Harvey J. Sugerman

Meta-analysis: surgical treatment of obesity.

Context The effectiveness of surgical therapy in the treatment of obesity is unclear. Contribution Many published studies of obesity surgery have significant limitations, and case series make up much of the evidence. Evidence is complicated by the heterogeneity of procedures studied. However, surgery can result in substantial amounts of weight loss (20 to 30 kg) for markedly obese individuals. One cohort study documented weight loss for 8 years with associated improvements in comorbid conditions, such as diabetes. Complications of surgery appear to occur in about 20% of patients. Implications Those considering surgical treatment for obesity should understand that, although patients who have surgery can lose substantial amounts of weight, the evidence base for these treatments is limited. The Editors The prevalence of obesity in the United States is reaching epidemic proportions. An estimated 30% of individuals met the criteria for obesity in 19992002 (1, 2), and many industrialized countries have seen similar increases. The health consequences of obesity include heart disease, diabetes, hypertension, hyperlipidemia, osteoarthritis, and sleep apnea (3-7). Weight loss of 5% to 10% has been associated with marked reductions in the risk for these chronic diseases and with reducing the incidence of diabetes (8-14). The increasing numbers of obese individuals have led to intensified interest in surgical treatments to achieve weight loss, and a variety of surgical procedures have been used (Figure 1). Bariatric surgery was first performed in 1954 with the introduction of the jejunoileal bypass, which bypasses a large segment of small intestine by connecting proximal small intestine to distal small intestine. With this procedure, weight loss occurs secondary to malabsorption from reduction of upstream pancreatic and biliary contents. However, diarrhea and nutritional deficiencies were common, and this procedure was discontinued because of the complication of irreversible hepatic cirrhosis. With the development of surgical staplers came the introduction of gastroplasty procedures by Gomez in 1981 (15) and Mason in 1982 (16). In these early procedures, the upper portion of the stomach was stapled into a small gastric pouch with an outlet (that is, a stoma) to the remaining distal stomach, which limited the size of the meal and induced early satiety. These procedures were prone to staple-line breakdown or stoma enlargement and were modified in turn by the placement of a band around the stoma (vertical banded gastroplasty). Figure 1. Surgical procedures. The first gastric bypass was reported in 1967 by Mason and Ito (17). It combined the creation of a small gastric pouch with bypassing a portion of the upper small intestine. Additional modifications resulted in the Roux-en-Y gastric bypass (RYGB), a now common operation that involves stapling the upper stomach into a 30-mL pouch and creating an outlet to the downstream small intestine. The new food limb joins with the biliopancreatic intestine after a short distance. This procedure, performed laparoscopically or by using an open approach, generates weight loss by limiting gastric capacity, causing mild malabsorption, and inducing hormonal changes. A second common technique, particularly outside of the United States, is the laparoscopic adjustable gastric band. This device is positioned around the uppermost portion of the stomach and can be adjusted to allow tailoring of the stoma outlet, which controls the rate of emptying of the pouch and meal capacity. Another procedure, preferred by a number of surgeons, is the biliopancreatic bypass, which combines a limited gastrectomy with a long Roux limb intestinal bypass that creates a small common channel (that is, an intestine where food and biliopancreatic contents mix). This procedure can be combined with a duodenal switch, which maintains continuity of the proximal duodenum with the stomach and uses a long limb Roux-en-Y bypass to create a short common distal channel. These latter 2 procedures generate weight loss primarily through malabsorption. Recent worldwide survey data from 2002 and 2003 show that gastric bypass is the most commonly performed weight loss procedure (65.1%) (18). Slightly more than half of gastric bypasses are done laparoscopically. Overall, 24% of cases are laparoscopic adjustable band procedures; 5.4% are vertical banded gastroplasties; and 4.9% are biliopancreatic diversion, with or without the duodenal switch. In California, the number of bariatric cases increased 6-fold between 1996 and 2000 (19), from 1131 cases to 6304; an estimated 140000 procedures were performed in the United States in 2004. With this escalation in the number of procedures, there have been reports of high postoperative complication rates (20-24). Because of these reports and the increasing use of obesity surgery, we were asked to review the literature to estimate the effectiveness of bariatric surgery