In this retrospective study of two discrete ethnic populations, one Asian and one European, we investigated the demographic differences, as well as the differences in the prevalence of associated medical problems, among bariatric candidates. For this purpose, we utilized preoperative data gathered from patients who subsequently underwent MBS in two bariatric centers from India and from Greece that follow comparable perioperative protocols, in accordance with the IFSO® guidelines. Our principal findings suggest that there are significant differences between the two populations regarding most of the studied epidemiologic components and associated health issues.
The latest joint IFSO/ASMBS guideline acknowledge that the impact of obesity on Asian populations might be more severe as compared to Western ones and this has been reflected by the lower thresholds set to define obesity [6]. This is a very important first step with regard to inclusion of diverse bariatric populations. Studies like the one in hand are attempting to document such differences with the aim to assist in tailoring the management of obesity according to ethnic group.
The first observation is that there is a significant difference of approximately 5 years in the mean age of the two populations, with the Indian one being older on average. This might signify that patients seek surgical treatment of their obesity at a younger age in Greece, i.e., earlier in the timeline of disease, whereas this is not applicable for their Indian counterparts. Conversely, this age-related discrepancy might signify a different patient selection strategy on behalf of Greek healthcare providers, in the context of which older patients may be selected less frequently for MBS compared to their younger peers in view of the postulated suboptimal bariatric and metabolic outcomes and the increased perioperative morbidity that is often associated with surgery. However, it has been shown that age alone should not constitute a determining selection criterion for MBS [7]. Additionally, MBS seems to be equally effective across all age groups, although younger patients seem to respond more rapidly when it comes to improvement of their metabolic profile [8]. Most importantly, MBS has proven to be safe, even for patients of > 65 years of age [9], and even amidst health crises, as was the case with the Covid-19 pandemic [10].
The second observation is that there is a striking difference between the two populations regarding sex distribution, in the context of which almost 2/3 of the Greek cohort consisted of females, in contradistinction to a male preponderance in the Indian cohort. In other words, in the Greek cohort the allocation of bariatric surgery by sex followed the epidemiology of obesity itself, as it is known that the female gender is associated with twice the risk of being overweight or suffering from obesity than male [11]. Besides, it has been long known that the cardiovascular complications of obesity are more prevalent in men rather than women [12]. Applying this to our findings might imply that Indian individuals living with obesity are mostly operated with the indication of primary or secondary prevention of cardiovascular sequalae rather than (or simply for) losing weight. In any case, our observation adds to the existing evidence that gender disparities are a real phenomenon among people living with obesity, whereas ethnic differences might act synergistically to the increasing complexity of its management [11].
Regarding obesity-related medical problems, there was a significantly increased prevalence of T2DM, OSA, and DLP among Indian bariatric candidates compared to Greek ones. The prevalence of HTN was also higher in Indians, but this was non-significant. OSA featured the broadest difference between the two cohorts (45.1%), followed by T2DM (19.9%), and DLP (10.7%). This observation has two levels of interpretation. First, it confirms the notion that the burden of obesity and associated medical problems is more severe in Indian populations as compared to Western ones. This is also the rationale behind adopting lower BMI threshold for submitting these patients to MBS [6]. Besides, the prevalence of associated medical problems in bariatric candidates might be different from that in the general population of individuals living with obesity. For example, in a recent national study of 687,607 individuals with abdominal obesity from India, the prevalence of T2DM was 8.65% for males and 7.39% for females [13]. These numbers are far lower than those in our Indian cohort, where T2DM was prevalent in almost 1/3 of the bariatric candidates. This might be confirmatory of the conjecture that Indian patients who present for MBS do so at a more advanced stage of obesity, exactly because the consequences of obesity on metabolism have become overwhelming. In any case, these observations warrant further investigation with particular focus on directly comparing Indian and Western populations.
Our study has several limitations. First, its retrospective nature does not allow for the establishment of causal relationships for our findings. Second, although both centers abide by the perioperative guidelines of IFSO®, the occurrence of selection bias in the process of recruiting patients depending on discrepancies in infrastructures and locoregional administrative policies cannot be ruled out. Third, the considerable difference in the number of patients of the two cohorts is something that cannot be disregarded on statistical grounds. In this regard, the following figures need to be considered: at the time of the study, the Indian population measured about 1,500 million people, whereas the respective figure for the Greek population was approximately 10.5 million, i.e., almost 143 times less. Additionally, the percentage of adults living with obesity in India was 11%, versus 39% in Greece, according to World Obesity Atlas 2023 issued by the World Obesity Federation [14]. These figures create a pool of people who are candidates for MBS of approximately 165 million in India versus 4.1 million in Greece, i.e., 40 times less. On the contrary, the ratio between the two examined cohorts was 14.6, which is much less than the predicted discrepancy based on the aforementioned figures. Presumably, this reflects increased access to bariatric services in Greece, along with better ranking in global preparedness regarding the management of obesity, as it has also been acknowledged by the World Obesity Federation [14]. Consequently, given these massive demographic differences in order of magnitude, other confounding factors that could explain the disagreement in the sample sizes of the two cohorts (including popularity of MBS, insurance coverage, and patient volume of the two centers) are of secondary significance. A potential solution to this inherent issue would be the comparison of a bariatric population of the Indian subcontinent with its European or Mediterranean counterpart in the context of a larger scale, multicentric study. Finally, we need to acknowledge the fact that we focused on preoperative demographics and the prevalence of obesity-related health problems. Future research should further investigate the response of these associated medical problems following each type of MBS and compare these trends between different ethnic groups. Despite its limitations, to our knowledge it is among the first studies (if not the first) to directly address demographic and obesity-related medical problem discrepancies between an Indian and a European population.