High-dimensional, massive sample-size Cox proportional hazards regression for survival analysis.

Survival analysis endures as an old, yet active research field with applications that spread across many domains. Continuing improvements in data acquisition techniques pose constant challenges in applying existing survival analysis methods to these emerging data sets. In this paper, we present tools for fitting regularized Cox survival analysis models on high-dimensional, massive sample-size (HDMSS) data using a variant of the cyclic coordinate descent optimization technique tailored for the sparsity that HDMSS data often present. Experiments on two real data examples demonstrate that efficient analyses of HDMSS data using these tools result in improved predictive performance and calibration.

Reassessing mechanism as a predictor of pediatric injury mortality.

BACKGROUND: The use of mechanism of injury as a predictor of injury outcome presents practical challenges because this variable may be missing or inaccurate in many databases. The purpose of this study was to determine the importance of mechanism of injury as a predictor of mortality among injured children. METHODS: The records of children (<15-y-old) sustaining a blunt injury were obtained from the National Trauma Data Bank. Models predicting injury mortality were developed using mechanism of injury and injury coding using either abbreviated injury scale post-dot values (low-dimensional injury coding) or injury International Classification of Diseases, Ninth Revision codes and their two-way interactions (high-dimensional injury coding). Model performance with and without inclusion of mechanism of injury was compared for both coding schemes, and the relative importance of mechanism of injury as a variable in each model type was evaluated. RESULTS: Among 62,569 records, a mortality rate of 0.9% was observed. Inclusion of mechanism of injury improved model performance when using low-dimensional injury coding but was associated with no improvement when using high-dimensional injury coding. Mechanism of injury contributed to 28% of model variance when using low-dimensional injury coding and <1% when high-dimensional injury coding was used. CONCLUSIONS: Although mechanism of injury may be an important predictor of injury mortality among children sustaining blunt trauma, its importance as a predictor of mortality depends on the approach used for injury coding. Mechanism of injury is not an essential predictor of outcome after injury when coding schemes are used that better characterize injuries sustained after blunt pediatric trauma.

Large-scale parametric survival analysis.

Survival analysis has been a topic of active statistical research in the past few decades with applications spread across several areas. Traditional applications usually consider data with only a small numbers of predictors with a few hundreds or thousands of observations. Recent advances in data acquisition techniques and computation power have led to considerable interest in analyzing very-high-dimensional data where the number of predictor variables and the number of observations range between 10(4) and 10(6). In this paper, we present a tool for performing large-scale regularized parametric survival analysis using a variant of the cyclic coordinate descent method. Through our experiments on two real data sets, we show that application of regularized models to high-dimensional data avoids overfitting and can provide improved predictive performance and calibration over corresponding low-dimensional models.

Role of Routine Subhepatic Abdominal Drain Placement following Uncomplicated Laparoscopic Cholecystectomy: A Prospective Randomised Study.

INTRODUCTION: Routine abdominal drainage after laparoscopy cholecystectomy is an issue of considerable debate. Reason for draining is to detect early bile/blood leak and allow CO2 insufflate during laparoscopy to escape via drain site thereby decreased shoulder tip pain and post-operative nausea and vomiting. But some studies show no difference in post-operative nausea /vomiting/pain between drain and no drain group. AIM: To assess the role of drains following uncomplicated laparoscopic cholecystectomy. MATERIALS AND METHODS: This prospective randomized study was conducted in the Department of General Surgery, Government Medical College and Rajindra Hospital, Patiala. Hundred patients of symptomatic gallstones satisfying the selection and exclusion criteria, undergoing uncomplicated laparoscopic cholecystectomy were included in this study, 50 cases with drains in right subhepatic space (Group I) and 50 cases without drains (Group II). Both groups were compared in terms of post-operative shoulder pain, analgesic requirement, nausea and vomiting, hospital stay and analgesic requirement in patient with drains and without drains. SPSS version 16.0 (Chi-Square Test and Fisher-Exact Test) were used for statistical analysis. RESULTS: In this study, average operative time in both the groups was same (p-value 0.977). There was more incidence of nausea /vomiting in no drain group than in drain group. Shoulder tip pain was lower in drain group in first 12 hours post-operative. However, after 12 hours, drain group had higher shoulder tip pain than no drain group. Analgesic requirement was higher in no drain group upto 12 hours after which it was higher in drain group (statistically not significant). In terms of hospital stay patients in drain group had a longer stay in hospital as compared to no drain group (2.96 vs 2.26; p <0.001 statistically significant). CONCLUSION: Use of drains in uncomplicated laparoscopic cholecystectomy is not advantageous; its role in reducing post-operative nausea/vomiting is insignificant. It increases post-operative shoulder tip pain and hospital stay. Therefore, routine use of drains cannot be justified as it increases morbidity without significant advantage.

