The unrestricted global effort to complete the COOL trial

BACKGROUND

Severe complicated intra-abdominal sepsis (SCIAS) has an increasing incidence with mortality rates over 80% in some settings. Mortality typically results from disruption of the gastrointestinal tract, progressive and self-perpetuating bio-mediator generation, systemic inflammation, and multiple organ failure. A further therapeutic option may be open abdomen (OA) management with negative peritoneal pressure therapy (NPPT) to remove inflammatory ascites and attenuate the systemic damage from SCIAS, although there are definite risks of leaving the abdomen open whenever it might possibly be closed. This potential therapeutic paradigm is the rationale being assessed in the Closed Or Open after Laparotomy (COOL trial) ( https://clinicaltrials.gov/ct2/show/NCT03163095 ). Initially, the COOL trial received Industry sponsorship; however, this funding mandated the use of a specific trademarked and expensive NPPT device in half of the patients allocated to the intervention (open) arm. In August 2022, the 3 M/Acelity Corporation without consultation but within the terms of the contract canceled the financial support of the trial. Although creating financial difficulty, there is now no restriction on specific NPPT devices and removing a cost-prohibitive intervention creates an opportunity to expand the COOL trial to a truly global basis. This document describes the evolution of the COOL trial, with a focus on future opportunities for global growth of the study.

METHODS

The COOL trial is the largest prospective randomized controlled trial examining the random allocation of SCIAS patients intra-operatively to either formal closure of the fascia or the use of the OA with an application of an NPPT dressing. Patients are eligible if they have free uncontained intraperitoneal contamination and physiologic derangements exemplified by septic shock OR severely adverse predicted clinical outcomes. The primary outcome is intended to definitively inform global practice by conclusively evaluating 90-day survival. Initial recruitment has been lower than hoped but satisfactory, and the COOL steering committee and trial investigators intend with increased global support to continue enrollment until recruitment ensures a definitive answer.

DISCUSSION

OA is mandated in many cases of SCIAS such as the risk of abdominal compartment syndrome associated with closure, or a planned second look as for example part of "damage control"; however, improved source control (locally and systemically) is the most uncertain indication for an OA. The COOL trial seeks to expand potential sites and proceed with the evaluation of NPPT agnostic to device, to properly examine the hypothesis that this treatment attenuates systemic damage and improves survival. This approach will not affect internal validity and should improve the external validity of any observed results of the intervention.

TRIAL REGISTRATION

National Institutes of Health ( https://clinicaltrials.gov/ct2/show/NCT03163095 ).

Outcomes of traumatic extremity vascular injuries from a Malaysian level 1 trauma center

BACKGROUND

In Malaysia, management of traumatic vascular injuries is at the discretion of the treating surgeon (trauma or vascular surgery). This study was conducted to report on the epidemiology, mechanism of injury and outcomes of vascular injuries managed in a regional level 1 trauma center.

METHODS

This is a retrospective cohort study of all patients treated for traumatic extremity vascular injuries from January 2018 to December 2020. Demography, mechanism of injury, pre-operative physiologic vital signs, vessel injured, injury severity (NISS, RTS and TRISS score), type of revascularization surgery, fasciotomy, post-operative blood investigations, operative outcomes (amputation, length of stay and ICU admission) and long-term rehabilitation follow-up were recorded and analyzed.

RESULTS

Amongst the 35 recorded vascular injuries only 28 patients had adequate data that were included in the analysis. Majority of patients were males (23/28patients; 82%). Blunt injury to vessels was more likely in motorcycle crashes (16/28patients; 76%) than in automobile crashes (5/28patients; 24%). There were three lower limb amputees (3/3patients; 100%) that had early fasciotomy and were associated with three-fold higher post-operative median (interquartile range) CK levels of 16740 (8157 to 23116) u/l. Only two thirds (16/28 patients) had active rehabilitation follow-up and were back to work after a median duration of four months.

CONCLUSION

Male gender, blunt injury, road traffic crashes and motorcycles were the majority of vascular injuries. Lower limb vascular injuries had poorer outcome with three amputations performed after attempts at revascularization. Fasciotomy and high CK level may be related to higher risk of limb loss. Our study highlights the importance of rehabilitation and long-term follow-up in this cohort of patients.

