Introduction

Obesity is a significant public health concern, impacting more than one-third of American adults [1], with a reported prevalence of obesity at 41.5% and severe obesity at 20.7% [2]. With obesity on the rise since 1999, projections indicate it could reach 55.6% in men and 80.0% in women by 2030 [3].

Common lifestyle interventions like exercising or commercial diet programs to address obesity are ineffective in achieving sustained, long-term weight loss [4]. Likewise, pharmaceutical therapeutics for weight loss, such as GLP-1 agonists, have shown promising early results but also significant side effects [5]. The long-term outcome of stopping the GLP-1 is unknown [6]. Exhibit inadequate efficacy and unsustainable long-term excess weight loss; furthermore, they carry a broad range of short and long-term complications and side effects [7]. Endoscopic bariatric surgical procedures, including endoscopic gastric reduction techniques and balloons, have shown minimal sustained long-term weight loss, with adjustable gastric balloons demonstrating higher complication rates than laparoscopic bariatric surgery [8–10]. On the other hand, bariatric procedures, including duodenal switches (DS), along with their single anastomosis variant (SIPS/SADI), and sleeve gastrectomies have superior outcomes in long-term weight loss maintenance and improvements in obesity-related comorbidities compared to non-surgical methods [11–14].

Following the establishment of the 1991 National Institutes of Health (NIH) Bariatric Consensus Statement, the standard criteria for bariatric surgery require multidisciplinary evaluations by medical, surgical, nutritional, and psychiatric professionals to assess candidacy for bariatric surgery and enhance outcomes by helping patients understand the lifelong post-surgical changes [15]. While these NIH requirements have led to insurance companies mandating preoperative psychological evaluations before bariatric surgeries, literature on the role of these evaluations in predicting weight loss outcomes is mixed, short-term, and inconsistent [16]. Some studies suggest that factors like depression and aggression may contribute to weight regain following bariatric surgery [17–19], while others report no significant association between presurgical psychological conditions—depression, anxiety, history of sexual abuse, self-esteem, and binge eating—and short-term weight loss outcomes [20,21]. The mixed results on this topic are further complicated by concerns about the construct validity of depression self-report measures, which may limit their reliability in predicting weight loss outcomes [22]. Additionally, weight gain as a side effect of mood stabilizers, antidepressants, and other psychotropic medications raises the question of whether postoperative weight gain is due to the underlying mental health condition or the treatment itself [23–26]. Furthermore, psychological evaluations often overlook critical physiological and socioeconomic factors, such as metabolic changes in hormones (like leptin and ghrelin), environmental influences, gender, preoperative BMI, and genetics [27–29].

Along with the inconsistent relationship between psychological evaluations and bariatric surgery outcomes [18,19] across various studies and the overlooking of additional, significant weight-altering factors [17], many studies also generalize their findings across different bariatric procedures or focus specifically on the Roux-en-Y gastric bypass [22]. The laparoscopic sleeve gastrectomy has become increasingly preferred due to its superior weight loss results, better resolution of comorbidities, fewer complications, and shorter operating time compared to other surgeries [30–32]; however, despite its growing popularity, there is a notable lack of research individually examining the impact of psychological evaluations on weight loss success following the laparoscopic sleeve gastrectomy, leaving a noteworthy gap in the literature. This study aims to clarify the role of presurgical psychological evaluations in predicting long-term weight loss outcomes, specifically for patients undergoing laparoscopic sleeve gastrectomy, addressing current inconsistencies in the literature and considering both psychological and physiological factors to enhance the effectiveness of bariatric surgery.

The published literature in support of the psychological evaluation in support of pre-operation workup for weight loss surgery is riddled with opinions, surveys, assumptions, and professional prejudices and biases, and no scientific data in support of this requirement other than in those cases where there is a pre-existing mental health concern [18,33]. The requirement for preoperative psychological evaluation is a form of prejudice [34], a barrier to access, and a threat to health equity.

Materials and methods

This study is a retrospective review of the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) and Surgical Review Corporation (SRC) data registries, as well as the subject charts of 120 patients, spanning the period from 2008 to 2022. These patients had sought a consultation at SRC and MBSAQIP-certified bariatric surgical practices. Data collected from 2008 to 2012 was initially stored in the SRC database before being integrated into the MBSAQIP's database in 2012. Subsequently, this unified database encompassed previously stored and newly collected data from 2012 to 2021. The laparoscopic sleeve gastrectomy (LSG) procedures analyzed in this study were performed at a teaching hospital or an outpatient surgical center based on the patient's medical history, surgical risks, the procedure performed, and third-party reimbursement requirements. All patients had given their consent for the use of their data for research purposes.

Data were gathered regarding the patients’ demographics, procedure type, date of surgery, pre- and postoperative comorbidities, and weight measurements. The data was anonymized, and all identifiable information, including name and patient ID numbers, was removed. Due to the retrospective data analysis conducted on previously collected data and the anonymized status of the information, no Institutional Review Board (IRB) approval was necessary. Patients with missing data were contacted via email and phone to ensure a complete dataset and to avoid selection bias. The patients were then divided into two categories: those who underwent a psychological evaluation and those who did not.