relative to nonsurgical therapy for weight loss and reduction in preoperative obesity-related comorbid conditions. We were also asked to compare outcomes of surgical techniques. This paper is part of a larger evidence report titled Pharmacological and Surgical Treatment of Obesity, which was prepared for the Agency for Healthcare Research and Quality and is available at www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=hstat1a.chapter.19289. Methods Literature Search and Selection We began with an electronic search of MEDLINE on 16 October 2002, followed by a search of EMBASE and subsequent periodic search updates (on 22 May, 2 June, 12 June, and 3 July 2003). We also assessed existing reviews of surgical therapy for obesity (10, 25, 26). Three reviewers independently reviewed the studies, abstracted data, and resolved disagreements by consensus (2 reviewers per study). The principal investigator settled any unresolved disagreements. We focused on studies that assessed surgery and used a concurrent comparison group. This category includes randomized, controlled trials (RCTs); controlled clinical trials; and cohort studies. A brief scan of the literature showed that these types of studies were rare. Therefore, we also elected to include case series with 10 or more patients, since these studies can be used to assess adverse events and could potentially augment the efficacy data from comparative studies. Publication bias is one potential limitation of analyzing the available literature because poor or negative results are not as likely to be reported as are successes or positive results. Extraction of Study-Level Variables We abstracted data from the articles, including number of patients and comorbid conditions, adverse events, types of outcome measures, and time from intervention until outcome. Detailed data were also collected on characteristics of the study samples, including median age, percentage of women, median baseline weight (in kilograms or body mass index [BMI]), percentage of patients with comorbid conditions at baseline (diabetes, hypertension, dyslipidemia, and sleep apnea), percentage of improvement or resolution of preexisting comorbid conditions, and median follow-up time. We also recorded whether the case series studies reported on consecutive patients. Choice of Outcomes The main outcomes of interest were weight loss, mortality, complication rates, and control of obesity-related comorbid conditions. We used the most commonly reported measurement of weight loss, that is, kilograms, which allowed us to include the greatest number of studies. Among 111 surgical studies reporting weight loss, 43 reported weight loss in kilograms or pounds, 17 reported excess weight loss or some variant, 46 reported both of these outcomes, and 5 reported neither. A total of 89 studies had sufficient data to be included in the weight loss analysis. Because weight loss achieves health benefits primarily by reducing the incidence or severity of weight-related comorbid conditions, we also compared the effects on these outcomes. Quality of life, an important outcome in assessing tradeoffs between benefits and risks, was reported infrequently. Statistical Analyses Because we included both comparative studies and case series, we conducted several types of analyses. The vast number of types of surgical procedures and technical variations required that we aggregate those that were clinically similar and identify the comparisons that were of most interest to the clinical audience. On the basis of discussions with bariatric surgeons, we categorized obesity surgery procedures by procedure type (for example, gastric bypass, vertical banded gastroplasty), laparoscopic or open approach, and specific surgical details such as length of Roux limb (see the larger evidence report for details). Analysis of the Efficacy of Surgical Weight Loss We extracted the mean weight loss and standard deviation at 12 postoperative months and at the maximum follow-up time (36 months). These times were chosen because they are clinically relevant and are most commonly reported. Of the 89 weight loss studies, 71 reported baseline BMI (average, 47.1 kg/m2), 16 reported baseline weight in kilograms or pounds (average, 123.3 kg), and 2 did not report either. The average age of patients was 38 years, and more than three quarters were women. For comparative studies that reported a within-study comparison of 2 procedures, a mean difference was calculated. Mean differences were pooled by using a random-effects model, and 95% CIs were estimated; the same method was used to determine a pooled mean weight loss for each group considering all studies combined. However, mean difference in weight loss was not calculated. Analysis of Surgery Mortality We recorded the number of deaths observed and the total number of patients in each procedure group. If the study self-identified the deaths as early or postoperative or as occurring within 30 days of the surgery, we termed these early deaths. If the

