[Show abstract][Hide abstract] ABSTRACT: The information provided during the postoperative handover influences the delivery of care of patients in the postoperative recovery unit through their care on the ward. There is a need for a structured and systematic approach to postoperative handover. The aim of this study was to improve postoperative handover through the implementation of a new handover protocol, which involved a handover proforma and standardization of the handover process.
This prospective pre-post intervention study demonstrated the improvement in postoperative handover through standardization. There was a significant reduction in information omissions and task errors and improvement in communication and teamwork with the new handover protocol.
There was a significant reduction in overall information omissions from 9 to 3 (P < .001) omissions per handover and task errors from 2.8 to .8 (P < .001) with the new handover protocol. Teamwork and nurses' satisfaction score significantly improved from a median of 3 to 4 (P < .001) and median of 4 to 5 (P < .001). Duration of handover decreased from a median of 8 to 7 minutes (P < .376).
The study demonstrates that standardization of postoperative handover improved communication and teamwork and reduced information omissions and task errors. There was an improvement in the quality of the handover after the introduction of the new handover protocol, which was easy and simple to use.
American journal of surgery 10/2013; 206(4):494-501. · 2.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Part of the ongoing healthcare debate is the care of uninsured patients. A common theory is that without regular outpatient care, these patients present to the hospital in the late stages of disease and therefore have worse outcomes. The purpose of this study was to evaluate any differences in outcomes after laparoscopic cholecystectomies between insured and uninsured patients. METHODS: We reviewed all laparoscopic cholecystectomies (LC) done in our institution between 2006 and 2009. Patients were divided into two groups: insured patients (IP) and uninsured patients (UIP). Outcomes, including conversion and complication rates and postoperative length of stay (LOS), were collected and statistically analyzed using χ(2) and ANOVA tests. RESULTS: There were 1,090 LCs done during the study period: 944 patients (86.6 %) were insured (IP) and 146 (13.4 %) were uninsured (UIP). In the IP group there were 63/944 (6.7 %) conversions and 59/944 (6.3 %) complications, while in the UIP group there were 15/146 (10.3 %) conversions and 12/146 (8.2 %) complications. There was no statistically significant difference in either of these categories. Mean (±SD) LOS was 1.73 ± 4.34 days for the IP group and 2.72 ± 4.35 days for the UIP group (p = 0.010, ANOVA). Uninsured patients were much more likely to have emergency surgery (99.3 % vs. 47.9 %, p < 0.001, χ(2)). CONCLUSIONS: In our study group, being uninsured did not correlate with having a higher rate of conversion or complications. However, more uninsured patients had their surgery done emergently, and this led to significantly longer lengths of stay. Further research is necessary to study the cost impact of these findings and to see whether insuring these patients can lead to changes in their outcomes.
[Show abstract][Hide abstract] ABSTRACT: Selection of surgical residents is a difficult task, and program directors are interested in identifying the best candidates. Among the qualities being sought after is the ability to acquire surgical knowledge, and eventually do well on their board examinations. During the interview process, many programs use results from the United States Medical Licensing Exam (USMLE) to identify residents they think will do well academically. The purpose of this study was to evaluate a different method of identifying such residents, through the use of a surgery-specific written exam (SSWE).
A retrospective review of residents in our program between 2004 and 2012 was done. A 50-question SSWE was designed and administered to candidates on the day of their interview. Scores on the SSWE and the USMLE were compared with results on the American Board of Surgery In-Training Exam (ABSITE). Correlation coefficients were calculated and compared.
Community based General Surgery residency program.
Forty-three residents had scores available from the SSWE, USMLE Part 1 (USMLE-1), and Part 2 (USMLE-2). There were ABSITE scores available for 38 in postgraduate year (PGY) 1. USMLE-1 had a statistically significant correlation (r = 0.327, p = 0.045) with the ABSITE score in PGY-1 (ABSITE-1), while with USMLE-2 had slightly less correlation (r = 0.314, p = 0.055) with ABSITE-1. However, the SSWE had a much stronger correlation (r = 0.656, p < 0.001) than either of them.