Association Between Trauma Center Type and Mortality Among Injured Adolescent Patients.

IMPORTANCE: Although data obtained from regional trauma systems demonstrate improved outcomes for children treated at pediatric trauma centers (PTCs) compared with those treated at adult trauma centers (ATCs), differences in mortality have not been consistently observed for adolescents. Because trauma is the leading cause of death and acquired disability among adolescents, it is important to better define differences in outcomes among injured adolescents by using national data. OBJECTIVES: To use a national data set to compare mortality of injured adolescents treated at ATCs, PTCs, or mixed trauma centers (MTCs) that treat both pediatric and adult trauma patients and to determine the final discharge disposition of survivors at different center types. DESIGN, SETTING, AND PARTICIPANTS: Data from level I and II trauma centers participating in the 2010 National Trauma Data Bank (January 1 to December 31, 2010) were used to create multilevel models accounting for center-specific effects to evaluate the association of center characteristics (PTC, ATC, or MTC) on mortality among patients aged 15 to 19 years who were treated for a blunt or penetrating injury. The models controlled for sex; mechanism of injury (blunt vs penetrating); injuries sustained, based on the Abbreviated Injury Scale scores (post-dot values <3 or ≥3 by body region); initial systolic blood pressure; and Glasgow Coma Scale scores. Missing data were managed using multiple imputation, accounting for multilevel data structure. Data analysis was conducted from January 15, 2013, to March 15, 2016. EXPOSURES: Type of trauma center. MAIN OUTCOMES AND MEASURES: Mortality at each center type. RESULTS: Among 29 613 injured adolescents (mean [SD] age, 17.3 [1.4] years; 72.7% male), most were treated at ATCs (20 402 [68.9%]), with the remainder at MTCs (7572 [25.6%]) or PTCs (1639 [5.5%]). Adolescents treated at PTCs were more likely to be injured by a blunt than penetrating injury mechanism (91.4%) compared with those treated at ATCs (80.4%) or MTCs (84.6%). Mortality was higher among adolescents treated at ATCs and MTCs than those treated at PTCs (3.2% and 3.5% vs 0.4%; P < .001). The adjusted odds of mortality were higher at ATCs (odds ratio, 4.19; 95% CI, 1.30-13.51) and MTCs (odds ratio, 6.68; 95% CI, 2.03-21.99) compared with PTCs but was not different between level I and II centers (odds ratio, 0.76; 95% CI, 0.59-0.99). CONCLUSION AND RELEVANCE: Mortality among injured adolescents was lower among those treated at PTCs, compared with those treated at ATCs and MTCs. Defining resource and patient features that account for these observed differences is needed to optimize adolescent outcomes after injury.

An atypical case of meconium periorchitis as paratesticular mass in a neonate.

A 20-day-old boy was presented with left scrotal swelling, clinically diagnosed as hydrocele. Ultrasonographic findings suggested hydrocele with paratesticular mass. Intraoperatively we found paratesticular mass, separate from left testis. Specimen revealed fibroconnective tissue with mucoid degeneration and focal areas of calcification suggesting meconium periorchitis. It is important to consider meconium periorchitis as one of the etiologies, thereby avoiding unnecessary orchidectomies.

