Rule-based categorization deficits in focal basal ganglia lesion and Parkinson's disease patients

Patients with basal ganglia (BG) pathology are consistently found to be impaired on rule-based category learning tasks in which learning is thought to depend upon the use of an explicit, hypothesis-guided strategy. The factors that influence this impairment remain unclear. Moreover, it remains unknown if the impairments observed in patients with degenerative disorders such as Parkinson's disease (PD) are also observed in those with focal BG lesions. In the present study, we tested patients with either focal BG lesions or PD on two categorization tasks that varied in terms of their demands on selective attention and working memory. Individuals with focal BG lesions were impaired on the task in which working memory demand was high and performed similarly to healthy controls on the task in which selective-attention demand was high. In contrast, individuals with PD were impaired on both tasks, and accuracy rates did not differ between on and off medication states for a subset of patients who were also tested after abstaining from dopaminergic medication. Quantitative, model-based analyses attributed the performance deficit for both groups in the task with high working memory demand to the utilization of suboptimal strategies, whereas the PD-specific impairment on the task with high selective-attention demand was driven by the inconsistent use of an optimal strategy. These data suggest that the demands on selective attention and working memory affect the presence of impairment in patients with focal BG lesions and the nature of the impairment in patients with PD.     

Research interests and funding of members of the American Pediatric Surgical Association: report from 2010 American Pediatric Surgical Association Outcomes and Clinical Trials Committee

Objective

There is lack of data relating to the research interests and funding of pediatric surgeons within the United States and Canada. These data may be helpful in promoting basic and clinical research among pediatric surgeons.

Methods

The American Pediatric Surgical Association (APSA) Outcomes and Clinical Trials Committee developed and administered an online survey via e-mail to the APSA membership to help characterize research activities and funding. The survey was available for completion during December of 2009. The survey contained 10 items with a drop-down menu for multiple choice answers and required 5 to 10 minutes to complete. Results based on research interests as well as funding sources were compiled and analyzed.

Results

A total of 275 members, which comprises 27.4% of the APSA membership, completed the survey. Of the respondents, 177 (64%) described being in an academic practice, 44 (16%) in an academically associated private practice, 9 (3.3%) in a private solo practice, 17 (6.2%) in private group practice, and 3 (1%) in the military. A total of 189 (68.7%) respondents stated that they participated in formal research. Respondents also categorized their research interests, and the following were the most common subjects of study (decreasing order of frequency): appendicitis, trauma and critical care, outcomes, minimally invasive surgery, and congenital diaphragmatic hernia. Of those participating in research, 64.5% stated that they have no formal financial support. Of those supported through the National Institutes of Health, funding grants achieved were as follows: R01 (n = 29), K08 (n = 9), K23 (n = 2), and U01 (n = 8).

Conclusions

Research activities are common among APSA members and encompass a wide range of pediatric surgery topics. Strikingly, the overall financial support of these efforts is limited, predominantly supported by the surgeons themselves. Funded respondents attained grants through Public Health Service grants, departmental grants, or private institutions.     

Analysis of adverse events in pediatric surgery using criteria validated from the adult population: justifying the need for pediatric-focused outcome measures

Introduction

Little is known regarding the incidence and financial impact of adverse events associated with the surgical care of children. The purpose of this study was to characterize the epidemiology and resource utilization associated with these events using definitions validated from the adult population.

Methods

We conducted a 6-year audit (Jan 2003-Dec 2008) of adverse events associated with the 100 most common general pediatric surgical procedures from the Pediatric Health Information System database. We audited 23 events as defined by the National Surgical Quality Improvement Project and modified Agency for Healthcare Research and Quality Patient Safety Indicators. Excess length of stay and total hospital charges attributable to events were determined for each procedure after adjusting for confounders.

Results

Overall 30-day incidence of any adverse event was 10.3% in our sample of 331,093 patients. The most common events were transfusions (30% of all events), wound complications (15%), and events associated with central access (11%). The cumulative incidence of serious events including cardiac arrest, stroke, deep venous thrombosis and pulmonary embolish was less than 0.3%. Ten procedures accounted for 62% of all events, and all 10 were associated with significant (P < .01) increases in length of stay and total hospital charges when any event occurred. Circumcisions, soft-tissue biopsies, pyloromyotomies, and repair of abdominal wall hernias accounted for only 3% of events despite comprising nearly 25% of operative volume.

Conclusions

A relatively small number of pediatric surgical procedures contribute to a disproportionate share of adverse events. Although the National Surgical Quality Improvement Project and Agency for Healthcare Research and Quality criteria can identify pediatric procedures associated with a significant risk of morbidity, the relatively high 30-day event rates captured for some procedures may be heavily influenced by underlying co-morbidity profiles not related to the surgical disease or intervention. Furthermore, the validity of applying adult-focused “adverse” event definitions for the pediatric population should be further explored. Collaborative efforts will be needed to develop more clinically meaningful outcome measures for the purpose of quality improvement end points.     