Results of 281 Consecutive Total Laparoscopic Roux-en-Y Gastric Bypasses to Treat Morbid Obesity

ObjectiveTo determine the safety and efficacy of laparoscopic Roux-en-Y gastric bypass for the treatment of morbid obesity. Summary Background DataLaparoscopic Roux-en-Y gastric bypass is a new and technically challenging surgical procedure that requires careful study. MethodsThe authors attempted total laparoscopic Roux-en-Y gastric bypass in 281 consecutive patients. Procedures included 175 proximal bypasses, 12 long-limb bypasses, and 9 revisional procedures from previous bariatric operations. The gastrojejunostomy and jejunojejunostomy were primarily constructed using linear stapling techniques. ResultsEight patients required conversion to an open procedure (2.8%). The mean age of the patients was 41.6 years (range 15–71) and 87% were female. The mean preoperative body mass index was 48.1 kg/m2. The operative time decreased significantly from 234 ± 77 minutes in the first quartile to 162 ± 42 minutes in the most recent quartile. Postoperative length of stay averaged 4 days (range 2–91), with 75% of patients discharged within 3 days. The median hospital stay was 2 days. No patient died after surgery. Complications included three (1.5%) major wound infections (each followed a reoperation for a complication or open conversion), incisional hernia in 5 patients (1.8%), and anastomotic leak with peritonitis in 14 patients (5.1%). Three gastrojejunal leaks were managed without surgery, four by laparoscopic repair/drainage, and three by open repair/drainage. Only three patients had anastomotic leaks in the most recent 164 procedures (1.8%) since the routine use of a two-layer anastomotic technique. Data at 1 year after surgery were available in 69 of 96 (72%) patients (excludes revisions). Weight loss at one year was 70 ± 5% of excess weight. Most comorbid conditions resolved by 1 year after surgery; notably, 88% of patients with diabetes no longer required medications. ConclusionsLaparoscopic gastric bypass demonstrates excellent weight loss and resolution of comorbidities with a low complication rate. The learning curve is evident: operative time and leaks decreased with experience and improved techniques. The primary advantage is an extremely low risk of wound complications, including infection and hernia.

Diabetes and hypertension in severe obesity and effects of gastric bypass-induced weight loss.

ObjectiveTo evaluate the preoperative relationships of hypertension and diabetes mellitus in severe obesity and the effects of gastric bypass (GBP)-induced weight loss. Summary Background DataSevere obesity is associated with multiple comorbidities, particularly hypertension and type 2 diabetes mellitus, that may affect life expectancy. MethodsThe database of patients who had undergone GBP by one general surgeon at a university hospital between September 1981 and January 2000 was queried as to weight, body mass index (BMI), pre- and postoperative diabetes, hypertension, and other comorbidities, including sleep apnea, hypoventilation, gastroesophageal reflux, degenerative joint disease, urinary incontinence, venous stasis, and pseudotumor cerebri. ResultsOf 1,025 patients treated, 15% had type 2 diabetes mellitus and 51% had hypertension. Of those with diabetes, 75% also had hypertension. There was a progressive increase in age between patients who had neither diabetes nor hypertension, either diabetes or hypertension, or both diabetes and hypertension. At 1 year after GBP (91% follow-up), patients lost 66 ± 18% excess weight (%EWL) or 35 ± 9% of their initial weight (%WL). Hypertension resolved in 69% and diabetes in 83%. Patients who resolved their hypertension or diabetes had greater %EWL and %WL than those who did not. African-American patients had a higher risk of hypertension than whites before GBP and were less likely to correct their hypertension after GBP. There was significant resolution of other obesity comorbidity problems. At 5 to 7 years after GBP (50% follow-up), %EWL was 59 ± 24 and %WL was 31 ± 13; resolution of hypertension was 66% and diabetes 86%. ConclusionsThese data suggest that type 2 diabetes mellitus and hypertension may be indirectly related to each other through the effects of obesity, but not directly as to cause and effect. The longer a person remains severely obese, the more likely he or she is to develop diabetes, hypertension, or both. GBP-induced weight loss is effective in correcting diabetes, hypertension, and other comorbidities but is related to the %EWL achieved. Severely obese African-Americans were more likely to have hypertension and respond less well to GBP surgery than whites. These data suggest that GBP surgery for severe obesity should be provided earlier to patients to prevent the development of diabetes and hypertension and their complications.

