From July 2014 to June 2016, 37 patients (aged 18–65 years) who underwent LSG at the Department of Gastrointestinal Surgery in Shanghai Tenth People’s Hospital of Tongji University were enrolled in this study. The patients were divided into two groups: obesity group (n = 14, BMI ≥ 28 kg/m2, no acanthosis nigricans, OB) and obesity with acanthosis nigricans group (n = 23, BMI ≥28 kg/m2, with acanthosis nigricans, AN). Patients included in this study were those with complete data on demographics, weight, and clinical outcomes, and eligible for the 3-month follow-up. All patients provided written informed consent prior to the surgical procedure. This study was approved by the Ethics Committee of the Shanghai Tenth People’s Hospital, Tongji University (no.ChiCTR-OCS-12002381).
Inclusion criteria: Obesity was defined with BMI ≥28 kg/m2 according to the guidelines for prevention and control of overweight and obesity in Chinese adults . The following scale for AN was used . Neck severity: 0, Absent or not detectable on close inspection; 1, Present: clearly present on close visual inspection, not visible to the casual observer, extent not measurable; 2, Mild: limited to the base of the skull, does not extend to the lateral margins of the neck (usually < 3 in. in breadth); 3, Moderate: extending to the lateral margins of the neck (posterior border of the sternocleidomastoid, usually 3–6 in.), should not be visible when the participant is viewed from the front; 4, Severe: extending anteriorly (>6 in.), visible when the participant is viewed from the front. Axilla severity: 0, Absent: not detectable on close inspection; 1, Present: clearly present on close visual inspection, not visible to the casual observer, extent not measurable; 2, Mild: localized to the central portion of the axilla, may have gone unnoticed by the participant; 3, Moderate: involving entire axillary fossa, but not visible when the arm is against the participant’s side; 4, Severe: visible from front or back in the unclothed participant when the arm is against the participant’s side. In this study, each subject enrolled with AN had a score greater than 2.
Exclusion criteria included severe hepatic and renal impairments, cardiovascular and cerebrovascular diseases, chronic consumptive diseases such as cancer. Meanwhile, women who were pregnant or lactating were also excluded. Those patients who were clinically verified as having malignant AN were excluded.
All measurements were made before and 3 months post LSG. A basic anthropometric examination, including measurements of body weight, height, neck, waist and hip circumference, and assessment of AN, was performed by trained technicians. Participants were weighed barefoot and in light clothing to the nearest 0.1 kg. Height was measured with a fixed wall stadiometer. Neck circumference was measured to 1 mm accuracy with a plastic tape in a standardized manner, horizontally above the cricothyroid cartilage, just below the laryngeal prominence . The waist circumference was measured at the end of gentle expiration midway between the lowest rib and the iliac crest with the patient standing, central obesity as assessed by WC (≥90 cm in male and ≥85 cm in female), while the hip circumference was measured at the greater trochanter . BMI was calculated as weight (kg) divided by squared height (meters).
Glucolipid metabolism indexes, such as fasting plasma glucose (FPG), fasting insulin (FINS), fasting c-peptide (FCP), total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL) were recorded. IR index was determined using the homeostasis model assessment of insulin resistance (HOMA-IR), which was calculated according to the formula: HOMA-IR = FPG × FINS/22.5. The natural logarithm of HOMA-IR (LNIR) was calculated. Dual-energy X-ray absorptiometry (DXA, APEX220.127.116.11, HOLOGIC, USA) was used to measure body composition. Fat distribution was evaluated by the following parameters: fat mass (FM), lean mass (LM), bone mineral content (BMC), and percent fat mass (%FM). In DXA examination, android and gynoid were used to represent two main types of fat distribution. Android mainly referred to body fat around the abdomen. Gynoid referred to body fat around the buttocks and thighs. FM, LM, BMC, and %FM were measured in the whole body and six different regions including arms, legs, trunk, head, android, and gynoid. Body composition consisted of FM, LM, and BMC. The weight of the whole body and each tested body region included the weight of FM, LM, and BMC. Visceral fat analysis was performed by CoreScan™, a software available for the assessment of visceral fat (mass in g, volume in cm3 and area in cm2) in the android region. Three DXA indexes were calculated: android/gynoid FM (A/G), %FM trunk/%FM legs (trunk/leg), trunk/limb FM (trunk/limb).
Statistical analysis was carried out using SPSS for Windows version 20.0 (IBM, Chicago, IL, USA). All continuous data are presented as the mean ± standard deviation. Independent Student’s t-test was applied in the intergroup comparison, and paired samples t-test was used to test the differences of continuous variables before and after surgery. Correlation analysis was determined using the Pearson coefficient. Differences with P (two-tailed) value <0.05 were considered to be statistically significant.