A Single Center Prospective Observational Cohort Study on the Association of Asia Pacific Classification of Body Mass Index, Waist Circumference, Waist Hip Ratio with COVID-19 Outcomes and Severity in a Philippine Tertiary Hospital

Khia Anne Patricia S Quiwa^1,2*, Kathryn Gayle S Quiwa², Hannah Angelica P Lacar², Aries Bjorn C Garingalao², Elizabeth Paz- Pacheco^1,2

¹Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, The Medical City, Philippines
²Department of Internal Medicine, The Medical City, Philippines

*Correspondence author: Khia Anne Patricia S Quiwa, Section of Endocrinology, Diabetes and Metabolism, Department of Medicine, The Medical City, Philippines and Department of Internal Medicine, The Medical City, Philippines;
Email: [email protected]

Citation: Quiwa KAPS, et al. A Single Center Prospective Observational Cohort Study on the Association of Asia Pacific Classification of Body Mass Index, Waist Circumference, Waist Hip Ratio with COVID-19 Outcomes and Severity in a Philippine Tertiary Hospital. Jour Clin Med Res. 2025;6(1):1-16.

Copyright^© 2025 by Quiwa KAPS, et al. All rights reserved. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Table 2: Clinical outcomes in moderate COVID-19, by BMI class (n=167).

Among patients with severe COVID-19, there was insufficient evidence to support significant variations in distributions of outcomes of interest across Asia-Pacific BMI groups (Table 3).

Table 3: Clinical outcomes in severe COVID-19, by BMI class (n=15).

Univariate and Multivariate Analyses

Respiratory Decompensation

On univariable analysis, obesity and waist circumference were significantly associated with the odds of respiratory decompensation. However, this association was not sustained upon adjustment for comorbidities, smoking, COVID-19 vaccination history, day of illness on admission and use of investigational drugs (Table 4).

Table 4: Association of visceral adiposity indicators with respiratory decompensation.

ICU Admission

On univariable analysis, waist and hip circumferences were both significantly associated with the odds of ICU admission. After controlling for potential confounders, only hip circumference retained significant association, with odds for the outcome increased by 5% (95% CI 1-10%) with every additional centimeter in hip circumference (Table 5).

Table 5: Association of visceral adiposity indicators with ICU admission.

Mortality

BMI, waist circumference, hip circumference or WHR were not found to be significantly associated COVID-19 mortality, whether on univariable nor multivariable analysis (Table 6).

Mortality

BMI, waist circumference, hip circumference or WHR were not found to be significantly associated COVID-19 mortality, whether on univariable nor multivariable analysis (Table 6).

Table 6: Association of visceral adiposity indicators with mortality.

Discussion

This is the first prospective observational cohort to investigate the influence of Asia-Pacific classification of Body Mass Index and visceral adiposity assessed by waist circumference and waist hip ratio on COVID-19 outcomes. According to the Asia Pacific classification, BMI is classified into four groups: underweight (<18.5 kg/m²), normal weight (18.5-22.9 kg/m²), overweight (23-24.9 kg/m²) and obese (> 25 kg/m²).

In our study involving 182 adult patients hospitalized with COVID-19, 127 or 70% of the patients were obese (BMI >25 kg/m²) by Asia-Pacific BMI classification. The mean waist circumference, hip circumference and waist-hip ratio were 101.75 ± 14.27 cm, 102.65 ± 13.06 cm and 0.99 ± 0.07, respectively. This proportion is consistent with a Philippine-based retrospective cohort study in 2017 examining the individual features of metabolic syndrome among 1367 subjects in a Philippine tertiary hospital [11]. In this study, 66.2% of the patients were obese and the mean BMI was 28.2 kg/m² [11]. The mean waist circumference was documented at 96.8 cm [11].