Isolated blunt iliac artery injury successfully treated with endovascular stent

Common or external iliac artery injury due to blunt trauma is unusual without an associated pelvic fracture. Here we report on a 62 years old man that sustained left external iliac artery thrombosis due to blunt trauma following fall from motorbike. There was no immediate circulatory compromise. Contrasted CT of abdomen revealed an associated left lower abdominal wall traumatic hernia. The iliac artery was intervened with an endovascular stent to restore luminal flow and the hernia was repaired electively. The entire clinical course and management dilemma are described in this article.

Postoperative outcomes in oesophagectomy with trainee involvement

BACKGROUND

The complexity of oesophageal surgery and the significant risk of morbidity necessitates that oesophagectomy is predominantly performed by a consultant surgeon, or a senior trainee under their supervision. The aim of this study was to determine the impact of trainee involvement in oesophagectomy on postoperative outcomes in an international multicentre setting.

METHODS

Data from the multicentre Oesophago-Gastric Anastomosis Study Group (OGAA) cohort study were analysed, which comprised prospectively collected data from patients undergoing oesophagectomy for oesophageal cancer between April 2018 and December 2018. Procedures were grouped by the level of trainee involvement, and univariable and multivariable analyses were performed to compare patient outcomes across groups.

RESULTS

Of 2232 oesophagectomies from 137 centres in 41 countries, trainees were involved in 29.1 per cent of them (n = 650), performing only the abdominal phase in 230, only the chest and/or neck phases in 130, and all phases in 315 procedures. For procedures with a chest anastomosis, those with trainee involvement had similar 90-day mortality, complication and reoperation rates to consultant-performed oesophagectomies (P = 0.451, P = 0.318, and P = 0.382, respectively), while anastomotic leak rates were significantly lower in the trainee groups (P = 0.030). Procedures with a neck anastomosis had equivalent complication, anastomotic leak, and reoperation rates (P = 0.150, P = 0.430, and P = 0.632, respectively) in trainee-involved versus consultant-performed oesophagectomies, with significantly lower 90-day mortality in the trainee groups (P = 0.005).

CONCLUSION

Trainee involvement was not found to be associated with significantly inferior postoperative outcomes for selected patients undergoing oesophagectomy. The results support continued supervised trainee involvement in oesophageal cancer surgery.

Complete sigmoid colon erosion by an intrauterine contraception device in an ectopic pregnancy: a case report

INTRODUCTION An intrauterine contraceptive device (IUCD) is a common contraception method used for family planning. IUCD erosion into adjacent organs is a rare but serious complication of IUCD use. CASE PRESENTATION A 41-year-old female presented to us with a leaking left ectopic pregnancy. Emergency laparotomy and left salpingectomy were performed. A copper ICUD was found intraperitoneally and part of it had completely eroded into the sigmoid colon. Sigmoid colotomy was performed and the IUCD was removed successfully. Further history revealed that the patient had her IUCD inserted 12 years previously but was forgotten. The patient was discharged well after 4 days of admission. DISCUSSION Erosion of an IUCD into the colon is uncommon and may be asymptomatic or present with bowel perforation and obstruction. There should be a high index of suspicion for pregnancy occurring among women post-IUCD insertion. A misplaced IUCD can cause chronic inflammation of the fallopian tube, which may alter tubal functionality and increase the risk of ectopic pregnancy. Family planning is commonly done in primary health care. Primary care education and counselling are essential to improve awareness of fertile women to prevent similar complications. Periodic examination of IUCD string either by users or primary health-care practitioners is crucial. Ultrasound can be advocated if there are difficulties with the insertion. An abdominal radiograph is useful and should be performed in the case of missing IUCDs.

Comparison of short-term outcomes from the International Oesophago-Gastric Anastomosis Audit (OGAA), the Esophagectomy Complications Consensus Group (ECCG), and the Dutch Upper Gastrointestinal Cancer Audit (DUCA)

BACKGROUND

The Esophagectomy Complications Consensus Group (ECCG) and the Dutch Upper Gastrointestinal Cancer Audit (DUCA) have set standards in reporting outcomes after oesophagectomy. Reporting outcomes from selected high-volume centres or centralized national cancer programmes may not, however, be reflective of the true global prevalence of complications. This study aimed to compare complication rates after oesophagectomy from these existing sources with those of an unselected international cohort from the Oesophago-Gastric Anastomosis Audit (OGAA).