Bariatric Surgery for Severely Obese Adolescents

A 1991 National Institutes of Health Consensus Conference concluded that severely obese adults could be eligible for bariatric surgery if they had a body mass index (BMI) ≥35 kg/m2 with or ≥40 kg/m2 without obesity comorbidity. It was thought at that time that there were inadequate data to support bariatric surgery in severely obese adolescents. An estimated 25% of children in the United States are obese, a number that has doubled over a 30-year period. Very little information has been published on the subject of obesity surgery in adolescents. Therefore we reviewed our 20-year database on bariatric surgery in adolescents. Severely obese adolescents, ranging from 12 to less than 18 years of age, were considered eligible for bariatric surgery according to the National Institutes of Health adult criteria. Gastroplasty was the procedure of choice in the initial 3 years of the study followed by gastric bypass, which was found to be significantly more effective for weight loss in adults. Distal gastric bypass (D-GBP) was used in extremely obese patients (BMI ≥60 kg/m2) before 1992 and long-limb gastric bypass (LL-GBP) was used for super-obese patients (BMI ≥50 kg/m2) after 1992. Laparoscopic gastric bypass was used after 2000. Thirty-three adolescents (27 white, 6 black; 19 females, 14 males) underwent the following bariatric operations between 1981 and June 2001: horizontal gastroplasty in one, vertical banded gastroplasty in two, standard gastric bypass in 17 (2 laparoscopic), LL-GBP in 10, and D-GBP in three. Mean BMI was 52 ±11 kg/m2 (range 38 to 91 kg/m2), and mean age was 16 ± 1 years (range 12.4 to 17.9 years). Preoperative comorbid conditions included the following: type II diabetes mellitus in two patients, hypertension in 11, pseudotumor cerebri in three, gastroesophageal reflux in five, sleep apnea in six, urinary incontinence in two, polycystic ovary syndrome in one, asthma in one, and degenerative joint disease in 11. There were no operative deaths or anastomotic leaks. Early complications included pulmonary embolism in one patient, major wound infection in one, minor wound infections in four, stomal stenoses (endoscopically dilated) in three, and marginal ulcers (medically treated) in four. Late complications included small bowel obstruction in one and incisional hernias in six patients. There were two late sudden deaths (2 years and 6 years postop-eratively), but these were unlikely to have been caused by the bariatric surgical procedure. Revision procedures included one D-GBP to gastric bypass for malnutrition and one gastric bypass to LL-GBP for inadequate weight loss. Regain of most or all of the lost weight was seen in five patients at 5 to 10 years after surgery; however, significant weight loss was maintained in the remaining patients for up to 14 years after surgery. Comorbid conditions resolved at 1 year with the exception of hypertension in two patients, gastroesophageal reflux in two, and degenerative joint disease in seven. Self-image was greatly enhanced; eight patients have married and have children, five patients have completed college, and one patient is currently in college. Severe obesity is increasing rapidly in adolescents and is associated with significant comorbidity and social stigmatization. Bariatric surgery in adolescents is safe and is associated with significant weight loss, correction of obesity comorbidity, and improved self-image and socialization. These data strongly support obesity surgery for those unfortunate individuals who may have difficulty obtaining insurance coverage based on the 1991 National Institutes of Health Consensus Conference statement.

High Failure Rate After Laparoscopic Adjustable Silicone Gastric Banding for Treatment of Morbid Obesity

ObjectiveTo report the results from one of the eight original U.S. centers performing laparoscopic adjustable silicone gastric banding (LASGB), a new minimally invasive surgical technique for treatment of morbid obesity. Summary Background DataLaparoscopic adjustable silicone gastric banding is under evaluation by the Food & Drug Administration in the United States in an initial cohort of 300 patients. MethodsOf 37 patients undergoing laparoscopic placement of the LASGB device, successful placement occurred in 36 from March 1996 to May 1998. Patients have been followed up for up to 4 years. ResultsFive patients (14%) have been lost to follow-up for more than 2 years but at last available follow-up (3–18 months after surgery) had achieved only 18% (range 5–38%) excess weight loss. African American patients had poor weight loss after LASGB compared with whites. The LASGB devices were removed in 15 (41%) patients 10 days to 42 months after surgery. Four patients underwent simple removal; 11 were converted to gastric bypass. The most common reason for removal was inadequate weight loss in the presence of a functioning band. The primary reasons for removal in others were infection, leakage from the inflatable silicone ring causing inadequate weight loss, or band slippage. The patients with band slippage had concomitant poor weight loss. Bands were removed in two others as a result of symptoms related to esophageal dilatation. In 18 of 25 patients (71%) who underwent preoperative and long-term postoperative contrast evaluation, a significantly increased esophageal diameter developed; of these, 13 (72%) had prominent dysphagia, vomiting, or reflux symptoms. Of the remaining 21 patients with bands, 8 currently desire removal and conversion to gastric bypass for inadequate weight loss. Six of the remaining patients have persistent morbid obesity at least 2 years after surgery but refuse to undergo further surgery or claim to be satisfied with the results. Overall, only four patients achieved a body-mass index of less than 35 and/or at least a 50% reduction in excess weight. Thus, the overall need for band removal and conversion to GBP in this series will ultimately exceed 50%. ConclusionsThe authors did not find LASGB to be an effective procedure for the surgical treatment of morbid obesity. Complications after LASGB include esophageal dilatation, band leakage, infection, erosion, and slippage. Inadequate weight loss is common, particularly in African American patients. More study is required to determine the long-term efficacy of the LASGB

