Discordance Between BMI-Defined Overweight/Obesity and Waist-to-Height Ratio-Defined Central Obesity Among Adults with Type 2 Diabetes in Malawi: A Multicenter Cross-Sectional Study

Q: What are the key findings of this study?

Waist-to-height ratio identified central obesity in 80.1% of adults with type 2 diabetes vs 60.8% by BMI (kappa 0.35), with 23.7% having central obesity missed by BMI alone.

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Type 2 diabetes mellitus (T2DM) (n=1356). Intervention: Waist-to-height ratio (WHtR ≥ 0.50) central obesity classification vs. BMI-defined overweight/obesity (BMI ≥ 25 kg/m²). Primary outcome: Classification concordance and discordance between WHtR-defined central obesity (≥0.50) and BMI-defined overweight/obesity (≥25 kg/m²) (Cohen's kappa 0.35 (observed agreement 71.8%; central-obesity-only phenotype 23.7%), 95% CI 0.30-0.40).

Q: What does this research mean for the field?

Among adults with type 2 diabetes in Malawi, waist-to-height ratio identifies central obesity in 80.1% of individuals compared to 60.8% by BMI, with 23.7% having central obesity that is undetected by BMI alone. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.NEUTRAL.

Alexander Mboma; Elias Mwakilama; Alexander Kalimbira; Duc M; Tuyen Van Duong; Rong‐Hong Hsieh

doi:10.3390/diseases14090334

September 13, 2026DiseasesOpen Access

Discordance Between BMI-Defined Overweight/Obesity and Waist-to-Height Ratio-Defined Central Obesity Among Adults with Type 2 Diabetes in Malawi: A Multicenter Cross-Sectional Study

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Key result

Waist-to-height ratio detects central obesity in ~80% of type 2 diabetes, outperforming BMI.

Cohen's kappa 0.35 (observed agreement 71.8%; central-obesity-only phenotype 23.7%)
95% CI 0.30-0.40
n=1,356

Why the study?

BMI does not capture abdominal fat distribution and may classify adiposity differently from central-obesity indicators among adults with type 2 diabetes in Malawi.

Does waist-to-height ratio (WHtR) identify a substantial discordant burden of central obesity compared with BMI-defined overweight/obesity among adults with type 2 diabetes in Malawi?

Key Points

To quantify discordance between BMI-defined overweight/obesity and waist-to-height ratio (WHtR)-defined central obesity among adults with type 2 diabetes mellitus in Malawi.
Multicenter cross-sectional study of 1356 adults with clinician-confirmed type 2 diabetes attending diabetes clinics across three tertiary hospitals in Malawi.
Classified adiposity using BMI (≥ 25 kg/m2) and central obesity thresholds for waist circumference (WC ≥ 94/80 cm), waist-to-hip ratio (WHR ≥ 0.90/0.85), and WHtR (≥ 0.50).
Assessed agreement between BMI and WHtR using Cohen’s kappa and estimated associations using multivariable logistic and multinomial logistic regression models.
Prevalence was 60.8% for BMI-defined overweight/obesity, compared with 80.1% for WHtR, 67.5% for WC, and 65.3% for WHR central obesity.
Cross-classification revealed 71.8% observed agreement and a Cohen’s kappa of 0.35 (95% CI 0.30–0.40), with 23.7% having central obesity only and 56.3% having combined adiposity.
WHtR-defined central obesity was associated with ages 40–59 years (aOR 2.85, 95% CI 1.98–4.09), ages 60–85 years (aOR 3.07, 95% CI 2.11–4.47), female sex (aOR 2.77, 95% CI 2.08–3.68), ever-married status (aOR 2.12, 95% CI 1.31–3.43), and late-evening eating (aOR 1.36, 95% CI 1.02–1.80).

Study Design

Type

Cross-Sectional (n=1,356)

Multicenter

Yes

Structured PICO

Does waist-to-height ratio (WHtR) identify a substantial discordant burden of central obesity compared with BMI-defined overweight/obesity among adults with type 2 diabetes in Malawi?

P

Population

1,356 adults (mean age 52.8 years, 63.6% female) with clinician-confirmed type 2 diabetes mellitus for at least 6 months attending outpatient diabetes clinics at three tertiary hospitals in Malawi.

E

Exposure

Anthropometric assessment of central obesity using waist-to-height ratio (WHtR ≥ 0.50), waist circumference (WC ≥ 94 cm in men, ≥ 80 cm in women), and waist-to-hip ratio (WHR ≥ 0.90 in men, ≥ 0.85 in women)

C

Comparator

Conventional overweight/obesity classification using body mass index (BMI ≥ 25 kg/m²)

O

Outcome

Classification concordance and discordance between BMI-defined overweight/obesity (BMI ≥ 25 kg/m²) and WHtR-defined central obesity (WHtR ≥ 0.50), quantified by cross-classification into four mutually exclusive BMI-WHtR phenotypes, observed percentage agreement, and Cohen's kappasurrogate

Main Result

Effect estimate: Cohen's kappa 0.35 (observed agreement 71.8%; central-obesity-only phenotype 23.7%) (95% CI 0.30-0.40)

