Recovering from metabolic syndrome (MetS) lowers the risk for major adverse cardiovascular events (MACE), according to results of a nationwide cohort study published November 25 in Annals of Internal Medicine.

Several investigations have associated MetS (central obesity, dyslipidemia, glucose intolerance, and hypertension) with increased risk of cardiovascular disease (including acute myocardial infarction, revascularization, and acute ischemic stroke). Studies have also shown that resolving MetS leads to lowered risk for MACE.

To add large-scale data to population-level data linking the two conditions, Sehoon Park, MD, and colleagues from Seoul National University College of Medicine analyzed data from 9,553,042 people who received national health screenings from 2009 to 2014. Results were recorded in the National Health Insurance Database of Korea.

During that time, 27,161,051 people received national health screenings. The study design excluded individuals who had a history of MACE at the time of screening. Participants had to have had at least three screenings during the examination period.

The researchers considered the participants in four groups that reflect MetS status: chronic (n = 1,486,485), newly diagnosed (n = 587,088), recovered (n = 538,806), and those who did not have the condition (n = 6,940,663). Then they assessed the risks for developing cardiovascular disease or stroke, parsed by MetS status. The investigators calculated incidence rate ratios with adjustments for previous metabolic variables, body mass index, comorbidity scores, and other factors.

The people who recovered from MetS (incidence rate, 4.55 per 1000 person-years) had a lower incidence rate ratio (risk) for MACE (adjusted incidence rate ratio [IRR], 0.85) than people who had chronic MetS (incidence rate 8.52 per 1000 person-years).

In addition, people who were diagnosed with MetS during the timeframe (incidence rate, 6.05 per 1000 person-years) had a significantly higher risk of developing MACE (adjusted IRR, 1.36) compared with people who continued to not have MetS (incidence rate, 1.92 per 1000 person-years).

Hypertension corresponded to the greatest difference in associated MACE risk.

The wider-lens view of the study provides new granularity and insight into the MetS/MACE connection.

The researchers say the finding that MACE risk was higher in the MetS recovery group than in the MetS-free group — even though both were equally free from MetS during follow-up — suggests the damage to the cardiovascular system requires time to resolve. The finding points to the clinical significance of identifying a MetS history, even in patients whose MetS has resolved.

The similarity of MACE risk among participants who developed MetS and people with chronic MetS suggests that when severity is similar, people with new-onset MetS may have a MACE risk similar to those with chronic MetS, the authors stress.

Repeat assessment of MetS in a general health screening, as opposed to considering single measurements, can be "a simple tool for evaluating MACE risk in a population," the researchers explain, adding, "Further trials with population-scale interventions to reduce the burden of MACE by preventing or reducing MetS are warranted to confirm the benefits of recovery from or prevention of MetS."

"These findings are generalizable to the US population, since the same components comprise the metabolic syndrome in the US as elsewhere," Romesh Khardori, MD, PhD, professor of medicine: endocrinology & metabolism at Eastern Virginia Medical School in Norfolk, told Medscape Medical News.

Morgana Mongraw-Chaffin, PhD, MPH, an assistant professor of epidemiology and prevention at the Wake Forest School of Medicine in Winston-Salem, North Carolina, agreed.

"The results are generally consistent with the evidence about metabolic syndrome and cardiovascular disease risk from US cohorts. The important difference is that the US population is already further along in the obesity epidemic than the South Korean population studied in this article and has a higher prevalence of metabolic syndrome and its components, including hypertension and diabetes," she told Medscape Medical News.

Mongraw-Chaffin cites further evidence of healthier South Koreans. "The authors state that 40% of those in the MetS-free group had no MetS components, while studies in the US are rarely able to investigate this group at all due to the low prevalence," she said.

Although the study strongly supports existing guidelines for treating MetS, with lifestyle recommendations to prevent additional cardiovascular disease risk factors, Mongraw-Chaffin said, "the implications of this study are even broader, speaking directly to the need for prevention strategies. If MACE risk remains higher even after MetS recovery, then the key to having the lowest MACE risk is primary prevention of metabolic syndrome."

Limitations of the study include the retrospective design, short follow-up time, applicability to one population, and noninclusion of self-reported lifestyle variables.

The researchers and commentators have disclosed no relevant financial relationships.

Ann Intern Med. Published online November 25, 2019. Abstract

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