Blockchain and population health.

BACKGROUND: Blockchain technology has made great strides in many industries but has yet to impact the world of public health. Population health issues such as outbreak surveillance and controlled substance tracking during emergencies all require a secure, easily accessible database. While the healthcare industry is typically slow to adapt to change, blockchain technology lends itself well to many healthcare issues. METHODS: We utilized a 3D framework using difficulty, novelty and necessity to examine the adoption of blockchain technology in population health, based on the 2D framework of difficulty and novelty as driving factors for the development of foundational technologies in the world of business by Iansiti and Lakhani in The Harvard Business Review. RESULTS: We find that by implementing the third dimension of necessity into an evaluation framework, we can better predict the adoption of technology. We found how different areas of population health fit into the evaluation framework and how necessity can eliminate barriers from implementing novel technologies. CONCLUSION: The byproduct of this paper will be the extension of the Iansiti and Lakhani framework. We will show that blockchain, in all of these domains, shows promise to improve population health as we move past COVID-19 and into the future of healthcare.

Economic Impacts of ABO-Incompatible Live Donor Kidney Transplantation: A National Study of Medicare-Insured Recipients.

The infrequent use of ABO-incompatible (ABOi) kidney transplantation in the United States may reflect concern about the costs of necessary preconditioning and posttransplant care. Medicare data for 26 500 live donor kidney transplant recipients (2000 to March 2011), including 271 ABOi and 62 A2-incompatible (A2i) recipients, were analyzed to assess the impact of pretransplant, transplant episode and 3-year posttransplant costs. The marginal costs of ABOi and A2i versus ABO-compatible (ABOc) transplants were quantified by multivariate linear regression including adjustment for recipient, donor and transplant factors. Compared with ABOc transplantation, patient survival (93.2% vs. 88.15%, p = 0.0009) and death-censored graft survival (85.4% vs. 76.1%, p < 0.05) at 3 years were lower after ABOi transplant. The average overall cost of the transplant episode was significantly higher for ABOi ($65 080) compared with A2i ($36 752) and ABOc ($32 039) transplantation (p < 0.001), excluding organ acquisition. ABOi transplant was associated with high adjusted posttransplant spending (marginal costs compared to ABOc - year 1: $25 044; year 2: $10 496; year 3: $7307; p < 0.01). ABOi transplantation provides a clinically effective method to expand access to transplantation. Although more expensive, the modest increases in total spending are easily justified by avoiding long-term dialysis and its associated morbidity and cost.

OPTN/SRTR 2013 Annual Data Report: economics.

While the costs to Medicare of solid organ transplant are varied and considerable, the total Medicare expenditure of $4.4 billion for solid organ transplant recipients was less than 1 remains one of the most cost-effective surgical interventions in medicine. Heart transplant, the most expensive of the major transplants, is likely cost-effective; SRTR has released an Excel-based tool for investigators to use in exploring this question further. It is likely that most solid organ transplants are cost-effective, given the results presented here and the relatively high cost of heart transplant. However, this must be verified with further study.

Variation in biliary complication rates following liver transplantation: implications for cost and outcome.

Although biliary complications (BCs) have a significant impact on the outcome of liver transplantation (LT), variation in BC rates among transplant centers has not been previously analyzed. BC rate, LT outcome and spending were assessed using linked Scientific Registry of Transplant Recipients and Medicare claims (n = 16,286 LTs). Transplant centers were assigned to BC quartiles based upon risk-adjusted observed to expected (O:E) ratio of BC separately for donation after brain death (DBD) and donation after cardiac death (DCD) donors. The median incidence of BC was 300% greater in the highest versus lowest DBD quartiles (19.0% vs. 5.9%) and varied 250% between DCD quartiles (20.3%-8.4%). Donor and recipient characteristics suggest that high BC centers actually used lower donor risk index organs, fewer split livers and fewer imports (p < 0.001 for all). Transplant at a center in the highest O:E quartile was associated with increased posttransplant mortality (adjusted hazard ratio [aHR] 2.53, p = 0.007) in DCD transplant and increased graft loss (aHR 1.21, p = 0.02) in DBD transplant. Medicare spending was $22,895 (p < 0.0001) higher at centers in highest versus lowest BC quartile. In summary, BC rates vary widely among transplant centers and higher rates are a marker for an increased risk of death, graft failure and health-care spending.