Of the 182 patients, 167 presented with moderate COVID-19 and 15 patients had severe COVID-19. The incidence of severe COVID-19 infection in middle-aged patients was similar to that in older populations, which meant that the attributable risk may be similar in both groups. Our study findings show that in the obese group, most were male. There were no deaths recorded in the underweight group, although there were only two patients in this group. The mortality rate was lowest among those with normal BMI (7.69%).

On univariable analysis, waist and hip circumferences were both significantly associated with the odds of ICU admission. However, upon controlling for potential confounders, only hip circumference retained significant association with ICU admission. In particular, for every additional centimeter increase in hip circumference, the odds for the outcome of ICU admission increased by 5% (95% CI, p-value <0.05). In contrast, an observational study done in Ukraine determining mortality risks in 367 in-patients with COVID-19 found that only waist circumference (>105 centimeters) is an independent risk factor for severe COVID-19 outcomes particularly mortality [12]. Our hospital cohort of COVID-19 patients found no significant association between waist circumference and respiratory decompensation and mortality. To date, there are no studies showing the association of hip circumference alone with respiratory decompensation and mortality from COVID-19. While waist-hip ratio is based on the values of waist circumference and hip circumference, it provides a different measurement and perhaps may not always follow the trend of hip and waist circumference. For instance, a higher hip or waist circumference might not always indicate a higher waist-hip ratio.

Furthermore, our study found that BMI, waist circumference, hip circumference or waist-hip ratio were not found to be significantly associated COVID-19 mortality, whether on univariable or multivariable analysis. Several studies have investigated the association between COVID-19 and obesity, body mass index, waist circumference and waist-hip ratio, yet the mechanistic associations in Asians and in Filipinos remain unclear. Respiratory decompensation and sepsis were more frequently seen in obese patients (BMI > 25 kg/m²) than in the other three BMI classes. A possible explanation for the increased risk of developing respiratory decompensation and mortality among patients with higher BMI include difficulties in lung expansion, difficulties in ventilation and proning, which may complicate recovery time [13]. However, adjusting for confounders attenuated the significance of the association.

Furthermore, our study found that BMI, waist circumference, hip circumference or waist-hip ratio were not found to be significantly associated COVID-19 mortality, whether on univariable or multivariable analysis. Several studies have investigated the association between COVID-19 and obesity, body mass index, waist circumference and waist-hip ratio, yet the mechanistic associations in Asians and in Filipinos remain unclear. Respiratory decompensation and sepsis were more frequently seen in obese patients (BMI > 25 kg/m²) than in the other three BMI classes. A possible explanation for the increased risk of developing respiratory decompensation and mortality among patients with higher BMI include difficulties in lung expansion, difficulties in ventilation and proning, which may complicate recovery time [13]. However, adjusting for confounders attenuated the significance of the association.

In our study, we stratified our analysis of COVID-19 outcomes with measures of visceral adiposity since previous studies conclude that obesity and increased waist circumference are associated with severe COVID-19 outcomes and overall mortality [1,2,5,14]. Our study dealt with a smaller sample population compared to the earlier studies hence the possibility of selection bias due to the inclusion criteria. There were also significantly more obese patients (70% of the study population) and more moderate than severe COVID-19 patients (91.75% or 167 patients, vs 8.25% or 15 patients) which proved investigating significant differences between the two groups and their COVID-19 outcomes across the BMI classifications to be challenging. The associations were difficult to establish due to the uneven distribution of the subjects in each category, specifically because there were more patients analyzed in the moderate group versus severe and majority of the patients were obese. Thus, the interpretation of results should be viewed carefully. These factors may account for the association not retaining its significance upon adjustment for comorbidities, smoking, COVID-19 vaccination history, day of illness on admission and use of investigational drugs such as remdesivir and tocilizumab.