Acute Physiological and Chronic Health Evaluation II Score and its Correlation with Three Surgical Strategies for Management of Ileal Perforations.

INTRODUCTION: Ileal perforation peritonitis is a common surgical emergency in the Indian subcontinent and in tropical countries. It is reported to constitute the fifth common cause of abdominal emergencies due to high incidence of enteric fever and tuberculosis in these management based on Acute Physiological and Chronic Health Evaluation II (APACHE II) score. METHODS: The following study was conducted in the Department of General Surgery, Government Medical College, Patiala. A total of 57 patients were studied and divided in to Group I, II, and III. APACHE II score accessed and score between 10 and 19 were blindly randomized into three procedures primary closure, resection-anastomosis, and ileostomy. The outcome was compared. RESULTS: Ileal perforations were most commonly observed in the third and fourth decade of life with male dominance. APACHE II score was accessed and out of total 57 patients, 6 patients had APACHE II score of 0-9, 48 patients had APACHE II score of 10-19, and 3 patients had APACHE II score of ≥20. In APACHE II score 10-19, 15 patients underwent primary closure, 16 patients underwent resection-anastomosis, and 17 patients underwent ileostomy. DISCUSSION AND CONCLUSION: Primary closure of perforation is advocated in patients with single, small perforation (<1 cm) with APACHE II score 10-19 irrespective of duration of perforation. Ileostomy is advocated in APACHE II score 10-19, where the terminal ileum is grossly inflamed with multiple perforations, large perforations (>1 cm), fecal peritonitis, matted bowel loops, intraoperative evidence of caseating lymph nodes, strictures, and an unhealthy gut due to edema.

Patent vitellointestinal duct as paraumblical abcess: A rare presentation.

INTRODUCTION: Umbilical and paraumblical abscess can occur in children with presenting complaint of discharge from umbilical region. However, patent vitello intestinal duct presenting as paraumblical abscess is rare phenomenon. PRESENTATION OF CASE: One year old male child presented with complain of discharge from umbilical region since birth. Incision & drainage done twice thinking it to be paraumblical abscess. DISCUSSION: Vitellointestinal duct as abscess is rare presentation but it should be considered as a differential diagnosis of discharging umbilicus as management of abscess and patent duct are different. CONCLUSION: Patent vitellointestinal duct can present as paraumbilical abscess, and it should be kept in differential diagnosis specifically in children.

Semi-Supervised Kernel Mean Shift Clustering.

Mean shift clustering is a powerful nonparametric technique that does not require prior knowledge of the number of clusters and does not constrain the shape of the clusters. However, being completely unsupervised, its performance suffers when the original distance metric fails to capture the underlying cluster structure. Despite recent advances in semi-supervised clustering methods, there has been little effort towards incorporating supervision into mean shift. We propose a semi-supervised framework for kernel mean shift clustering (SKMS) that uses only pairwise constraints to guide the clustering procedure. The points are first mapped to a high-dimensional kernel space where the constraints are imposed by a linear transformation of the mapped points. This is achieved by modifying the initial kernel matrix by minimizing a log det divergence-based objective function. We show the advantages of SKMS by evaluating its performance on various synthetic and real datasets while comparing with state-of-the-art semi-supervised clustering algorithms.

Skin staples: a safe technique for securing mesh in lichtensteins hernioplasty as compared to suture.