An SSWE is a good method to identify residents who will later do well on the ABSITE. It is a better method than using the more general USMLE. Since the ABSITE has been shown to correlate with performance on board examinations, residency programs interested in identifying candidates that will do well on their board examinations, should consider incorporating an SSWE into their application process.
Journal of Surgical Education 11/2012; 69(6):807-12. · 1.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE:: To investigate the nature of process failures in postoperative care, to assess their frequency and preventability, and to explore their relationship to adverse events. BACKGROUND:: Adverse events are common and are frequently caused by failures in the process of care. These processes are often evaluated independently using clinical audit. There is little understanding of process failures in terms of their overall frequency, relative risk, and cumulative effect on the surgical patient. METHODS:: Patients were observed daily from the first postoperative day until discharge by an independent surgeon. Field notes on the circumstances surrounding any nonroutine or atypical event were recorded. Field notes were assessed by 2 surgeons to identify failures in the process of care. Preventability, the degree of harm caused to the patient, and the underlying etiology of process failures were evaluated by 2 independent surgeons. RESULTS:: Fifty patients undergoing major elective general surgery were observed for a total of 659 days of postoperative care. A total of 256 process failures were identified, of which 85% were preventable and 51% directly led to patient harm. Process failures occurred in all aspects of care, the most frequent being medication prescribing and administration, management of lines, tubes, and drains, and pain control interventions. Process failures accounted for 57% of all preventable adverse events. Communication failures and delays were the main etiologies, leading to 54% of process failures. CONCLUSIONS:: Process failures are common in postoperative care, are highly preventable, and frequently cause harm to patients. Interventions to prevent process failures will improve the reliability of surgical postoperative care and have the potential to reduce hospital stay.
[Show abstract][Hide abstract] ABSTRACT: Appendicitis has always been an indication for an urgent operation, as delay is thought to lead to disease progression and therefore worse outcomes. Recent studies suggest that appendectomy can be delayed slightly without worse outcomes, however the literature is contradictory. The goal of our study was to examine the relationship between this delay to surgery and patient outcomes. We reviewed all patients that underwent an appendectomy in our institution from January 2009 to December 2010. We recorded the time of surgical diagnosis from when both the surgical consult and the CT scan (if done) were completed. The delay from surgical diagnosis to incision was measured, and patients were divided into two groups: early (≤6 hours delay) and late (>6 hours delay). Outcome measures were 30-day complication rate, length of stay, perforation rate, and laparoscopic to open conversion rate. Three hundred and seventy-seven patients had appendectomies in the study period, and 35 patients were excluded as per the exclusion criteria leaving 342 in the study: 269 (78.7%) in the early group and 73 (21.3%) in the late group. Complications occurred in 21 patients (6.1%) with no difference between the groups: 16/253 (5.9%) in the early group and 5/73 (6.8%) in the late group (P = 0.93, χ(2)). The mean (± standard deviation) length of stay was 86.1 ± 67.1 hours in the early group, and 95.9 ± 73.0 hours in the late group. This difference was not significant (P = 0.22). Delaying an appendectomy more than 6 hours, but less than 24 hours from diagnosis is safe and does not lead to worse outcomes. This can help limit the disruption to the schedules of both the surgeon and the operating room.
The American surgeon 08/2012; 78(8):897-900. · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Effective communication is imperative to safe surgical practice. Previous studies have typically focused upon the operating theatre. This study aimed to explore the communication and information transfer failures across the entire surgical care pathway.
Using a qualitative approach, semi-structured interviews were conducted with 18 members of the multidisciplinary team (seven surgeons, five anaesthetists and six nurses) in an acute National Health Service trust. Participants' views regarding information transfer and communication failures at each phase of care, their causes, effects and potential interventions were explored. Interviews were recorded, transcribed verbatim, and submitted to emergent theme analysis. Sampling ceased when categorical and theoretical saturation was achieved.
Preoperatively, lack of communication between anaesthetists and surgeons was the most common problem (13/18 participants). Incomplete handover from the ward to theatre (12/18) and theatre to recovery (15/18) were other key problems. Work environment, lack of protocols and primitive forms of information transfer were reported as the most common cause of failures. Participants reported that these failures led to increased morbidity and mortality. Healthcare staff were strongly supportive of the view that standardisation and systematisation of communication processes was essential to improve patient safety.