Current Status of Organ Donation.

Organ and tissue donation are options at the end of a patient's life. Physicians and surgeons should have no direct role to play in the solicitation of organ donation and consent for organ recovery from the family of either a brain dead patient or a neurologically devastated patient. Certainly organ and tissue donation, and transplant procedures are life-saving and life-changing for many patients with organ failure and life-altering conditions. Due in part to the disparity between supply and demand for these resources, the potential exists for ethical tensions between the caring physician and surgeon team's advocacy for their patient, and the family at the end of the patient's life, and the process of organ donation. In this article, we will discuss the evolution of the legislative landscape for organ donation in the past decade, the concept of first person consent and its implications, the process of recovery and finally concerns regarding issues of conflict of interest regarding the handling and processing of the donor gift.

Blockchain Applications in the Pharmaceutical Industry.

Methods: We utilized a 4D framework using ease of implementation, novelty, necessity, and fit of the overall industry to examine the adoption of blockchain technology in the pharmaceutical industry. Based on the 2D framework of difficulty and novelty as driving factors for the development of foundational technologies in the world of business by Iansiti and Lakhani, each application was ranked and scored for the best potential implementation. The potential applications proposed in this paper can be grouped into two main categories. The first category, management, includes best-use cases, such as health records, clinical trials, and inventory systems. The second category, monitoring, highlights cases, such as pharmaceutical products, preventing counterfeits, optimizing supply chains, and addressing prescription misuse and abuse. Results: Each application was ranked by the four metrics in the framework, giving the greatest weight to necessity and ease of implementation. Using the highlighted methodology earlier, the applications for best implementation include Prescription Drug Misuse and Abuse Prevention, Prevention of Counterfeits, Clinical Trial Outcomes, and Smart Contracts. Conclusion: Blockchain technology offers a new and promising solution to the pharmaceutical industry's needs. To promote the most appropriate use, each application of blockchain technology must fit within the framework of necessity, ease of implementation, familiarity amongst stakeholders, and fit of the overall industry. By using the extended framework proposed by Iansiti and Lakhani, we show how blockchain, in all these domains, shows promise to improve pharmaceutical industry performance.

Practice Characteristics and Job Satisfaction of Private Practice and Academic Surgeons.

Importance: Private practice and academic surgery careers vary significantly in their daily routine, compensation schemes, and definition of productivity. Data are needed regarding the practice characteristics and job satisfaction of these career paths for surgeons and trainees to make informed career decisions and to identify modifiable factors that may be associated with the health of the surgical workforce. Objective: To obtain and compare the differences in practice characteristics and career satisfaction measures between academic and private practice surgeons. Design, Setting, and Participants: In this cross-sectional survey performed from June 4 to August 1, 2018, an online survey accommodating smartphone, tablet, and desktop formats was distributed by email to 25 748 surgeons who were actively practicing fellows of the American College of Surgeons; had completed a general surgery residency or categorical fellowship in plastic, cardiothoracic, or vascular surgery; and had an active email address on file. Main Outcomes and Measures: Demographic, training, and current practice characteristics were obtained, and satisfaction measures were measured on a 5-point Likert scale and compared by surgeon type. Nonresponse weights adjusted for respondent sex, age, and presence of subspecialty training between respondents and the total surveyed American College of Surgeons population. Results: There were 3807 responses (15% response rate) from surgeons: 1735 academic surgeons (1390 men [80%]; median age, 53 years [interquartile range (IQR), 44-61 years]) and 1464 private practice surgeons (1276 men [87%]; median age, 56 years [IQR, 48-62 years]); 589 surgeons who reported being neither an academic surgeon nor a private practice surgeon and 19 surgeons who did not respond to questions on their practice type were excluded. Academic surgeons reported working a median of 59 hours weekly (IQR, 38-65 hours) compared with 57 hours weekly (IQR, 45-65 hours) for private practice surgeons. Academic surgeons reported more weekly hours performing nonclinical work than did private practice surgeons (24 hours [IQR, 14-38 hours] vs 9 hours [IQR, 4-17 hours]; P < .001). Academic surgeons were more likely than private practice surgeons to be satisfied with their career as a surgeon (1448 of 1706 [85%] vs 1109 of 1420 [78%]; P < .001) and their financial compensation (997 of 1703 [59%] vs 546 of 1416 [39%]; P < .001). Academic surgeons were less likely than private practice surgeons to feel that competition with other surgeons is a threat to financial security (341 of 1705 [20%] vs 559 of 1422 [39%]; P < .001) and less likely to feel that malpractice experience has decreased job satisfaction (534 of 1703 [31%] vs 686 of 1413 [49%]; P < .001). Conclusions and Relevance: This study suggests that, although overall surgeon satisfaction was high, academic surgeons reported higher career satisfaction on several measures when compared with private practice surgeons. Advocacy for private practice surgeons is important to encourage career longevity and sustain US surgeon workforce needs.