Our study attempted to examine the risk associated with unit increases in Asia Pacific classification of Body Mass Index, however we found that in patients afflicted with moderate and severe COVID-19, there were no significant variations in distributions of outcomes of interest (respiratory decompensation, sepsis, septic shock and mortality) across Asia-Pacific BMI groups. A large population-based study, of which a large population had a BMI lower than 30 kg/m², found that having a Body Mass Index (BMI) of 30 kg/m² or higher was associated with a slightly greater risk of death from COVID-19 than a BMI of less than 30 kg/m² [2]. A community-based prospective cohort study found a significant positive linear association between increasing BMI and admission to hospital and to ICU due to COVID-19, with significantly higher risk for every BMI unit increase, with each unit increase in BMI above 23 kg/m² associated with increased risk of hospital admission and death due to COVID-19 particularly among people aged 20-39 years [1]. In another study, they found that risks for hospitalization, ICU admission and death were lowest among patients with BMIs of 24.2 kg/m², 25.9 kg/m² and 23.7 kg/m², respectively and that the risk increased with increasing body mass index [4]. A plausible explanation for not finding a significant interaction between COVID-19 outcomes and BMI groups in our study is that a large proportion (70%) of the study population are obese or have a BMI higher than 25 kg/m².

Limitations

Due to the nature of the study and the inclusion criteria, the study population was limited to patients who belonged in the WHO severity scales 4, 5 and 6 and this population may not be representative of severity of risk in the general population. Another limitation of our study was that we did not include prevalence rates of individual features of metabolic syndrome, such as elevated triglyceride levels, low high density lipoprotein levels, elevated fasting blood sugar and incidence of diabetes and hypertension in the assessment and these may be valuable to include in larger studies to further characterize the risk profile of Filipinos. Furthermore, the level of control of co-morbidities of the study population was not analyzed, which would account as an important confounder. There was bias in measurement of the waist-hip circumference, since the patients are supposed to be measured in an upright position. Therefore, patients who were unable to stand at admission due to dyspnea or respiratory distress had to be excluded from analysis, hence introducing selection bias. Due to the number of patients to whom this applied (39 out of 221), the influence on the results may be substantial. The limitations may also be explained by difficulty in completing parameters during the pandemic in the local setting. Our final limitation is that our data collection was done during the height of the COVID-19 surge involving the Delta variant and the results may not be representative of the patients afflicted by the other variants such as the Omicron variant.

Conclusion

Our findings from this single center prospective cohort emphasize that although the COVID-19 mortality rate was lowest among those with normal BMI (7.69%), progression severity and respiratory decompensation were not significantly associated with obesity as defined by the Asia Pacific BMI classification. This finding warrants confirmation in future studies with a representative sample size in each Asia pacific body mass index category. Further evaluation with larger prospective cohorts would prove to be useful, since body mass index is an important modifiable risk factor that may guide national health policy creation in terms of prioritization of populations for risk reduction and vaccination against COVID-19 infection. Although still unproven, interventions that reduce weight and visceral adiposity (waist circumference, waist-hip ratio) may reduce the risk of severe COVID-19 outcomes in Filipinos.

Clinical pearls for endocrinologists and clinicians should include the information that a non-invasive measurement of height, weight, waist and hip circumference on patients afflicted with COVID-19 may help in the acquisition of more robust data sets which may help shed light on further implications of the Asia Pacific classification of body mass index and measures of visceral adiposity on the outcomes of COVID-19 infection in Filipinos.

Consent for Publication

The authors declare that there is no conflict of interest regarding the publication of this paper.

Funding

The author(s) received no funding for this work.

Authors’ Contributions

All authors contributed to the writing of the manuscript.

Acknowledgement

Not applicable.

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Supplemental Tables

Table 1: Comorbidities and presenting symptoms by BMI class.

Table 2: Clinical outcomes by BMI class.

Table 3: Clinical outcomes in unvaccinated COVID-19 patients by BMI class (n=93).

Table 4: Clinical outcomes in partially vaccinated COVID-19 patients by BMI class (n=18).

Table 5: Clinical outcomes in fully vaccinated COVID-19 patients by BMI class (n=71).