Impact of sociodemographic factors and baseline health insurance coverage on 1-year outcomes following bariatric surgery

INTRODUCTION

Obesity has emerged as a global health crisis, characterized by rapidly increasing prevalence and growing disease burden. Recent studies reveal sustained growth in both mortality and disability-adjusted life year (DALY) rates attributable to high body mass index (BMI) worldwide from 1990 to 2019: Specifically regarding death, global males increased from 1.0 million (95%UI 0.49, 1.7) to approximately 2.48 million (95%UI 1.5, 3.8); females increased from 1.2 million (95%UI 0.67, 1.9) to approximately 2.54 million (95%UI 1.6, 3.9); in terms of DALY, global males increased from 32.4 million (95%UI 16.4, 53.3) to approximately 82.9 million (95%UI 51.3, 120.3); females increased from 34.9 million (95%UI 20.2, 53.7) to approximately 77.4 million (95%UI 50.9, 111.5)^[1]. Obesity correlates with multiple comorbidities, including hypertension, type 2 diabetes mellitus (T2DM), cardiovascular diseases, osteoarthritis, psychological disorders, and malignancies^[2,3]. It also induces weight-related stigma and bullying among children/adolescents^[4-6], leading to severe psychosocial consequences.

In recent years, the use of anti-obesity medications has steadily increased. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), as a novel class of pharmacological agents for obesity management, have gained considerable attention due to their clinical efficacy and increasing utilization. Multiple clinical trials and epidemiologic studies have demonstrated that patients treated with semaglutide experienced an average weight loss of 14.9% over 68 weeks, accompanied by a reduced incidence of type 2 diabetes^[7-9]. Furthermore, GLP-1RAs have been shown to lower the risk of cardiovascular events, particularly among high-risk populations^[10]. The STEP 4 trial further confirmed that patients who continued GLP-1RA treatment achieved an average weight loss of 10.6% within 20 weeks and maintained significant weight reduction even after discontinuation of the medication^[11]. Nevertheless, bariatric surgery remains the most effective intervention for severe obesity, demonstrating durable outcomes: a 10-year follow-up study reported median excess weight loss (%EWL) of 43.5% (range 2.1%-109.2%) after laparoscopic sleeve gastrectomy (LSG) and 50.7% (1.7%-111.7%) after laparoscopic Roux-en-Y gastric bypass (LRYGB)^[12]. These procedures also improve comorbidity resolution, reduce mortality, and enhance quality of life^[13,14]. However, significant interindividual variability exists, with 4%-53% of patients failing to achieve expected outcomes post-RYGB/LSG^[15-18].

Therefore, identifying determinants of weight loss outcomes is crucial for optimizing therapeutic efficacy. Current research on surgical outcome predictors encompasses psychological profiles, medical history, lifestyle factors, mental health status, demographic characteristics, surgical techniques, and nutritional compliance^[19-21]. However, the potential impacts of Sociodemographic determinants and insurance coverage on weight loss efficacy remain underexplored.

Based on this, this study investigates how educational attainment, family support, birth delivery mode, and minimum medical insurance coverage influence weight loss outcomes and comorbidity resolution at 1-year post-surgery, elucidating social determinants of bariatric treatment efficacy.

METHODS

RESULTS

DISCUSSION

Preoperative factors play a crucial role in improving the outcomes of weight loss surgery. This study employed univariate, multivariate linear, and logistic regression analyses to explore factors influencing the achievement of weight loss goals. Both analyses showed that lack of family support, undergoing LSG, smoking, and high BMI were significantly associated with achieving weight loss goals postoperatively. However, no significant associations were found regarding education level, mode of delivery, or medical insurance coverage.