Organ donation and utilization in the United States: 1998-2007.

Organ transplantation remains the only life-saving therapy for many patients with organ failure. Despite the work of the Organ Donation and Transplant Collaboratives, and the marked increases in deceased donors early in the effort, deceased donors only rose by 67 from 2006 and the number of living donors declined during the same time period. There continue to be increases in the use of organs from donors after cardiac death (DCD) and expanded criteria donors (ECD). This year has seen a major change in the way organs are offered with increased patient safety measures in those organ offers made by OPOs using DonorNet. Unfortunately, the goals of 75% conversion rates, 3.75 organs transplanted per donor, 10% of all donors from DCD sources and 20% growth of transplant center volume have yet to be reached across all donation service areas (DSAs) and transplant centers; however, there are DSAs that have not only met, but exceeded, these goals. Changes in organ preservation techniques took place this year, partly due to expanding organ acceptance criteria and increasing numbers of ECDs and DCDs. Finally, the national transplant environment has changed in response to increased regulatory oversight and new requirements for donation and transplant provider organizations.

Organ donation and utilization in the United States, 1997-2006.

Deceased organ donation has increased rapidly since 2002, coinciding with implementation of the Organ Donation Breakthrough Collaborative. The increase in donors has resulted in a corresponding increase in the numbers of kidney, liver, lung and intestinal transplants. While transplants for most organs have increased, discard and nonrecovery rates have not improved or have increased, resulting in a decrease in organs recovered per donor (ORPD) and organs transplanted per donor (OTPD). Thus, the expansion of the consent and recovery of incremental donors has frequently outpaced utilization. Meaningful increases in multicultural donation have been achieved, but donations continue to be lower than actual rates of transplantation and waiting list registrations for these groups. To counteract the decline in living donation, mechanisms such as paired donation and enhanced incentives to organ donation are being developed. Current efforts of the collaborative have focused on differentiating ORPD and OTPD targets by donor type (standard and expanded criteria donors and donors after cardiac death), utilization of the OPTN regional structure and enlisting centers to increase transplants to match increasing organ availability.

The pathology of liver-localized post-transplant lymphoproliferative disease: a report of three cases and a review of the literature.

Post-transplantation lymphoproliferative disease (PTLD) is a complication of solid organ transplantation that is typically of B-cell origin and associated with Epstein-Barr virus (EBV). In patients receiving orthotopic liver transplantation (OLT) and treated with cyclosporin A. PTLD typically presents between 6 and 17 months post-transplantation as a systemic illness with involvement of the hepatic graft in a minority of cases. A small number of cases of biopsy-proven PTLD arising in the hepatic graft and limited to the liver and periportal structures have been previously reported. This report describes three additional cases of liver-localized PTLD and reviews similar cases in the literature. The donor/host origin of PTLD may have prognostic significance because the two cases in this report that are of donor origin had different clinical and pathologic features compared with the case of host origin. A rapid PCR-based technique for determining the origin of PTLD is described.

A statewide, population-based, time series analysis of access to liver transplantation.

While the number of patients listed for liver transplant has increased, the pool of donor organs has remained constant. Questions have arisen regarding equitable access to organs. The purpose of this study was to analyze factors associated with access to liver transplantation (LT) using a large, population-based, hospital discharge database. The primary hypothesis was that a variety of factors other than medical need could be associated with access to LT. The rate of LT was defined as the number of liver transplants per admission for liver disease. The data sources were selected to allow a population-based, time-series analysis of all patients admitted with liver disease and those receiving liver transplants in all 157 nonfederal hospitals in North Carolina from 1988 to 1993. The hypotheses of this study were that age, gender, payment source, type of liver disease, distance from the transplant center, and rural county of residence were associated with patients' likelihood of access to LT. During the six years studied, 56,803 patients were admitted with liver disease and 126 underwent liver transplantation (LT). The rate of LT increased from 0.07% to 0.27%. Age, gender, source of payment, type of liver disease, rural county of residence, and distance of residence from the transplant center were associated with rates of transplantation. In the multivariate model, source of payment appeared to have the strongest association with the likelihood of LT. These findings raise important questions associated with equitable access to health care, need for physician education, and transplant center regionalization.

