Partial weight recurrence after substantial weight loss was associated with a less favourable cardiovascular risk profile and an increased incidence of both microvascular and macrovascular diseases, according to the latest analysis from the Swedish Obese Subjects (SOS) study. However, their mortality rate was similar to that of those who maintained their weight loss and both groups had lower mortality rates than the control group (non-surgical) receiving standard obesity care.
The study’s authors believe this is the first study to investigate whether long-term morbidity and mortality following significant weight loss differ based on whether the initial weight loss is maintained or partially regained - over 30 years after bariatric surgery.
The SOS study was designed to compare overall mortality between individuals treated with bariatric surgery and usual obesity care. In total, 4,047 individuals were enrolled between September 1987 and January 2001. A bariatric surgery group of 2,007 individuals was formed along with a matched control group of 2,040 participants
The surgery group was divided into weight regain and maintenance groups based on weight changes between baseline and the 1-year follow-up, and between 1- and 4-year follow-up examinations. Those who regained 20% or more of their 1-year weight loss by the 4-year examination were assigned to the weight regain group, while those who regained less than 20% formed the weight maintenance group.
After exclusion of individuals with reoperations, missing data, or who died within the first four years, 1346 (67.1%) individuals were available for assignment to weight regain (n=715) and weight maintenance groups (n=631). Baseline BMI was lower in the weight regain group compared to the weight maintenance group (41.9 ± 4.1 kg/m2 vs 42.8 ± 4.5 kg/m2). Weight regain was influenced by the type of surgery, with gastric bypass resulting in fewer relapses than vertical banded gastroplasty.
At the 1-year examination, the regain and maintenance groups had lost 29.3 ± 11.7 and 31.9 ± 13.8 kg, respectively. From year 1 to year 4, average weight change was +12.7 ± 6.6 and −0.6 ± 7.3 kg in the regain and maintenance groups, respectively. The difference in BMI between the groups observed at year 4 largely persisted over 20 years.
During follow-up, there were 245 major adverse cardiovascular events (myocardial infarction, stroke, and heart failure) in the regain group and 176 in the maintenance group (p=0.003). Microvascular disease was more prevalent in the regain group, with 179 events, compared to 122 events in the maintenance group. During follow-up, there were 216 deaths in the regain group and 184 in the maintenance group, resulting in nearly identical overall mortality rates of 12.4 per 1000 person-years for both groups (p=0.740). However, both the regain and the maintenance group had lower mortality rate compared to the SOS control group receiving usual obesity care.
Cardiovascular disease and cancer were leading causes of death in both groups. The number of deaths from cardiovascular disease was 77 in the regain group and 57 in the maintenance group, respectively (p=0.550). Cancer mortality was also comparable, with 64 vs 62 deaths, respectively (p=0.399). Deaths from other causes followed a similar pattern, with 75 vs 65 deaths, respectively (p=0.849).
The findings were featured in the paper, ‘Health outcomes and their association with weight regain after substantial weight loss in Sweden: a prospective cohort study’, published in The Lancet Regional Health Europe. To access this paper, please click here
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