METHODS

The OGAA was a prospective multicentre cohort study coordinated by the West Midlands Research Collaborative, and included patients undergoing oesophagectomy for oesophageal cancer between April and December 2018, with 90 days of follow-up.

RESULTS

The OGAA study included 2247 oesophagectomies across 137 hospitals in 41 countries. Comparisons with the ECCG and DUCA found differences in baseline demographics between the three cohorts, including age, ASA grade, and rates of chronic pulmonary disease. The OGAA had the lowest rates of neoadjuvant treatment (OGAA 75.1 per cent, ECCG 78.9 per cent, DUCA 93.5 per cent; P < 0.001). DUCA exhibited the highest rates of minimally invasive surgery (OGAA 57.2 per cent, ECCG 47.9 per cent, DUCA 85.8 per cent; P < 0.001). Overall complication rates were similar in the three cohorts (OGAA 63.6 per cent, ECCG 59.0 per cent, DUCA 62.2 per cent), with no statistically significant difference in Clavien-Dindo grades (P = 0.752). However, a significant difference in 30-day mortality was observed, with DUCA reporting the lowest rate (OGAA 3.2 per cent, ECCG 2.4 per cent, DUCA 1.7 per cent; P = 0.013).

CONCLUSION

Despite differences in rates of co-morbidities, oncological treatment strategies, and access to minimal-access surgery, overall complication rates were similar in the three cohorts.

Critical adjustments and trauma surgery trends in adaptation to COVID-19 pandemic in Malaysia

Malaysia has one of the highest total numbers of COVID-19 infections amongst the Southeast Asian nations, which led to the enforcements of the Malaysian "Movement Control Order" to prohibit disease transmission. The overwhelming increasing amount of infections has led to a major strain on major healthcare services. This leads to shortages in hospital beds, ventilators and critical personnel protective equipment. This article focuses on the critical adaptations from a general surgery department in Malaysia which is part of a Malaysian tertiary hospital that treats COVID-19 cases. The core highlights of these strategies enforced during this pandemic are: (1) surgery ward and clinic decongestions; (2) deferment of elective surgeries; (3) restructuring of medical personnel work force; (4) utilization of online applications for tele-communication; (5) operating room (OR) adjustments and patient screening; and (6) continuing medical education and updating practices in context to COVID-19. These adaptations were important for the continuation of emergency surgery services, preventing transmission of COVID-19 amongst healthcare workers and optimization of medical personnel work force in times of a global pandemic. In addition, an early analysis on the impact of COVID-19 pandemic and lockdown measures in Malaysia towards the reduction in total number of elective/emergent/trauma surgeries performed is described in this article.

Older age and duration of exposure to type 2 diabetes in selective screening of asymptomatic carotid artery stenosis for primary stroke prevention-A single institution experience

AIMS

To evaluate the incidence and risk factors for carotid artery stenosis amongst asymptomatic type 2 diabetes from a single Malaysian tertiary institution.

METHODS

This is a prospective cross-sectional study of asymptomatic type 2 diabetics selected from the outpatient ophthalmology and endocrine clinics for carotid duplex ultrasound scanning performed by a single radiologist. The duplex ultrasound criteria were based on the North American Symptomatic Carotid Endarterectomy Trial (NASCET) classification of carotid artery stenosis. Univariate and multivariate analysis was performed to identify possible risk factors of carotid artery stenosis.

RESULTS

Amongst the 200 patients, the majority were males (56%) and Malay predominance (58.5%). There were 12/200 patients (6%) with mean age of 69.2 years identified to have carotid artery stenosis. Univariate analysis of patients with asymptomatic carotid artery stenosis identified older age of 69.2 years (p=0.027) and duration of exposure to diabetes of 17.9 years (p=0.024) as significant risk factors.

CONCLUSION

Patients with longer exposure of diabetes and older age were risk factors of carotid artery stenosis in asymptomatic type 2 diabetics. These patients should be considered for selective screening of carotid artery stenosis during primary care visit for early identification and closer surveillance for stroke prevention.

