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BMI and KOSC scores

BMI and KOSC scores key to patient’s treatment choice

Patients with a BMI≥40 had 85% increased odds of choosing bariatric surgery, whereas physical inactivity was associated with 29% increased odds of bariatric surgery (reference lifestyle intervention)

BMI has been reported to be the strongest of King’s Obesity Staging Criteria (KOSC) -domain associated with the choice of subsequent bariatric surgery after a shared decision making process, according to researchers from Norway and the UK. The paper, ‘The association between severity of King’s Obesity Staging Criteria scores and treatment choice in patients with morbid obesity: a retrospective cohort study’, published in BMC Obesity,

KOSC comprises of a four-graded set of health-related domains and the researchers examined whether, according to KOSC, patients undergoing bariatric surgery differed from those opting for conservative treatment. They hypothesised that patients who underwent bariatric surgery would have higher scores according to KOSC in most domains, indicating more obesity related co-morbidities.

In total, 2,142 treatment seeking patients eligible for bariatric surgery were included in the final analysis (n=2,075; 98% were Caucasians). A total of 157 (7%) study participants treated with lifestyle intervention first and bariatric surgery thereafter were included in the lifestyle intervention group. The overall median (range) time from the first consultation until surgery was 21 (380) months.

The wait time for surgery in the subgroup of patients who chose lifestyle intervention first and then bariatric surgery was longer than for patients who chose bariatric surgery first (median 37 [11–80] months vs. 19 [3–78] months, p<0.001). Treatment of morbid obesity is financed through the universal health care system in Norway, so the patients were able to choose between intensive lifestyle intervention and bariatric surgery independent of their financial status.

Some 1,329 (62%) patients chose lifestyle intervention and 813 (38%) opted for bariatric surgery. Compared to those who underwent lifestyle intervention, the patients treated with bariatric surgery were approximately two years younger, had a higher BMI, had a higher proportion of current smokers as well as a lower ten-year estimated risk of incident cardiovascular disease (CVD). The proportions of patients with obstructive sleep apnoea (OSA), type 2 diabetes, hypertension, coronary artery disease and MetS did not differ significantly between groups. Patients who developed obesity before 20 years of age were more likely to choose bariatric surgery first than the patients who developed obesity as adults (i.e. ≥20 years of age) (65% vs. 55%, p<0.001).

Patients with a BMI≥40 had 85% increased odds of choosing bariatric surgery (Figure 1), whereas physical inactivity was associated with 29% increased odds of bariatric surgery (reference lifestyle intervention). In addition, patients with ≥20% risk of CVD had 32% lower odds of bariatric surgery than those with < 20% risk of CVD.

Figure 1: The figure shows univariable analysis for obesity treatment by each domain of King’s obesity staging criteria (KOSC)

Among patients with ≥20% increased CV-risk, the 105 patients treated with bariatric surgery were on average four years younger than the 241 patients treated with intensive lifestyle intervention (age 54 [6] vs. 58 [7] years, p<0.001, respectively). After adjustments for age and gender, only higher stages of BMI remained significantly associated with subsequent bariatric surgery (OR 1.81 [95% CI 1.46, 2.27]).

After stratification by gender, having a BMI≥40 was associated with higher odds of subsequent bariatric surgery than BMI<40 in both women and men (OR [95% CI] 1.77 [1.37, 2.30] and 2.07 [1.38, 3.13]). Conversely, compared with being physically active for a minimum of one hour each week, being physically inactive was associated with subsequent bariatric surgery in women, but not in men (1.36 [1.05, 1.78] and 1.12 [0.76, 1.65]).

Compared with patients with minor health risk in the BMI domain (Domain B, stage 1), patients within both stage 2 and stage 3 were more likely to undergo bariatric surgery (stage 2: 1.71 [1.37, 2.15] and stage 3: 3.22 [1.73, 3.14], respectively). In the diabetes domain (Domain D), conversely, patients within stage 2 (but not stage 3) were more likely to undergo bariatric surgery compared to patients without diabetes (stage 2: 1.24 [1.00, 1.54] and stage 3: 0.89 [0.57, 1.39]).

“To the best of our knowledge this is the first study to assess, using a holistic obesity staging system, if patients opting for bariatric surgery differ from those choosing conservative treatment,” the authors write. “Importantly, the KOSC were applied retrospectively and did not influence treatment choice. The patients and the multidisciplinary team took part in a shared decision-making process. We could not confirm our hypothesis that surgical patients would have higher scores in most domains of the KOSC.”

“This study assessed the KOSC retrospectively and cannot therefore provide information on the usage of KOSC as a clinical tool designed to select patients for lifestyle intervention or bariatric surgery,” the authors conclude. “Future prospective outcome studies are necessary to assess the applicability of the KOSC in terms of supporting the most appropriate treatment choice as a part of the shared decision making process.”

The article was edited from the original article, under the Creative Commons license

To access this paper, please click here

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