medwireNews: People with obesity, particularly when diagnosed before the age of 50 years, are at very high risk for developing multiple comorbid conditions, say researchers.
Among 114,657 people from two Finnish cohorts, the 18.5% who were obese had a 5.39-fold increased risk for developing an additional condition during follow-up averaging 12.1 years, relative to people with a healthy weight (54.2% of the cohorts). They had an 8.65-fold increased risk for developing a third condition and a 13.22-fold increased risk for a fourth (complex multimorbidity).
Obesity was responsible for more than half of all cases of complex multimorbidity, with a population attributable fraction (PAF) of 55.2%, report Mika Kivimäki (University College London, UK) and co-researchers in The Lancet Diabetes & Endocrinology.
Within the obesity category, the risk increase for complex multimorbidity rose from 9.56-fold for class 1 obesity to 33.56-fold for class 3, but the PAF was highest for class 1 because of the larger number of cases, at a PAF of 34.9% compared with 5.7% for class 3.
Of note, the association with four or more multimorbid conditions was strongest in people who developed obesity before the age of 50 years, at a 22.11-fold increased risk compared with a 7.90-fold increase associated with obesity at an older age.
The researchers initially looked at 78 conditions and found obesity to be significantly associated with 28 of them at a hazard ratio of at least 1.50. They refined this to 21 conditions after excluding overlapping diagnoses. The most common diagnoses in people with multiple conditions were adult-onset diabetes, in 75.4%, followed by hypertension in 71.8%, and then sleep disorders, osteoarthritis, and arrhythmias, in 42.6%, 42.1%, and 34.4%, respectively.
All associations were replicated in a cohort of 499,357 individuals from the UK Biobank.
In a linked commentary, Avishai Tsur and Gilad Twig, both from Sheba Medical Center in Ramat Gan, Israel, say: “Strikingly, the proportion of individuals with complex multimorbidity by age 75 years among those with healthy weight was reached by age 55 years among those with obesity.”
And noting the only modest association between obesity and mortality risk (hazard ratio=1.32), they predict “a net accumulation of patients with complex multimorbidity […] in the future,” highlighting the urgent need to tackle obesity in the population.
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