Weight loss with vertical banded gastroplasty and Roux-Y gastric bypass for morbid obesity with selective versus random assignment☆

In a previous study, Roux-Y gastric bypass was found to be significantly more effective than vertical banded gastroplasty for weight loss in morbid obesity, especially for patients addicted to sweets, probably as a result of dumping syndrome symptoms. This study evaluated the ability to selectively assign nonsweet eaters to vertical banded gastroplasty and sweet eaters to gastric bypass. Compared with random assignment, the percentage excess weight lost at 2 years improved significantly with both groups combined. In the vertical banded gastroplasty group, the percentage increased from 41 +/- 19 to 55 +/- 19 percent. With selective assignment, the percentage excess weight lost with gastric bypass was still better than that with vertical banded gastroplasty. Weight loss with gastric bypass was still superior to that of vertical banded gastroplasty but at the expense of more complications. Gastric bypass was ineffective in 19 percent of the super obese patients. A combined restrictive, malabsorptive procedure may be necessary in such persons.

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice for the Perioperative Nutritional, Metabolic, and Nonsurgical Support of the Bariatric Surgery Patient

American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery Medical Guidelines for Clinical Practice are systematically developed statements to assist healthcare professionals in medical decision making for specific clinical conditions. Most of the content herein is based on literature reviews. In areas of uncertainty, professional judgment was applied. These guidelines are a working document that reflects the state of the field at the time of publication. Because rapid changes in this area are expected, periodic revisions are inevitable. We encourage medical professionals to use this information in conjunction with their best clinical judgment. The presented recommendations may not be appropriate in all situations. Any decision by practitioners to apply these guidelines must be made in light of local resources and individual patient circumstances. The American Society for Parenteral & Enteral Nutrition fully endorses sections of these guidelines that address the metabolic and nutritional management of the bariatric surgical patient.

A proposed relationship between increased intra-abdominal, intrathoracic, and intracranial pressure.