This study suggests communication failures occur across the entire continuum of care and the participants opined that it could have a potentially serious impact on patient safety. This data can be used to plan interventions targeted at the entire surgical pathway so as to improve the quality of care at all stages of the patient's journey.
[Show abstract][Hide abstract] ABSTRACT: Communication is important for patient safety in the operating room (OR). Several studies have assessed OR communications qualitatively or have focused on communication in crisis situations. This study used prospective, quantitative observation based on well-established communication theory to assess similarities and differences in communication patterns between open and laparoscopic surgery.
Based on communication theory, a standardized proforma was developed for assessment in the OR via real-time observation of communication types, their purpose, their content, and their initiators/recipients. Data were collected prospectively in real time in the OR for 20 open and 20 laparoscopic inguinal hernia repairs. Assessors were trained and calibrated, and their reliability was established statistically.
During 1,884 min of operative time, 4,227 communications were observed and analyzed (2,043 laparoscopic vs 2,184 open communications). The mean operative duration (laparoscopic, 48 min vs open, 47 min), mean communication frequency (laparoscopic, 102 communications/procedure vs open, 109 communications/procedure), and mean communication rate (laparoscopic, 2.13 communications/min vs open, 2.23 communications/min) did not differ significantly across laparoscopic and open procedures. Communications were most likely to be initiated by surgeons (80-81 %), to be received by either other surgeons (46-50 %) or OR nurses (38-40 %), to be associated with equipment/procedural issues (39-47 %), and to provide direction for the OR team (38-46 %) in open and laparoscopic cases. Moreover, communications in laparoscopic cases were significantly more equipment related (laparoscopic, 47 % vs open, 39 %) and aimed significantly more at providing direction (laparoscopic, 46 % vs open, 38 %) and at consulting (laparoscopic, 17 % vs open, 12 %) than at sharing information (laparoscopic, 17 % vs open, 31 %) (P < 0.001 for all).
Numerous intraoperative communications were found in both laparoscopic and open cases during a relatively low-risk procedure (average, 2 communications/min). In the observed cases, surgeons actively directed and led OR teams in the intraoperative phase. The lack of communication between surgeons and anesthesiologists ought to be evaluated further. Simple, inexpensive interventions shown to streamline intraoperative communication and teamworking (preoperative briefing, surgeons' mental practice) should be considered further.
[Show abstract][Hide abstract] ABSTRACT: Laparoscopic cholecystectomy is the gold-standard procedure for management of symptomatic gallstone disease. Increased rates of conversion to an open procedure, increased postoperative complications, and longer lengths of stay are seen in thick-walled gallbladders. Previous studies have only evaluated gallbladder walls as being thick or not thick, without looking at the degree of thickness. We hypothesized that, the more severe the wall thickening, the greater the chance of conversions and complications, and the longer the lengths of stay.
All attempted laparoscopic cholecystectomies in our institution between 2006 and 2009 were retrospectively reviewed. Patients undergoing cholecystectomy for reasons other than gallstones (e.g., polyps or cancer) and those without preoperative ultrasounds were excluded. Patients were divided into four groups based on the degree of gallbladder wall thickness: normal (1-2 mm), mildly thickened (3-4 mm), moderately thickened (5-6 mm), and severely thickened (7 mm and above). Outcomes were compared amongst the groups.
874 patients were included in the study. There were 68 conversions (7.8 %) and 58 complications (6.6 %). The incidence of conversions was 3.1, 5.1, 14.9, and 16.8 % in the four groups, respectively (p < 0.001, χ (2)), and the incidence of complications was 1.8, 6.7, 9.1, and 13.1 %, respectively (p = 0.001, χ (2)). The mean (± standard deviation, SD) length of stay in days was 1.09 ± 1.42, 1.83 ± 3.24, 2.54 ± 3.40 and 3.54 ± 4.61, respectively [p < 0.001, analysis of variance (ANOVA)].
A greater degree of gallbladder wall thickness is associated with an increased risk of conversion, increased postoperative complications, and longer lengths of stay. Classifying patients according to degree of gallbladder wall thickness gives more accurate assessment of the risk of surgery, as well as potential outcomes.