Studies assessing the relationship between preoperative BMI and postoperative weight loss outcomes have reported two different findings. Some studies indicate a negative correlation between preoperative BMI and postoperative weight loss. For example, Melton GB’s study showed that when weight loss success was defined as achieving at least 40%EWL, a higher BMI was associated with poorer weight loss outcomes^[17]. Similarly, Moreira et al. found that high BMI was negatively correlated with achieving weight loss goals one year after surgery^[23]. Other studies have also identified high BMI as a risk factor for poor weight loss results^[24-27]. On the other hand, many studies exploring the relationship between baseline preoperative factors and weight loss outcomes have shown a positive correlation between high preoperative BMI and better postoperative weight loss. For instance, Vennapusa A’s study indicated that preoperative BMI is a positive predictor of %TWL^[28]. Additionally, Saboor Aftab et al. found a significant positive correlation between preoperative BMI and %EWL at one year postoperatively (r = 0.499, P = 0.009; β = 0.679, P = 0.015)^[29]. Other studies have similarly shown that initial BMI predicts postoperative weight loss outcomes^[30-33]. The results of this study also support a significant correlation between high preoperative BMI and achieving weight loss goals postoperatively. Although the surgical techniques and underlying mechanisms of various bariatric procedures are generally similar, there is consistent evidence that bariatric surgery significantly improves metabolic conditions such as hyperglycemia, dyslipidemia, and hypertension. Moreover, it also leads to marked improvements in hormone-related imbalances. In the present study, the primary outcome measure was the percentage of total weight loss (%TWL). Current evidence suggests that %TWL offers a distinct advantage over other weight loss metrics, as it is less influenced by baseline body weight and provides a more accurate assessment of weight loss outcomes. Notably, one study reported that although the percentage of excess weight loss (%EWL) was higher in patients with a preoperative BMI < 40 kg/m² compared to those with a BMI ≥ 40 kg/m², %TWL was higher in patients with a BMI ≥ 40 kg/m^2[28]. In addition, a systematic review by van Rijswijk et al. emphasized that %TWL more accurately reflects weight loss outcomes than %EWL, particularly in patients with heterogeneous baseline weights^[34]. These findings highlight the variability in outcomes depending on the metric used to assess surgical success, underscoring the need for international consensus on standardized outcome measures for evaluating postoperative weight loss.

Regarding the impact of smoking on weight loss outcomes after bariatric surgery, Andersen et al. found a significant positive correlation between smoking (B: 10.3, P < 0.05) and weight loss^[30]. Similarly, Demirpolat., in a study predicting whether %TWL would reach 20% after one year, also observed a significant relationship between smoking and achieving weight loss goals (B: 0.123, P < 0.05)^[35]. Furthermore, other research has shown that smoking may aid weight loss^[33,36-38], whereas smoking cessation can lead to a certain degree of weight gain. This effect is primarily attributed to increased energy intake, reduced resting metabolic rate, decreased physical activity, and increased lipoprotein lipase activity^[39]. However, some studies have reported no significant association between postoperative weight loss success and smoking status either preoperatively or postoperatively (P > 0.05), although smoking cessation was linked to higher self-reported satisfaction, improved postoperative outcomes, and greater quality of life^[40,41]. Moser et al. analyzed two-year results after LSG and found no significant differences in weight loss benefits between smokers and non-smokers^[42]. However, in another study examining two-year follow-up results after bariatric surgery, smoking was associated with greater weight loss at 6 and 12 months post-RYGB, but no differences were observed at 24 months^[36]. This suggests that smoking may have a certain association with short-term postoperative weight loss, but its impact on long-term weight loss outcomes diminishes over time. Although the results of this study also suggest that smoking may aid in postoperative weight loss, the harms of smoking far outweigh the benefits. Smoking increases the risk associated with weight loss surgery, as studies have shown that patients who smoke are more likely to require unplanned intubation and have higher complication and mortality rates within 30 days compared to non-smokers^[43,44]. Additionally, smoking increases the risk of various cancers^[45-47]. Therefore, although smokers may experience greater short-term weight loss benefits from bariatric surgery compared with non-smokers, current preoperative counseling and preparation protocols consistently recommend smoking cessation to reduce the risk of postoperative complications.