Malnutrition in liver transplant patients: preoperative subjective global assessment is predictive of outcome after liver transplantation.

BACKGROUND: Malnutrition is a common complication of end-stage liver disease. It is frequently not a priority of treatment before liver transplantation. The purpose of this study was to examine whether prospective preoperative nutritional assessment could predict resource utilization and outcome after liver transplantation. METHODS: We retrospectively reviewed 109 sequential orthotopic liver transplants performed at our center between July 1996 and May 1999. Ten patients with fulminant hepatic failure were excluded from the study, leaving 99 patients. Nutritional status was determined at the time of transplantation using subjective global assessment. Wilcoxon rank sum test and rank analysis of variance were used to analyze the data. Results are reported as median (interquartile range). A P value <0.05 was considered significant. RESULTS: Intraoperative transfusion requirements of packed red blood cells and cryoprecipitate was higher in the patients with severe malnutrition in comparison to the mild and moderate groups (severe vs. moderate, 5.5+/-5.5 vs. 3.0+/-6, P=0.026; vs. mild, 1.5+/-3, P<0.0001). The severe group required more fresh-frozen plasma intraoperatively than the mild group (mild vs. severe, 0+/-2 vs. 2+/-6, P=0.0007; vs. moderate, 1+/-4, P=0.071). Patients in the severe group had longer postoperative lengths of stay compared with patients in the moderate and mild groups (severe vs. moderate, 16+/-9 days vs. 10+/-5 days, P=0.0027; vs. mild, 9+/-8 days, P=0.0006). CONCLUSIONS: Subjective global assessment is an excellent independent predictor of outcome in patients undergoing liver transplantation. Severely malnourished patients require more blood products during surgery and have prolonged postoperative length of stay in hospital. Our data suggest that if nutritional repletion is possible in patients with end-stage liver disease before transplantation, patient outcomes could be improved.

Guillain-Barre syndrome in organ and bone marrow transplant patients.

BACKGROUND: Guillain-Barre Syndrome (GBS) is believed to be caused by autoimmune mechanisms that are predominantly T-cell mediated. We report GBS in organ transplant patients and bone marrow transplant patients, both of whom have iatrogenically suppressed T-cell function. METHODS: We reviewed the Duke University Medical Center database from 1989-1999 for all patients who met the criteria for GBS. There were a total of 212 patients. Of these patients, two had undergone organ transplantation and two had undergone autologous bone marrow transplantation. RESULTS: Our report supports the notion that the humoral immune system is involved in the pathogenesis of GBS. Contrary to previous reports, however, functional recovery can occur without return of T-cell function. CONCLUSIONS: This suggests that in organ transplant patients, GBS may be humorally mediated and, even more importantly, responds well to treatment.

Conversion from cyclosporine to FK506 in adult liver transplant recipients: a combined North American and European experience.

BACKGROUND: Although cyclosporine (CsA) made clinical liver transplantation possible, side effects and development of rejection have limited its use. In some patients, conversion to tacrolimus has been necessary to abrogate side effects and to preserve allograft function. METHODS: The results of conversion from CsA to tacrolimus were studied retrospectively in 94 liver allograft recipients from a North American and a European transplant center (Duke University Medical Center, Durham, NC, and Hopital Beaujon, Clichy, France). RESULTS: Forty-seven of 94 patients (50%) were converted for steroid-resistant acute rejection. Conversion was successful in 91% of these patients, whereas 9% of patients developed chronic rejection. A further nine patients were converted for chronic allograft rejection with positive results in eight of nine grafts. Mean serum bilirubin in these nine patients was 8.7 mg/dl before conversion and 2.1 mg/dl 6 months after conversion (P=0.02). Nine patients were converted due to inability to wean steroid. Of these, six patients remains steroid free 1 year after conversion. Twenty-three patients (24%) were converted for nephrotoxicity with a reduction in serum creatinine from 167+/-36 mmol/L to 119+/-28 mmol/L 1 year after conversion (P=0.006). Eight of 11 patients converted for neurotoxicity improved after conversion. Conversion to tacrolimus had no effect on seizure frequency or memory loss. CONCLUSIONS: These results suggest that conversion to tacrolimus from CsA is an appropriate paradigm for graft rescue and treatment of a variety of side effects after liver transplant. However, some situations such as memory loss and hypertension may require other strategies.