Unexpected complication of arteriovenous fistula of the left common carotid to internal jugular vein following central venous catheterization

Incidence of inadvertent arterial puncture secondary to central venous catheter insertion is not common with an arterial puncture rate of <1%. This is due to the advancements and wide availability of ultrasound to guide its insertion. Formation of arteriovenous fistula after arterial puncture is an unexpected complication. Till date, only five cases (including this case) of acquired arteriovenous fistula formation has been described due to inadvertent common carotid puncture. The present case is a 26-year-old man sustained traumatic brain injuries, chest injuries and multiple bony fractures. During resuscitative phase, attempts at left central venous catheter via left internal jugular vein under ultrasound guidance resulted in inadvertent puncture into the left common carotid artery. Surgical neck exploration revealed that the catheter had punctured through the left internal jugular vein into the common carotid artery with formation of arteriovenous fistula. The catheter was removed successfully and common carotid artery was repaired. Postoperatively, the patient recovered and clinic visits revealed no neurological deficits. From our literature review, the safest method for removal is via endovascular and open surgical removal. The pull/push technique (direct removal with compression) is not recommended due to the high risk for stroke, bleeding and hematoma formation.

Predictors of mortality and validation of burn mortality prognostic scores in a Malaysian burns intensive care unit

BACKGROUND

Majority burn mortality prognostic scores were developed and validated in western populations. The primary objective of this study was to evaluate and identify possible risk factors which may be used to predict burns mortality in a local Malaysian burns intensive care unit. The secondary objective was to validate the five well known burn prognostic scores (Baux score, Abbreviated Burn Severity Index (ABSI) score, Ryan score, Belgium Outcome Burn Injury (BOBI) score and revised Baux score) to predict burn mortality prediction.

METHODS

Patients that were treated at the Hospital Sultan Ismail's Burns Intensive Care (BICU) unit for acute burn injuries between 1 January 2010 to 31 December 2017 were included. Risk factors to predict in-patient burn mortality were gender, age, mechanism of injury, total body surface area burn (TBSA), inhalational injury, mechanical ventilation, presence of tracheotomy, time from of burn injury to BICU admission and initial centre of first emergency treatment was administered. These variables were analysed using univariate and multivariate analysis for the outcomes of death. All patients were scored retrospectively using the five-burn mortality prognostic scores. Predictive ability for burn mortality was analysed using the area under receiver operating curve (AUROC).

RESULTS

A total of 525 patients (372 males and 153 females) with mean age of 34.5 ± 14.6 years were included. There were 463 survivors and 62 deaths (11.8% mortality rate). The outcome of the primary objective showed that amongst the burn mortality risk factors that remained after multivariate analysis were older age (p = 0.004), wider TBSA burn (p < 0.001) and presence of mechanical ventilation (p < 0.001). Outcome of secondary objective showed good AUROC value for the prediction of burn death for all five burn prediction scores (Baux score; AUROC:0.9, ABSI score; AUROC:0.92, Ryan score; AUROC:0.87, BOBI score; AUROC:0.91 and revised Baux score; AUROC:0.94). The revised Baux score had the best AUROC value of 0.94 to predict burns mortality.

CONCLUSION

Current study evaluated and identified older age, total body surface area burns, and mechanical ventilation as significant predictors of burn mortality. In addition, the revised Baux score was the most accurate burn mortality risk score to predict mortality in a Malaysian burn's population.

Rare morbidity of permanent quadriplegia caused by neurenteric cyst of the cervical cord

The incidence of neurenteric cyst (NC) is rare, accounting for 0.3%–1.3% of all spine tumors. The occurrence of quadriplegia caused by NC is even scarcer. Herein we report on a young girl with a rare NC over the C2-C5 spinal cord, which led to the morbidity of permanent quadriplegia despite early surgical intervention. This case highlights the rare morbidity of cervical cord NC presenting with permanent quadriplegia that failed to respond despite early surgical excision.

Clinical Audit of Urosepsis Treated in a Malaysian Surgery Unit

This is a retrospective audit of all patients admitted to the surgical unit for urosepsis from June 2014 to June 2015 at the General Surgery Unit of Hospital Sultan Ismail, Malaysia. Demographics, comorbidities, presenting symptoms, length of stay (LOS), mortality, and associated risk factors were recorded. There were 35 patients treated for urosepsis with a male preponderance of 21/35 patients. Hypertension (n=18) and diabetes (n=10) were the two most common comorbidities. There were five deaths (mortality rate=14.3%) and the main bacterium cultured was Escherichia coli. Age >65, presence of underlying comorbid disease, presence of cancer, urine and blood culture positivity had higher incidence of death but were not statistically significant for urosepsis mortality. However, this result is limited by the small sample size and single centre retrospective data.