Prefrontal contributions to rule-based and information-integration category learning

Previous research revealed that the basal ganglia play a critical role in category learning [Ell, S. W., Marchant, N. L., & Ivry, R. B. (2006). Focal putamen lesions impair learning in rule-based, but not information-integration categorization tasks. Neuropsychologia, 44(10), 1737–1751; Maddox, W. T. & Filoteo, J. V. (2007). Modeling visual attention and category learning in amnesiacs, striatal-damaged patients and normal aging. In Advances in Clinical-cognitive science: formal modeling and assessment of processes and symptoms (pp. 113–146). Washington DC: American Psychological Association] but less is known about the specific role of prefrontal cortical (PFC) regions in category learning. The current study examined rule-based (RB) and information-integration (II) category learning in 13 patients with damage primarily to ventral PFC regions. After 600 learning trials with feedback, patients were significantly less accurate than matched controls on both RB and II learning. Model-based analysis identified subgroups of patients whose impaired performance in each task was due to the use of sub-optimal learning strategies. Those patients impaired at either II or RB learning, performed significantly worse on the Wisconsin Card Sorting Test, a test of abstract rule formation and the ability to shift and maintain rules. Lesion analysis pointed to damage in a fairly circumscribed region of ventral medial prefrontal cortex as common to the impaired group of patients and those patients without ventral PFC damage mostly performed normally. These results provide further evidence that the ventromedial prefrontal cortex is critically important for the ability to monitor and integrate feedback in order to select and maintain optimal learning strategies.     

Association Between Change in BMD and Fragility Fracture in Women and Men

Our objective was to estimate the relationship between longitudinal change in BMD and fragility fractures. We studied 3635 women and 1417 men 50–85 yr of age in the Canadian Multicentre Osteoporosis Study who had at least two BMD measurements (lumbar spine, femoral neck, total hip, and trochanter) within the first 5 yr of the study and fragility fractures (any, main, forearm/wrist, ribs, hip) within the first 7 yr. Multiple logistic regression was used to model the relationship between baseline BMD, BMD change, and fragility fractures. We found that, among nonusers of antiresorptives, independent of baseline BMD, a decrease of 0.01 g/cm²/yr in total hip BMD was associated with an increased risk of fragility fracture with ORs of 1.15 (95% CI: 1.01; 1.32) in women and 1.34 (95% CI: 1.02; 1.78) in men. The risk of fragility fractures in subgroups such as fast losers and those with osteopenia was better estimated by models that included BMD change than by models that included baseline BMD but excluded BMD change. Although the association between baseline BMD and fragility fractures was similar in users and nonusers of antiresorptives, the association was stronger in nonusers compared with users. These results show that BMD change in both men and women is an independent risk factor for fragility fractures and also predicts fracture risk in those with osteopenia. The results suggest that BMD change should be included with other variables in a comprehensive fracture prediction model to capture its contribution to osteoporotic fracture risk.     

Factors affecting rejection of bariatric patients from an academic weight loss program

BackgroundTo determine the factors affecting rejection of bariatric candidates at an accredited, American College of Surgeons Level 1A, bariatric program. Bariatric surgery “Centers of Excellence” use a multidisciplinary team to screen patients for eligibility for surgery using insurance, medical history, psychological evaluation findings, and the surgeon assessment. Few studies have reported on the frequency or reasons for patients not being accepted for surgery among high-volume academic bariatric programs.MethodsFrom March to September 2007, 299 consecutive patients were accepted for evaluation into an accredited bariatric program and tracked for the incidence of rejection for weight loss surgery. The primary reasons for rejection included a lack of insurance coverage, being medically unfit, psychological or social inappropriateness, and a body mass index (BMI) that did not meet the cutoff (BMI <35 kg/m² or <40 kg/m² without co-morbid conditions).ResultsOf 299 screened patients, 90 (30.1%) were not accepted for surgery by the multidisciplinary team. The most frequent reason was the lack of insurance coverage (47.8%). Primary care physicians were the most common source of patient referral. All but 1 of the patients excluded because of an inadequate BMI (n = 13) had been referred by friends, co-workers, or themselves from information received from the Internet or television.ConclusionApproximately one third of screened patients were not accepted for surgery by an academic bariatric program. Self- or social referral appeared to correlate with rejection because the BMI did not meet the criteria for surgery. This suggests inadequate information among social referral networks and/or in the media. Long-term follow-up will determine the health outcomes of patients not cleared for weight loss surgery.