[Show abstract][Hide abstract] ABSTRACT: Laparoscopic cholecystectomy (LC) is the standard of care for gallstone disease. Some cases will be converted to open surgery and others will have complications, both leading to worse outcomes. The purpose of this study was to evaluate whether an increased body mass index (BMI) is associated with increased rates of conversion or complication.
A retrospective chart review of 1,027 patients who underwent an attempted LC between January 2006 and December 2009 was performed. Patients were divided into five groups depending on their BMI: 18.5-24.9, 25-29.9, 30-34.9, 35-39.9, and ≥ 40. The primary endpoints were conversion rates, complication rates, and postoperative length of stay (LOS). Multivariate logistic regression was used to identify independent risk factors for worse outcomes.
There were 211 (20.5%), 325 (31.6%), 268 (26.1%), 135 (13.1%), and 88 (8.6%) patients in the groups with BMI values of 18.5-24.9, 25-29.9, 30-34.9, 35-39.9, and ≥ 40, respectively. Seventy-three patients (7.1%) required conversion to open surgery, and 64 patients (6.2%) developed complications. The rate of conversion was similar amongst all the BMI groups (P = 0.366), as was the rate of complication (P = 0.483). Mean (± SD) postoperative LOS was 1.74 ± 3.87 days, and there was no difference between the BMI groups (P = 0.596). Male gender and emergent cholecystectomy were independent predictors of increased conversions and complications. Diabetes was a risk factor for conversion, whereas age >65 years was a risk factor for complications.
Increased BMI was not associated with worse outcomes after LC. Compared with normal weight patients, obese and even morbidly obese patients have no increased risk of conversion to open surgery, nor is there an increased risk of perioperative complications. Obese and morbidly obese patients who require a cholecystectomy should be considered in the same category as normal weight patients, and LC should be the standard of care.
[Show abstract][Hide abstract] ABSTRACT: Prompt appendectomy has always been a standard of care because of the risk of progression in pathology. This time honored practice has been recently challenged by studies, suggesting that appendicitis can be operated on electively. The aim of this study is to examine whether delayed intervention in acute appendicitis is safe by correlating the interval from presentation to operation with the operative and postoperative complications. Retrospective review of patients who underwent appendectomy for acute appendicitis in 2009 was done. The following parameters were recorded: demographics, duration from presentation to evaluation by emergency room attending, performing CT scan, surgical consult, and operation. The pathology, post operative complications, and length of stay were also recorded. Patients were divided into two groups: incision time < 10 hours (early group) and incision time > 10 hours (delayed group). The end points chosen for comparison were: 1) laparoscopic to open conversion rate, 2) complications, 3) readmissions, and 4) length of stay. Number of cases totaled 201, with 76 in the < 10 hours group and 125 in the > 10 hours group. The male to female ratio for the < 10 hours group was 54:22 and for the > 10 hours group was 59:66 (P < 0.001). Length of stay for the early group was 75.52 hours and for the delayed group, 89.15 hours (P = 0.04). There was one intra-abdominal abscess in the early group and 10 in the delayed group (P = 0.04). The early group had 0.2 (2.6%) open conversions, and the delayed group had five (4.1%) conversions (P = 0.58). There were six (4.8%) readmissions in the delayed group and none in the early group (P = 0.05). Our study reveals that the complication rate, length of stay, and readmissions are more in the delayed group. Conversion rate was more in the delayed group, but the difference was not significant. We conclude that early surgical intervention is beneficial in acute appendicitis.
The American surgeon 07/2011; 77(7):898-901. · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To assess the feasibility, validity, and reliability of a postoperative Handover Assessment Tool (PoHAT) and to evaluate the current practices of the postoperative handover at 2 large European hospitals.
Postoperative handover is one of the most critical phases in the care of a patient undergoing surgery. However, handovers are largely informal and variable. A thorough understanding of the problem is necessary before safety solutions can be considered.
Postoperative Handover Assessment Tool (PoHAT) was developed through task analysis, semistructured interviews, literature review, and learned society guidelines. Subsequent validation was done by the Delphi technique. Feasibility and reliability were then evaluated by direct observation of handovers at 2 large European hospitals. Outcomes measures included information omissions, task errors, teamwork evaluation, duration of handover, and number of distractions.