A rare presentation of chronic myeloid leukaemia with priapism treated with corporoglandular shunting

Priapism is a rare clinical presentation of a patient with chronic myeloid leukaemia (CML). Herein, we present a young Nepalese man that presented to the emergency department with an acute and painful penile erection for two days. Clinically, he was pale and abdominal examination revealed hepatomegaly. Combined oncologic and initial urological intervention with carvernosal aspiration and intracavernosal phenylephrine failed to achieve detumescence. The patient underwent an emergency corporoglandular shunting eventually. In this case report, we discuss the management compared with previously reported cases.

Pulmonary artery catheter entrapment after mitral valve surgery and the use of transesophageal echocardiography to accurately determine the site of entrapment

The prevalence of pulmonary artery catheter (PAC) entrapment in open-heart surgery is scarce with a prevalence rate of 0.065%. Challenges in managing such cases lie particularly in choosing the modalities (chest roentgenogram, fluoroscopy, and transesophageal echocardiography) to accurately identify the anatomic location and cause of entrapment. In this case, we report a 42-year-old man who underwent mitral valve replacement with PAC entrapment discovered on postoperative day 2 and subsequently underwent retrieval after re-sternotomy. This case also highlights the usefulness of transesophageal echocardiography by the cardiac anesthetist in aiding the surgeons to locate the anatomic location where the catheter was entrapped.

Major tracheobronchial injuries: Management of two rare cases

Tracheobronchial injuries are uncommon and a high level of suspicion is needed for immediate diagnosis and prompt treatment. In this case series, two rare cases of tracheobronchial injuries is described showing variable clinical presentations with different levels of injury. Our first case was seen in a 20 years old male whom had a direct impact on the neck and presented with upper tracheal injury. On arrival, this patient was in respiratory distress and had bilateral pneumothorax. Bilateral chest tube was inserted with subsequent neck exploration. During the neck exploration, anastomosis of the injured trachea was performed. The second case was represented by a 35 years old man with right main bronchial injury. Upon initial presentation, this patient appeared well and was comfortable under room air. However he gradually deteriorated one week after the trauma requiring surgical intervention. Eventually a thoracotomy with primary anastomosis of the bronchial tear was performed. Details of both cases including clinical presentation, imaging and procedures done will be discussed in this article.

A Rare Presentation of Anterior Mediastinal Teratoma Mimicking Valvular Heart Disease with A Systolic Murmur

Extrinsic pulmonary artery stenosis caused by anterior mediastinum teratoma presenting with an ejection systolic murmur is a rare phenomenon. Till date, 15 cases have been reported (inclusive of this case) in the English literatures. Herein we report a 20 year old female with extrinsic pulmonary artery stenosis because of compression by an anterior mediastinal teratoma with a loud ejection systolic murmur. The case report aims to highlight the awareness of such rare presentation of anterior mediastinal teratomas that may mimic congenital valvular heart diseases among clinicians.

Morbidity in an Infant by Superabsorbent Polymer Ingestion

Superabsorbent polymer (SAP) ingestion is a potentially dangerous condition and may lead to morbidity and mortality. A 22-month-old girl presented with intestinal obstruction. At operation a SAP was found as a cause of intestinal obstruction. The child underwent second surgery for anastomotic leak and ileostomy was made.

A Rare Case of Ileocecal Tuberculosis with Pulmonary Embolism and Deep Vein Thrombosis

Venous thromboembolism in tuberculosis is not a well recognised entity. It is a less frequently reported complication of severe pulmonary tuberculosis. It is exceedingly rare when it complicates extrapulmonary tuberculosis. Here, we present a case of 22-year-old young female with abdominal tuberculosis complicated with reverse ileocecal intussusception, deep vein thrombosis and pulmonary embolism. An emergency vena cava filter was inserted prior to a limited right hemicolectomy. In this article, we discuss the rare association of venous thromboembolism with ileocecal tuberculosis.

Prognostic predictors of early mortality from exsanguination in adult trauma: a Malaysian trauma center experience

Background

Trauma mortality due to exsanguination is the second most common cause of death. The objective of this study is to investigate the predictors for early death from exsanguination.

