”