OBJECTIVES To determine the effect of acutely increased intra-abdominal pressure on pleural pressure, intracranial pressure, and cerebral perfusion pressure, and to clarify the relationship between these parameters. DESIGN Nonrandomized, controlled study. SETTING Laboratory at a university medical center. SUBJECTS Yorkshire swine, weighing 15 to 20 kg. INTERVENTIONS Anesthetized, ventilated swine had a balloon inserted into the peritoneal cavity and catheters placed for measurement of intracranial pressure, pleural pressure, central venous pressure, pulmonary artery occlusion pressure, and mean arterial pressure. Following baseline measurements, intra-abdominal pressure was increased by incrementally inflating the intraperitoneal balloon. All parameters were remeasured 30 mins after each increase in intra-abdominal pressure. Two groups were studied: a) group 1 (n = 9) animals had intra-abdominal pressure increased to 25 mm Hg above baseline, then released; b) group 2 (n = 3) animals underwent sternotomy and pleuropericardotomy to prevent an increase in pleural pressure with increasing intra-abdominal pressure. MEASUREMENTS AND MAIN RESULTS Increase of intra-abdominal pressure to 25 mm Hg above baseline caused significant (p < .05) increases in intracranial pressure (7.3 +/- 0.6 [SEM] to 16.4 +/- 1.9 mm Hg), pleural pressure (4.3 +/- 1.3 to 11.8 +/- 1.9 mm Hg), pulmonary artery occlusion pressure (9.0 +/- 0.6 to 14.3 +/- 0.8 mm Hg), and central venous pressure (6.6 +/- 0.7 to 10.7 +/- 0.9 mm Hg). The cardiac index (3.4 +/- 0.3 to 1.6 +/- 0.1 L/min/m2) and cerebral perfusion pressure (75.6 +/- 3.6 to 62.0 +/- 6.8 mm Hg) deceased significantly (p < .05), whereas mean arterial pressure (82.8 +/- 3.2 to 78.4 +/- 6.6 mm Hg) remained essentially constant. Sternotomy and pleuro-pericardotomy negated all effects of increased intra-abdominal pressure except the decreased cardiac index (1.6 +/- 0.1 to 2.5 +/- 0.2 L/min/m2). CONCLUSIONS Acutely increased intra-abdominal pressure causes a significant increase in intracranial pressure and a decrease in cerebral perfusion pressure. Increased intra-abdominal pressure appears to produce this effect by augmenting pleural and other intrathoracic pressures and causing a functional obstruction to cerebral venous outflow via the jugular venous system. It is possible that the same phenomenon may be why persons with chronically increased intra-abdominal pressure, such as the morbidly obese, suffer from a high frequency rate of idiopathic intracranial hypertension.

Multivariate Analysis of Risk Factors for Death Following Gastric Bypass for Treatment of Morbid Obesity

Objective:To identify the factors that increase mortality for either open or laparoscopic Roux-en-Y gastric bypass. Summary Background Data:Perioperative mortality is the most feared outcome of bariatric surgery, reported to occur in between 0.5% and 1.5% of patients. Methods:The bariatric database at Virginia Commonwealth University was queried for patients who had undergone either an open gastric bypass (O-GBP) or a laparoscopic gastric bypass (L-GBP). A multivariate logistic regression analysis to identify factors related to perioperative mortality was performed. Factors examined included age, gender, body mass index, preoperative weight, hypertension, diabetes mellitus, sleep apnea, obesity hypoventilation syndrome, venous stasis ulcers, intestinal leak, small bowel obstruction, and pulmonary embolus. Results:Since 1992, more than 2000 patients had either an O-GBP (n = 1431) or a L-GBP (n = 580). Of the O-GBP, 547 patients had a proximal GBP (P-GBP) and 884 superobese (body mass index > 50 kg/m2) patients had a long-limb GBP (LL-GBP). The differences in patient demographics, complications, and perioperative mortality rates between L-GBP and O-GBP and P-GBP and LL-GBP patients were examined. Overall, the independent risk factors associated with perioperative death included leak, pulmonary embolus, preoperative weight, and hypertension. Conclusions:The risk factors for perioperative death can be separated into patient characteristics and complications. The access method, open versus laparoscopic, was not independently predictive of death, but the operation type, proximal versus long limb, was predictive. The data do not suggest that superobese patients should not undergo surgery, as they are high risk for early death due to their body weight and comorbidities without surgery. Surgery should not be reserved as a desperate last measure for weight loss.

Experience with over 3,000 open and laparoscopic bariatric procedures: Multivariate analysis of factors related to leak and resultant mortality

Background: Intestinal leak is a potentially lethal complication of Roux en-Y gastric bypass (GBP). Identification of patients at high risk for leak may reduce complication rates of surgeons early in the procedure learning curve. Methods: A total of 3073 patients who underwent GBP were analyzed using univariate and multivariate logistic regression analyses of the following preoperative factors: hypertension (HTN), diabetes mellitus (DM), sleep apnea (SA), age, gender, weight, body mass index (BMI), and surgery type. Multivariate logistic regression analysis was performed for each procedure type. Results: There were 48 (1.5%) deaths. Independent risk factors for death included leak, weight, procedure type, and HTN. A total of 102 (3.2%) leaks were found. Independent factors for leak included age, male gender, SA, and procedure type. Conclusion: The data suggests that older, heavier male patients with multiple comorbid conditions are at increased risk for leak and mortality. Surgeons early in their learning curve should avoid these high-risk patients to reduce complications.