Portable power supply for continuous mechanical ventilation during intrahospital transport of critically ill patients with ARDS.

Patients with respiratory failure and poor pulmonary compliance requiring high levels of positive pressure ventilation are at high risk during intrahospital transportation. Most ICU ventilators currently do not have a built-in power supply. Manual bag-valve ventilation frequently is used but often without optimum mean airway pressures or minute ventilation guarantees. Transport ventilators also are limited in their ability to provide high positive end-expiratory pressure, variable inspiratory-expiratory ratios, or pressure-controlled ventilation. The 3M SARNS HELP (Hospital Emergency Limited Power) 115, a portable battery, provides continuous power to ICU ventilators and eliminates ventilator circuit interruption for the critical period of patient transportation.

Current indication of a modified Sugiura procedure in the management of variceal bleeding.

BACKGROUND: The role of gastroesophageal devascularization (Sugiura-rype procedures) for the treatment of variceal bleeding remains controversial. Although Japanese series reported favorable longterm results, the technique has nor been widely accepted in the Western Hemisphere because of a high postoperative morbidity and mortality. The reasons for the different outcomes are unclear. In a multidisciplinary team approach we developed a therapeutic algorithm for patients with recurrent variceal bleeding. STUDY DESIGN: The Sugiura procedure was offered only to patients with well-preserved liver function (Child A or Child B cirrhosis without chronic ascites) who were not candidates for distal splenorenal shunt, transhepatic porto-systemic shunt, or liver transplantation. RESULTS: Fifteen patients with recurrent variceal bleeding underwent a modified Sugiura procedure between September 1994 and September 1997. All but one patient (operative mortality 7%) are alive after a median followup of 4 years. Recurrent variceal bleeding developed in one patient; esophageal strictures, which were successfully treated by endoscopic dilatation, developed in three patients; and one patient experienced mild encephalopathy. Major complications were noted only in patients with impaired liver function (Child B cirrhosis) or when the modified Sugiura was performed in an emergency setting. The presence of cirrhosis or the cause of portal hypertension had no significant impact on the complication rate. CONCLUSIONS: This series was performed during the last decade when all modern therapeutic options for variceal bleeding were available. Our results indicate that the modified Sugiura procedure is an effective rescue therapy in patients who are not candidates for selective shunts, transhepatic porto-systemic shunt, or transplantation. Emergency settings and decreased liver function are associated with an increased morbidity.

Nutrition and metabolic management of AIDS during acute illness.

Diarrhea, sepsis, and malnutrition in the AIDS population are common. Some authors have predicted length of survival based on malnutrition biomarkers alone (degree of weight loss at presentation and serum albumin). Similarly, the hypothesis that malnutrition creates a vicious cycle that potentiates susceptibility to opportunistic infections may be valid. Consideration should be given to combining aggressive enteral and parenteral support with metabolic support in the acute phase of illness and between bouts of infections to facilitate patient care and to restore lean tissue. A skilled nutritional support service can deliver needed metabolic support along with nutritional support to these patients. In this case, we focused on the challenges of treating a new patient with significant malnutrition associated with AIDS of unknown duration; untreated gastrointestinal pathogens associated with substantial acid-base, electrolyte, and micronutrient deficiency; and systemic sepsis.

Orthotopic liver transplant patients require less postoperative morphine than do patients undergoing hepatic resection.

STUDY OBJECTIVE: To compare postoperative morphine use, analgesic efficacy, and side effect profiles in patients following orthotopic liver transplantation (OLTx) and liver resection (LR). DESIGN: Retrospective study. SETTING: Liver transplant and liver resection surgery at a university hospital. PATIENTS: 25 ASA physical status I, II, III, and IV patients undergoing OLTx or liver resection. MEASUREMENTS AND MAIN RESULTS: Morphine use was significantly decreased in the OLTx patients at 6,12, 24, 48, and 72 hours following commencement of patient-controlled analgesia. After commencement of patient-controlled analgesia, pain scores were significantly reduced in the OLTx group compared with those in the liver resection group at 6 and 12 hours. CONCLUSIONS: Orthotopic liver transplant patients experienced less pain and used less morphine postoperatively than did liver resection patients.

