Adults aged 50 years or older with both abdominal obesity and vitamin D deficiency had more than twice the risk of death over 6 years compared with those without abdominal obesity and with sufficient vitamin D.
The investigators analyzed 5,520 participants from the English Longitudinal Study of Ageing (ELSA), a prospective study of community-dwelling adults in England. Wave 6, conducted in 2012 to 2013, served as baseline, when serum 25-hydroxyvitamin D [25(OH)D] concentrations were first collected. Mortality was tracked for 6 years using the UK National Health Service Mortality Registry.
Abdominal obesity was defined as waist circumference greater than 102 cm in men and greater than 88 cm in women. Researchers categorized 25(OH)D concentrations as sufficient, insufficient, or deficient and divided participants into six groups according to abdominal obesity and vitamin D status. Patients without abdominal obesity and with sufficient vitamin D served as the reference group. Cox regression models were used to assess mortality risk while accounting for sociodemographic, behavioral, and clinical characteristics.
During follow-up, 419 participants, or 8%, died. Patients with both abdominal obesity and vitamin D deficiency had the highest mortality risk, with a 123% higher risk of death compared with the reference group.
Higher mortality risk was also observed in patients who had only one of the two conditions or had vitamin D insufficiency. Among patients without abdominal obesity, vitamin D insufficiency was associated with a 91% higher risk of death, while vitamin D deficiency was associated with an 81% higher risk, compared with patients without abdominal obesity and with sufficient vitamin D.
Among patients with abdominal obesity, those with sufficient vitamin D had a 47% higher risk of death, while those with vitamin D insufficiency had a 50% higher risk, compared with the reference group. The researchers also tested whether the association between abdominal obesity, vitamin D status, and mortality differed by sex and found no statistically significant interaction.
The investigators noted that ELSA included only community-dwelling adults, limiting the generalizability of the findings to institutionalized populations. Abdominal fat was assessed using waist circumference rather than more precise body-composition methods, such as dual-energy x-ray absorptiometry or computed tomography. Participants excluded because of missing baseline data differed from those included, and ELSA did not collect potentially relevant biochemical measures, including serum parathyroid hormone concentrations.
Patients with both abdominal obesity and vitamin D deficiency also differed from the reference group across several baseline characteristics. They were older and had higher prevalences of hypertension, diabetes, heart disease, lung disease, stroke, osteoarthritis, and depressive symptoms, as well as lower grip strength and poorer memory performance. Although the models adjusted for numerous potential confounders, the observational findings do not establish causation.
Disclosures: The authors declared no conflicts of interest.
Source: Diabetes, Obesity and Metabolism
