TOPLINE

Combining central obesity measures with BMI improved multimorbidity risk identification in adults with overweight; carrying both general excess weight and extra abdominal fat together carried the biggest health risk. Hypertension and malignant cancer emerged as the most common initial chronic conditions across adiposity categories.

METHODOLOGY

• Most multimorbidity research relies on BMI to measure obesity, but waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) provide insights into visceral and ectopic liver adiposity and are more effective in predicting disease risk or premature death, though their relevance to multimorbidity trends remains uncertain.
• Researchers analyzed data from 179,876 UK Biobank participants (from 2006 to 2010; mean age, approximately 55 years; 53% women) who had no long-term conditions at baseline and followed up with them for a mean of 9.9 years to assess incident first chronic condition and multimorbidity (at least two chronic conditions) risk.
• Obesity status was determined using BMI; central obesity was defined as WHR ≥ 0.90 for men and ≥ 0.85 for women or WHtR ≥ 0.50 for both sexes.
• Participants were classified into six mutually exclusive adiposity categories combining BMI with WHR and WHtR: normal BMI (18.5-24.9) with or without central obesity, overweight BMI (25.0-29.9) with or without central obesity, and obesity BMI (≥ 30.0) with or without central obesity.
• Subgroup analyses further classified participants with obesity BMI and central obesity into four groups based on obesity class: class I obesity (BMI 30.0-34.9) with or without high central obesity (WHtR ≥ 0.60 and/or WHR ≥ 1.0) and class II/III obesity (BMI ≥ 35.0) with or without high central obesity. Similarly, participants with overweight were categorized as those with or without high central obesity.

TAKEAWAY

• Hypertension was the most common first condition noted across all adiposity categories, increasing from 11.1% in those with normal BMI without central obesity to 26.0% in those with general obesity with central obesity, while malignant cancer was more prevalent in the lower-adiposity groups. These were also the most common second conditions, along with diabetes noted within the obesity categories.
• Participants with obesity BMI and central obesity demonstrated the highest risks for both first chronic condition (adjusted hazard ratio [aHR], 1.11; 95% CI, 1.087-1.138) and multimorbidity (aHR, 1.13; 95% CI, 1.093-1.172). Participants with overweight and central obesity also showed significantly elevated risks for both outcomes.
• Among individuals with overweight, those with high central obesity had significantly elevated risks compared with those without high central obesity for the both first condition (aHR, 1.06; 95% CI, 1.021-1.108) and multimorbidity (aHR, 1.15; 95% CI, 1.086-1.214). Among individuals with obesity, no clear differences were noted.
• Participants with normal BMI and central obesity did not show a significant difference in the risk for either the first condition or multimorbidity compared with those with normal BMI and no central obesity.

IN PRACTICE

“Incorporating a simple central obesity measure alongside BMI has the potential to improve early identification of at-risk individuals and more accurately capture the scale and distribution of multimorbidity risk,” the authors of the study wrote.

SOURCE

The study was led by Afua Ampadu-Yeboah, School of Health and Wellbeing, University of Glasgow, Glasgow, Scotland. It was published online in Clinical Obesity.

LIMITATIONS

Adiposity was measured only once at baseline, which might have led to exposure misclassification due to unmeasured weight changes over the follow-up period. The study population was restricted to disease-free UK Biobank participants, which reflected a healthy volunteer effect, potentially underestimating true population risks and limiting generalizability. The number of participants in the obesity without central obesity group was very small. Standard BMI and central adiposity thresholds derived primarily from White European populations might not be appropriate for all ethnic groups.

DISCLOSURES

No specific funding sources were reported in the study. One author disclosed consulting for and/or receiving speaker honoraria from various pharmaceutical, biopharmaceutical, and biotechnology companies and receiving grant support paid to his university by some companies outside the submitted work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.