Supply and demand for liver transplant surgery: are we training enough surgeons?

The purpose of our study is to determine whether the current level of transplant fellow training is sufficient to meet the future demand for liver transplantation in the United States. Historical data from the Nationwide Inpatient Samples (NIS) for the years 1998 through 2003 were used to construct an estimate of the annual number of liver transplant procedures currently being performed in the United States, and the number projected for each year through 2020. Estimates for the current and future number of surgeons performing liver transplant procedures were also constructed using the same database. The NIS database was used because current national transplant registries do not include information on the number of surgeons performing liver transplant procedures. Using historical data derived from the NIS database, we project that the estimated number of liver transplant procedures per surgeon will remain relatively stable through 2020, with each surgeon performing an average of 12.9 procedures in 2020 compared to 12.9 currently. We conclude that the relationship between demand for liver transplantation in the United States and the supply of liver transplant surgeons will remain stable over the next 15 years.

Statewide, population-based, time-series analysis of the frequency and outcome of pulmonary embolus in 318,554 trauma patients.

UNLABELLED: The low occurrence, nonspecific signs and symptoms, and high rate of associated morbidity and mortality of pulmonary embolus (PE) create major problems in the prevention, diagnosis, and treatment of PE. The purpose of this study was to analyze the frequency and outcome of PE in an entire state's trauma population using a large, population-based, hospital discharge data base. With the inclusion of an entire population, the reported incidence, high risk groups of patients, and specific risk factors regarding PE were assessed. A multivariate, logistic regression model was created from the data to determine predictive power of selected risk factors in patients at risk. METHODS: The data source was a statewide, hospital discharge data base that includes data on all hospitalized patients for all of the hospitals in North Carolina. Data were available from 1988 to 1993. Using primary discharge diagnosis and nine additional ICD-9 coded diagnoses from the discharge abstract, patients were selected by presence of diagnostic codes for traumatic injury (800-959.9) and PE (415.1). Statistical analysis was performed using univariate and multivariate analysis to determine significant risk factors and to create a candidate model for the prediction of risk in the study population. RESULTS: Of 318,554 patients, 952 (0.30%) had a recorded diagnosis of PE. The mortality rate for patients with PE (26%) was 10 times higher than the mortality rate in patients without PE (2.6%). In evaluating specific risk factors, age was a significant predictor of the risk of PE: 0.05% for patients under age 55 and 0.7% in those 55 years and over. The rate of PE, 0.3%, was low for the entire study population, but was highest in patients with injuries of the extremities, 0.53%. Increasing Injury Severity Score and Abbreviated Injury Scale score for determined body systems were also found to correlate with an increasing risk of PE. Over the course of the study, the incidence of PE among patients discharged from non-trauma centers showed a significant decrease. There was also a decrease in the mortality in non-trauma centers for PE. This finding cannot be due to coding changes coincident with the advent of diagnosis related groups because it would be associated with more vigorous combing of charts for diagnoses? It may well be that the use of prophylactic measures in injured patients initially used at trauma centers was adopted by the physicians at non-trauma centers over this time with the resultant decline in PE and associated mortality. From the univariate linear regression models, a logistic regression model was created that confirmed age as the most significant risk factor, followed by Injury Severity Score and Abbreviated Injury Scale score for soft tissue, extremity, and chest. The calculated area under the receiver operator characteristic curve was 0.72. CONCLUSION: Using a large, population-based data base, we were able to determine the reported incidence of PE among trauma patients and establish specific risk factors. The reported incidence of PE in this population is low, 0.30%. The mortality among those with PE, however, is significant at 26%. In this study, age, Injury Severity Score, and injury to specific body regions (soft tissue, extremity, chest) were associated with an increased risk of PE. The investigation of prophylaxis of PE and the general management of injured patients may be influenced by the overall low reported frequency of PE and the specific high risk populations described in this study. In light of the low incidence of PE in patients without specific risk factors, prophylactic interventions cannot be routinely recommended unless their benefits clearly outweigh their risks.