Background. Lichtenstein tension free repair is the most commonly used technique due to cost effectiveness, low recurrence rate, and better patient satisfaction. This study was done to compare the duration of surgery and postoperative outcome of securing mesh with skin staples versus polypropylene sutures in Lichtenstein hernia repair. Materials and Methods. A total of 96 patients with inguinal hernia undergoing Lichtenstein mesh repair were randomly assigned into two groups. The mesh was secured either by using skin staples (group I) or polypropylene sutures (group II). Results. The operation time was significantly reduced from mesh insertion to completion of skin closure in group I (mean 20.7 min) as compared to group II (mean 32.7 min) with significant P value (P < 0.0001) and less complication rate in group I as compared to group II. Conclusion. Mesh fixation with skin staples is as effective as conventional sutures with added advantage of significant reduction in the operating time and complications or recurrence. The staples can be applied much more quickly than sutures for fixing the mesh, thus saving the operating time. Infection rate is significantly decreased with staples.

A Comparative Study between the Outcome of Primary Repair versus Loop Ileostomy in Ileal Perforation.

Introduction. Ileal perforation peritonitis is a common surgical emergency in the Indian subcontinent and in tropical countries. It is reported to constitute the fifth common cause of abdominal emergencies due to high incidence of enteric fever and tuberculosis in these regions. Methods. Sixty proven cases of ileal perforation patients admitted to Surgical Emergency were taken up for emergency surgery. Randomisation was done by senior surgeons by picking up card from both the groups. The surgical management was done as primary repair (group A) and loop ileostomy (group B). Results. An increased rate of postoperative complications was seen in group A when compared with group B with 6 (20%) patients landed up in peritonitis secondary to leakage from primary repair requiring reoperation as compared to 2 (6.67%) in ileostomy closure. A ratio of 1 : 1.51 days was observed between hospital stay of group A to group B. Conclusion. In cases of ileal perforation temporary defunctioning loop ileostomy plays an important role. We recommend that defunctioning ileostomy should be preferred over other surgical options in cases of ileal perforations. It should be recommended that ileostomy in these cases is only temporary and the extra cost and cost of management are not more than the price of life.

Clavicular osteomyelitis: a rare presentation of extra pulmonary tuberculosis.

Clavicular tuberculosis is a rare entity, an unusual case of skeletal tuberculosis. We report a case of rare presentation of clavicular tuberculosis as a non-healing ulcer in the medial two-third and lateral one-third of the clavicle. The clinical picture was confusing because of the development of foul-smelling discharge due to secondary infection. The diagnosis is rarely suspected before biopsies because tumours are much more frequent than infections in this bone. With worldwide resurgence of tuberculosis, clinicians should maintain a high index of suspicion as more infection at unusual sites is being reported.

Generalized projection-based M-estimator.

We propose a novel robust estimation algorithm­the generalized projection-based M-estimator (gpbM), which does not require the user to specify any scale parameters. The algorithm is general and can handle heteroscedastic data with multiple linear constraints for single and multicarrier problems. The gpbM has three distinct stages­scale estimation, robust model estimation, and inlier/outlier dichotomy. In contrast, in its predecessor pbM, each model hypotheses was associated with a different scale estimate. For data containing multiple inlier structures with generally different noise covariances, the estimator iteratively determines one structure at a time. The model estimation can be further optimized by using Grassmann manifold theory. We present several homoscedastic and heteroscedastic synthetic and real-world computer vision problems with single and multiple carriers.

Detection, grading and classification of coronary stenoses in computed tomography angiography.

Recently conducted clinical studies prove the utility of Coronary Computed Tomography Angiography (CCTA) as a viable alternative to invasive angiography for the detection of Coronary Artery Disease (CAD). This has lead to the development of several algorithms for automatic detection and grading of coronary stenoses. However, most of these methods focus on detecting calcified plaques only. A few methods that can also detect and grade non-calcified plaques require substantial user involvement. In this paper, we propose a fast and fully automatic system that is capable of detecting, grading and classifying coronary stenoses in CCTA caused by all types of plaques. We propose a four-step approach including a learning-based centerline verification step and a lumen cross-section estimation step using random regression forests. We show state-of-the-art performance of our method in experiments conducted on a set of 229 CCTA volumes. With an average processing time of 1.8 seconds per case after centerline extraction, our method is significantly faster than competing approaches.