Those who did not disclose any history of psychological or mental illness or relevant medications during both their bariatric surgery and primary care consultations, and whose insurance did not extend coverage to bariatric procedures, were exempt from undergoing psychological evaluation and clearance before surgery. Regardless of their insurance coverage, patients who had previously received mental health care or were on anxiolytic or psychotropic medication were required to have a psychological evaluation by a psychiatrist or psychologist of their choosing as a part of their presurgical workup. The patients’ psychological conditions were chronic and were managed with medication under the supervision of a psychologist or psychiatrist. For this subset of patients, clearance for the LSG was only approved upon receipt of a psychological evaluation clearance by their healthcare provider.

Based on the collected data, metrics such as pre- and postoperative body mass indices (BMIs) and percentage weight loss were calculated. These continuous variables were presented as means with standard deviations and ranges. Statistical comparisons between continuous variables were conducted using a two-sample t-test. The analysis was performed using StatPlus software (StatPlus: Mac, AnalystSoft Inc., Version 8. https://www.analystsoft.com/en/).

Results

Laparoscopic sleeve gastrectomy patient demographics

The study comprised 120 participants, 87 females (72.5%) and 33 males (27.5%). This gender disproportion mirrors findings from recent studies in the field, which indicate that approximately eighty percent of patients undergoing bariatric or metabolic surgery identify as female [35].

Among the 120 participants, 61 of those individuals (50.8%) underwent a psychiatric evaluation prior to the procedure. The mean age of these 61 participants was 42.7 years (SD = 10.75), with an age range of 21.43 to 7and30 years. On average, the time elapsed since the operation for these 61 patients was 5.89 years (SD = 3.02), ranging from 2.08 to 16.33 years. The average preoperative BMI for this cohort was 39.32 kg/m² (SD = 5.62), ranging from 21.74 kg/m² to 54.92 kg/m². On average, it took 2.36 years (SD = 1.97) to reach the lowest weight, with a range of 0.42 to 13.58 years. The average, lowest postoperative BMI within this cohort was 25.17 kg/m² (SD = 4.53), ranging from 18.17 kg/m² to 42.6 kg/m². The mean percent weight loss was 27.76% (SD = 10.28%), ranging from 3.38% to 54.07%. The demographic makeup of this LSG cohort with psychiatric evaluations is outlined in Table 1.

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Table 1. Demographic makeup for LSG patient cohorts.

https://doi.org/10.1371/journal.pone.0344917.t001

Among the 120 LSG patients, 59 (49.2%) were not subjected to a psychological evaluation. As outlined in Table 1, the average time elapsed since this subgroup's operation was 3.47 years (SD 0.91), with a range of 2.00 to 6.42 years. The average age among this subgroup was 41.78 years (SD = 10.59), ranging from 20.04 to 61.55 years. Prior to the operation, the average BMI was 38.82 kg/m² (SD = 7.26), ranging from 26.62 kg/m² to 59.13 kg/m². On average, these individuals experienced a period of 2.52 years (SSD = 3.92 until they reached their lowest weight, with a range of 0.58 to 31.42 years. The average lowest postoperative BMI recorded was 24.99 kg/m² (SD = 4.06), ranging from 16.30 kg/m² to 41.97 kg/m². Notably, the mean weight loss percentage was 29.42% (SD = 10.05%), with individual reductions ranging from 0.59% to 57.98%.

Weight loss comparison for laparoscopic sleeve gastrectomy patients with and without psychological evaluation

Of the 120 patients who underwent the LSG procedure, 50.8% (n = 61) underwent a psychological evaluation, while 49.2% (n = 59) did not. As indicated in Table 2, in the cohort of LSG patients with psychological evaluations, the mean percentage of weight loss from the highest preoperative weight to the current weight was 27.76% (SD = 10.28%), while for those without a psychological evaluation, the mean weight loss was 29.42% (SD = 10.05%). According to a two-tailed t-test, the null hypothesis (H0) posited that there was no difference in the mean percent weight loss between the two groups (μ1 = μ2), while the alternative hypothesis (H1) suggested that there was a difference (μ1 ≠ μ2). The calculated p-value was 0.37. The null hypothesis was not rejected, as the p-value is more significant than the level of 0.05. Therefore, there was no statistically significant difference in the mean percent weight loss between the LSG patients who did and did not undergo a preoperative psychological evaluation.

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Table 2. Two-tailed t-test comparison of the average percent weight loss in LSG patient cohorts with and without psychological evaluations.

https://doi.org/10.1371/journal.pone.0344917.t002

Discussion

Conclusions

In this retrospective cohort, no statistically significant association was observed between preoperative psychological evaluation and intermediate weight loss outcomes following laparoscopic sleeve gastrectomy. Although the study was not powered to exclude a clinically meaningful difference, these findings suggest that routine, non-selective preoperative psychological evaluation may have limited predictive value for postoperative weight loss. Importantly, the absence of an observed association in this dataset does not imply that psychological assessment lacks clinical relevance, but rather that its role may require refinement and more targeted application rather than universal implementation. Further prospective studies with larger sample sizes are warranted to clarify whether psychological evaluations restricted to individuals with pre-existing mental health diagnoses or identified psychosocial vulnerabilities independently influence long-term weight loss outcomes, or whether broader requirements for evaluation contribute to barriers in accessing bariatric care.