Bariatric Surgery Outcomes Exhibit Considerable Variation Across Countries and Surgical Centers. Pang et al. demonstrated superior excess BMI loss (EBMIL) with RYGB compared to LSG^[48]. Similarly, Lager et al. reported significantly greater weight reduction and better glycemic improvement with RYGB versus LSG during the 1-year postoperative period^[49]. A systematic review corroborated these findings, showing lower percentage excess weight loss (%EWL) with LSG compared to RYGB at 1 year (56.1% vs. 68.3%; P < 0.01)^[50]. Notably, conflicting evidence exists regarding early postoperative outcomes. Paluszkiewicz et al. found no significant difference in %EWL between RYGB and LSG at 1 year (64.2% vs. 67.6%; P > 0.05)^[51]. A randomized controlled trial in a Chinese population revealed comparable BMI reductions between procedures at 1 year, but superior long-term weight maintenance with RYGB during 5-year follow-up^[52]. Conversely, two independent studies by Peterli et al. and Salminen et al. demonstrated equivalent weight loss benefits between LSG and RYGB at 5 years postoperatively^[53,54]. Our findings demonstrate stronger associations between LSG and 1-year weight loss, suggesting that individualized surgical decision making based on comprehensive patient evaluation may achieve short-term outcomes comparable to RYGB. Importantly, procedure selection should prioritize patient-specific characteristics through rigorous preoperative assessment.

Additionally, the results of this study show that patients who did not receive family support preoperatively experienced better postoperative weight loss outcomes. This group may have better compliance and postoperative execution ability. Research on family support based on marital status has shown that marital dissatisfaction is a significant positive predictor of weight loss at one year^[55]. However, some studies have indicated that patients with higher marital satisfaction are more likely to sustain weight loss compared with those with lower marital satisfaction (β = 0.92, SE = 0.37, P = 0.02)^[34]. Nonetheless, it is well established that family support - particularly in the form of dietary involvement and emotional encouragement - is associated with improved weight loss outcomes^[56]. However, this study did not find a relationship between marital status and postoperative weight loss outcomes. Second, in this study, the level of family support was primarily defined based on the patient’s willingness to disclose the surgery to family members and the family’s attitude toward the surgery (i.e., whether they were supportive). This definition may have underestimated the extent of family involvement in other areas. However, long-term weight maintenance largely depends on the patient’s own self-discipline and adherence to follow-up and behavioral interventions. Our findings also suggest that patients with a stronger personal motivation for surgery tend to achieve better postoperative weight outcomes. Therefore, a thorough preoperative assessment of the patient’s psychological status and attitude toward surgery is essential. Furthermore, no significant differences were found in weight loss and metabolic improvement related to healthcare insurance involvement, which aligns with findings from other studies^[57,58]. Similarly, no significant differences in weight loss outcomes were observed based on educational level. However, subgroup analysis revealed that patients with an educational level of junior college or above experienced greater improvements in HbA1c compared with those with a high school education or below. Although there were no significant baseline differences in HbA1c between the two groups, existing research has demonstrated a causal relationship between educational attainment and type 2 diabetes. Notably, Zhang et al. reported that higher educational attainment was significantly associated with a reduced risk of type 2 diabetes (OR = 0.59; P = 1.25 × 10^-16; 95%CI: 0.52-0.67)^[59]. The present study further supports a potential association between educational level and postoperative glycemic improvement following bariatric surgery.

Although this study analyzes the differences in results based on various analytical methods, there are still several limitations. First, the sample size is relatively small, and there is missing follow-up data, which may introduce bias in some of the results. Second, the appropriateness of the outcome measures warrants further investigation and validation. Third, as the study was based on retrospective data, some variables were not assessed using standardized questionnaires, which may have introduced bias into the results. Finally, whether the findings of this study can be generalized to the broader population requires confirmation through further multi-center studies.