The tool was feasible to use and inter-rater reliability was excellent (r = 0.96, P < 0.001). Evaluation of handover at the 2 study sites revealed a median of 8 information omissions per handover at both the centers (IQR 7-10). There were a median of 3 task errors per handover (IQR 2-4). Thirty-five percent of handovers had distractions, which included competing demands for nurse attention, bleeps, and case-irrelevant communication.
This study has established the feasibility, validity, and reliability of a tool for evaluating postoperative handover. In addition to serving as an objective measure of postoperative handover, the tool can also be used to evaluate the efficacy of any intervention developed to improve this process. The study has also shown that postoperative handover is characterized by incomplete transfer of information and failures in the performance of key tasks.
Annals of surgery 04/2011; 253(4):831-7. · 7.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Factors that affect the quality of clinical decisions of multidisciplinary cancer teams (MDTs) are not well understood. We reviewed and synthesised the evidence on clinical, social and technological factors that affect the quality of MDT clinical decision-making.
Electronic databases were searched in May 2009. Eligible studies reported original data, quantitative or qualitative. Data were extracted and tabulated by two blinded reviewers, and study quality formally evaluated.
Thirty-seven studies were included. Study quality was low to medium. Studies assessed quality of care decisions via the effect of MDTs on care management. MDTs changed cancer management by individual physicians in 2-52% of cases. Failure to reach a decision at MDT discussion was found in 27-52% of cases. Decisions could not be implemented in 1-16% of cases. Team decisions are made by physicians, using clinical information. Nursing personnel do not have an active role, and patient preferences are not discussed. Time pressure, excessive caseload, low attendance, poor teamworking and lack of leadership lead to lack of information and deterioration of decision-making. Telemedicine is increasingly used in developed countries, with no detriment to quality of MDT decisions.
Team/social factors affect management decisions by cancer MDTs. Inclusion of time to prepare for MDTs into team-members' job plans, making team and leadership skills training available to team-members, and systematic input from nursing personnel would address some of the current shortcomings. These improvements ought to be considered at national policy level, with the ultimate aim of improving cancer care.
Annals of Surgical Oncology 03/2011; 18(8):2116-25. · 4.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This review aimed to determine the role of single-incision laparoscopic surgery (SILS) in abdominal and pelvic operations.
The Medline, EMBASE, and PsycINFO databases were systematically searched until October 2009 using "single-incision laparoscopic surgery" and related terms as keywords. References from retrieved articles were reviewed to broaden the search
The study included case reports, case series, and empirical studies that reported SILS in abdominal and pelvic operations.
Number of patients, type of instruments, operative time, blood loss, conversion rate, length of hospital stay, length of follow-up evaluation, and complications were extracted from the reviewed items
The review included 102 studies classified as level 4 evidence. Most of these studies investigated SILS in cholecystectomy (n=34), appendectomy (n=24), and nephrectomy (n=17). For these procedures, operative time, hospital stay, and complications were comparable with those of conventional laparoscopy. Conversion to conventional laparoscopy was seldom performed in cholecystectomy (range, 0-24%) and more frequent in appendectomy (range, 0-41%) and nephrectomy (range, 0-33%).
The potential benefits of SILS include superior cosmesis and possibly shorter operative time, lower costs, and a shortened time to full physical recovery. Careful case selection and a low threshold of conversion to conventional laparoscopic surgery are essential. Multicenter, randomized, prospective studies are needed to compare short- and long-term outcome measures against those of conventional laparoscopic surgery.
[Show abstract][Hide abstract] ABSTRACT: Communication failures are a leading cause of error in surgery. Researchers and practitioners have therefore developed different
interventions to improve communications, such as team briefing and pre-operative patient checklists. These different methods
have clear merit. However, they have only dealt with portions of a complex system. Consequently, disparate interventions of
varying kinds may not integrate and build an effective system of communication. We argue that a new view of communication
is needed to improve safety in surgery; the view that communication is more fundamentally as a property of the whole system
of work rather than confined to interpersonal exchanges. Rather than simply add an intervention to the system, interventions
should integrate into the system. To achieve this, we propose a practical strategy to re-engineer the system of communication
for surgery. This demands an analysis of the immediate informational needs within the system of interest, and an account of
the wider system and those ergonomic and human factors shaping the performance of communicators. We illustrate the application
of the method and refer to potential improvements in safety.