Absolute Event Rate: 80.1% vs 60.8%

Limitations

Cross-sectional design precludes causal inference regarding behavioral and psychosocial correlates of obesity
Facility-based recruitment from tertiary referral clinics may limit generalizability to primary care or community populations
Key behavioral measures (meal frequency, late-evening eating, physical activity, sedentary time) were self-reported and anthropometric measurements were taken once without intra- or inter-observer reliability estimates
No reference measure of body composition (e.g., DXA, MRI, bioelectrical impedance) was available to validate visceral or total adiposity
International anthropometric thresholds were applied rather than cut-offs derived and validated in Malawian adults
Small sample size in the 20 meals/week category (n=46) and evidence of lack of fit on the Hosmer-Lemeshow test (p=0.017) for the WHtR model
Facility-based recruitment from three urban tertiary referral hospitals limits generalizability to primary care or community settings
Self-reported behavioral measures (meal frequency, late-evening eating, physical activity, sedentary time) are subject to recall and social desirability bias, and single anthropometric measurements lacked formal reliability coefficients
Lack of reference body composition imaging (e.g., DXA, MRI, or bioelectrical impedance analysis)
Reliance on international anthropometric cut-offs not specifically validated in Malawian adults, and lack of adjustment for multiple comparisons or clustering in primary models

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Implication

Nearly one in four Malawian adults with type 2 diabetes has normal-weight central obesity (BMI <25 kg/m² with WHtR ≥0.50) that is missed by BMI screening alone, supporting routine incorporation of waist-to-height ratio into diabetes care.

Abstract

Background: Body mass index (BMI) does not capture abdominal fat distribution and may classify adiposity differently from central-obesity indicators. We quantified discordance between BMI-defined overweight/obesity and waist-to-height ratio (WHtR)-defined central obesity among adults with type 2 diabetes mellitus (T2DM) in Malawi. Methods: This multicenter cross-sectional study included 1356 adults attending diabetes clinics at three tertiary hospitals. Overweight/obesity was BMI ≥ 25 kg/m2. Central obesity was defined by waist circumference (WC ≥ 94/80 cm, men/women), waist-to-hip ratio (WHR ≥ 0.90/0.85), and WHtR ≥ 0.50. BMI and WHtR were cross-classified into four phenotypes, and agreement between the two classifications was summarized using observed agreement and Cohen’s kappa. Logistic and multinomial logistic regression models estimated (adjusted) odds ratios with 95% CIs; sensitivity analyses added study site as a fixed effect and modified Poisson models with robust variance provided adjusted prevalence ratios for the common binary outcomes. Results: Prevalence of BMI-defined overweight/obesity was 60.8%; central obesity was 67.5% (WC), 65.3% (WHR), and 80.1% (WHtR). Cross-classification showed 23.7% had central obesity only and 56.3% had combined overweight/obesity and central obesity; observed agreement between the two classifications was 71.8% and Cohen’s kappa was 0.35 (95% CI 0.30–0.40). Overweight/obesity was associated with older age (aOR 2.95), female sex (aOR 2.19), and physical inactivity (aOR 1.93). WC-defined central obesity was strongly associated with female sex (aOR 10.16), although the corresponding adjusted prevalence ratio was considerably smaller (aPR 2.25). WHR-defined central obesity was associated with older age, and anxiety. WHtR-defined central obesity was associated with older age, female sex, ever-married status, and late-evening eating behavior (aOR 1.36), although the association did not persist when study site was added. The combined phenotype was associated with age, sex, marital status, meal frequency, and physical inactivity. Conclusions: Overweight/obesity and central obesity were highly prevalent, with WHtR identifying the greatest burden and a substantial central-obesity-only phenotype that BMI alone would not detect. Incorporating WHtR alongside BMI may improve anthropometric assessment of adiposity in diabetes care, particularly among older and female patients.

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Cite This Study

Mboma et al. (2026) conducted a cross-sectional in Type 2 diabetes mellitus (T2DM) (n=1,356). Waist-to-height ratio (WHtR ≥ 0.50) central obesity classification vs. BMI-defined overweight/obesity (BMI ≥ 25 kg/m²) was evaluated on Classification concordance and discordance between WHtR-defined central obesity (≥0.50) and BMI-defined overweight/obesity (≥25 kg/m²) (Cohen's kappa 0.35 (observed agreement 71.8%; central-obesity-only phenotype 23.7%), 95% CI 0.30-0.40). Waist-to-height ratio identified central obesity in 80.1% of adults with type 2 diabetes vs 60.8% by BMI (kappa 0.35), with 23.7% having central obesity missed by BMI alone.

synapsesocial.com/papers/6aa9136e9013453be30a155a https://doi.org/10.3390/diseases14090334

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Discordance Between BMI-Defined Overweight/Obesity and Waist-to-Height Ratio-Defined Central Obesity Among Adults with Type 2 Diabetes in Malawi: A Multicenter Cross-Sectional Study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Discordance Between BMI-Defined Overweight/Obesity and Waist-to-Height Ratio-Defined Central Obesity Among Adults with Type 2 Diabetes in Malawi: A Multicenter Cross-Sectional Study

Key Points

Study Design

Structured PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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