Comparison of Autonomic Indices in Normal Weight, Overweight and Obese Adults - a Comparative Analysis Using South East Asian Criteria for Obesity Classification.

Objectives: Autonomic function assessment, performed using heart rate variability and Ewing's battery, can help unravel autonomic neuropathy in many clinical disorders. This assessment can be affected by obesity. We revisited the relationship between autonomic function parameters and obesity. The body mass index (BMI) based stratification based on standard World Health Organization (WHO) classification and revised South East Asian (SEA) classification was employed.

Materials and methods: Apparently, healthy subjects of either sex were included in the present study. Subjects were classified into normal weight (NOR), overweight (OW) and obese (OB) categories using both guidelines. An autonomic function test was performed, documenting heart rate variability (HRV) and Ewing's battery of tests including postural challenge, deep breathing, cold pressor and isometric exercise. Parameters were compared between the three groups.

Results: We recruited 105 healthy subjects (89 males, 16 females) with a mean age of 29.83 ± 5.44 years. There were 33, 29 and 43 subjects in the NOR, OW and OB categories, respectively, as per the revised SEA classification. Similarly, 63 subjects were NOR, 42 OW, and six OB, as per the WHO criteria. There was no significant difference between HRV parameters and autonomic reactivity parameters between NOR, OW and OB subjects as per the revised SEA and WHO criteria.

Conclusions: The WHO criteria underestimated obesity in our population sample. In addition, there was no significant difference in autonomic parameters between NW, OW and OB subjects as per the SEA criteria. We propose that the effect of obesity on autonomic parameters may require a revisit in light of revised BMI criteria for the SEA population.