Cognition Technology and Work 01/2011; 13:1-10. · 0.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The global prevalence of type 2 diabetes mellitus and impaired glucose metabolism continues to rise in conjunction with the pandemic of obesity. The metabolic Roux-en-Y gastric bypass operation offers the successful resolution of diabetes in addition to sustained weight loss and excellent long-term outcomes in morbidly obese individuals. The procedure consists of the physiological BRAVE effects: (i) Bile flow alteration; (ii) Reduction of gastric size; (iii) Anatomical gut rearrangement and altered flow of nutrients; (iv) Vagal manipulation and (v) Enteric gut hormone modulation. This operation provides anti-diabetic effects through decreasing insulin resistance and increasing the efficiency of insulin secretion. These metabolic outcomes are achieved through weight-independent and weight-dependent mechanisms. These include the foregut, midgut and hindgut mechanisms, decreased inflammation, fat, adipokine and bile metabolism, metabolic modulation, shifts in gut microbial composition and intestinal gluconeogenesis. In a small minority of patients, gastric bypass results in hyperinsulinaemic hypoglycaemia that may lead to nesidioblastosis (pancreatic beta-cell hypertrophy with islet hyperplasia). Elucidating the precise metabolic mechanisms of diabetes resolution and hyperinsulinaemia after surgery can lead to improved operations and disease-specific procedures including 'diabetes surgery'. It can also improve our understanding of diabetes pathogenesis that may provide novel strategies for the management of metabolic syndrome and impaired glucose metabolism.
[Show abstract][Hide abstract] ABSTRACT: We conducted a systematic review of published literature to gain a better understanding of interprofessional information transfer and communication (ITC) in hospital setting in the field of surgical and anesthetic care.
Communication breakdowns are a common cause of surgical errors and adverse events.
Medline, Embase, PsycINFO, Cochrane Database of Systematic Reviews, and hand search of articles bibliography.
Of the 4027 citations identified through the initial electronic search and screened for possible inclusion, 110 articles were retained following title and abstract reviews. Of these, 38 were accepted for this review.
Data were extracted from the studies about objectives, clinical domain, methodology including study design, sample population, tools for assessing communication, results, and limitations.
Information transfer failures are common in surgical care and are distributed across the continuum of care. They not only lead to errors in care provision but also lead to patient harm. Most of the articles have focused on ITC process in different phases especially in operating room. None of the studies have looked at whole of the surgical care process. No standard tool has been developed to capture the ITC process in different teams and to evaluate the effect of various communication interventions. Uses of standardized communication through checklist, proformas, and technology innovations have improved the ITC process, with an effect on clinical and patient outcomes.
ITC deficits adversely affect patient care. There is a need for standard measures to evaluate this process. Effective and standardized communication among healthcare professionals during the perioperative process facilitates surgical safety.
Annals of surgery 08/2010; 252(2):225-39. · 7.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate information transfer and communication (ITC) across the surgical care pathway with the use of Information Transfer and Communication Assessment Tool for Surgery (ITCAS).
Communication failures are the leading cause of surgical errors and adverse events. It is vital to assess the ITC across the entire surgical continuum of care to understand the process, to study teams, and to prioritize the phases for intervention.
Twenty patients undergoing major gastrointestinal procedures were followed through their entire surgical care, and ITC process was assessed using ITCAS. ITCAS consisted of 4 checklists for 4 phases of the surgical care.
ITC failures are distributed across the entire surgical continuum of care. Preprocedural teamwork and postoperative handover phases have the maximum number of ITC failures (61.7% and 52.4%, respectively). Moreover, it was found that information degrades as it crosses from one phase to another. Of patients, 75% had clinical incidents or adverse events because of ITC failures.
The study demonstrated that ITC failures are ubiquitous across surgical care pathway and there is an imminent need to modify current ITC practices. Standardization of ITC through use of checklists, protocols, or information technology is essential to reduce these communication failures.
Annals of surgery 08/2010; 252(2):402-7. · 7.90 Impact Factor