Methods

A prognostic study was done to identify predictors of early mortality due to exsanguination. Data were extracted from our Trauma Surgery Registry database of Sultanah Aminah Hospital, Johor Bahru, Malaysia. All patients who were treated from May 1, 2011 to April 31, 2014 by the trauma team were included. Adult trauma patients included from the Trauma Surgery Registry were divided into two groups for analysis: early death from exsanguination and death from non-exsanguination/survivors. Univariate and multivariate analysis was performed to look for significant predictors of death from exsanguination. Variables analyzed were demography, mechanism of injury, organ injury scale, physiological parameters (systolic blood pressure (SBP), respiratory rate, heart rate, temperature), Glasgow Coma Scale (GCS), Revised Trauma Score (RTS), New Injury Severity Score (NISS), Trauma and Injury Severity Score (TRISS) and cause of death.

Results

A total of 2208 patients with an average age of 36 (±16) years were included. Blunt trauma was the majority with 90.5%, followed by penetrating injuries (9.2%). The overall mortality is 239 out of 2208 (10.8%). Seventy-eight patients (32.6%) died due to central nervous system injury, 69 due to sepsis (28.9%) and 58 due to exsanguination (24.3%). After multivariate analysis, age (OR 1.026 (1.009 to 1.044), p=0.002), SBP (OR 0.985 (0.975 to 0.995), p=0.003) and temperature (OR 0.203 (0.076 to 0.543), p=0.001) were found to be the significant physiological parameters. Intra-abdominal injury and NISS were significant anatomic mortality predictors from exsanguination (p<0.001). Patients with intra-abdominal injury had four times higher risk of mortality from exsanguination (OR 3.948 (2.331 to 6.686), p<0.001).

Discussion

In a Malaysian trauma center, age, SBP, core body temperature, intra-abdominal injury and NISS were significant predictors of early death from exsanguination.

Level of evidence

II.

Large adrenal leiomyoma presented as adrenal incidentaloma in an AIDS patient: A rare entity

The literature on adrenal gland tumour in HIV-infected patients is scarce. We report a 46-year-old Malay man with HIV and Hepatitis C infection presenting with a large nonfunctioning adrenal tumour. Computed tomography showed a large right adrenal tumour with heterogeneous enhancement and central necrosis. A high index of suspicion of a malignant tumour or pheochromocytoma led us to surgical removal of the adrenal gland. In this case report, we highlight important features to look for during pre-op evaluation of a large adrenal mass. Appropriate action should be taken when there is a suspicion of a pheochromocytoma or malignancy.

Rockall risk score in predicting 30 days non-variceal upper gastrointestinal rebleeding in a Malaysian population

OBJECTIVE

the aim of this study was to determine the usefulness of Rockall score in predicting outcomes of 30 days rebleeding, mortality and need for surgical intervention of bleeding gastric and duodenal ulcers.

METHODS

this is a retrospective cohort study of all the emergency endoscopies performed in Hospital sultan Ismail from January 2009 to October 2014 for indications of upper gastrointestinal bleeding (UGIb). Data was extracted from hospital's electronic database and only non-variceal bleeds were included. Rockall score was calculated and outcomes of 30 days rebleeding, mortality and need for surgery was recorded. For each outcome, calibration was done using the Goodness-of-fit tests and discriminative ability was reflected by area under the receiver operating characteristic curve (AUROc).

RESULTS

A total of 1323 patients were included with a male preponderance of 64%. the overall rates of rebleeding were 11.2%, mortality rate of 8.7% and need for surgery was 2%. Low AUROc values for rebleeding (0.63), mortality (0.58) and surgery (0.67) showed poor discriminative ability of Rockall score. the Goodness-of-fit test also revealed that the scoring system was poorly calibrated in outcomes of rebleeding (p <0.001), mortality (p = 0.001) and surgery (p = 0.038) with p-value <0.05. Patients with high risk (scores ≥8) displayed highest rebleeding and mortality rates of 20% respectively in comparison to the moderate (score 3-7) and low (score ≤2) risk groups.

CONCLUSION

Rockall score has a poor discriminative ability and is poorly calibrated for rebleeding, mortality and need for surgery in upper gastrointestinal bleeding. However, it is the best tool we have now to stratify patients into risk groups.