Venous thromboembolism and adolescent and young adult oncology inpatients in US children's hospitals, 2001 to 2008

Late venous thromboembolism in survivors of adolescent and young adult cancer: A population-based study in California

INTRODUCTION

Venous thromboembolism (VTE), a common complication in cancer patients, occurs more often during the initial phase of treatment. However, information on VTE beyond the first two years after diagnosis ('late VTE') is scarce, particularly in young survivors.

METHODS

We examined the risk of, and factors associated with, late VTE among adolescents and young adults (AYA, 15-39 years) diagnosed with cancer (2006-2018) who survived ≥2 years. Data were obtained from the California Cancer Registry linked to hospitalization, emergency department and ambulatory surgery data. We used non-parametric models and Cox proportional hazard regression for analyses.

RESULTS

Among 59,343 survivors, the 10-year cumulative incidence of VTE was 1.93 % (CI 1.80-2.07). The hazard of VTE was higher among those who had active cancer, including progression from lower stages to metastatic disease (Hazard Ratio (HR) = 10.41, 95 % confidence interval (CI): 8.86-12.22), second primary cancer (HR = 2.58, CI:2.01-3.31), or metastatic disease at diagnosis (HR = 2.38, CI:1.84-3.09). The hazard of late VTE was increased among survivors who underwent hematopoietic cell transplantation, those who received radiotherapy, had a VTE history, public insurance (vs private) or non-Hispanic Black/African American race/ethnicity (vs non-Hispanic White). Patients with leukemias, lymphomas, sarcoma, melanoma, colorectal, breast, and cervical cancers had a higher VTE risk than those with thyroid cancer.

CONCLUSIONS

VTE risk remained elevated ≥2 years following cancer diagnosis in AYA survivors. Active cancer is a significant risk factor for VTE. Future studies might determine if late VTE should prompt evaluation for recurrence or second malignancy, if not already known.

Development and validation of thromboembolism diagnostic algorithms in children with cancer from real-world data

OBJECTIVE

To evaluate the accuracy of diagnostic algorithms developed using the International Classification of Diseases (ICD-9-CM and ICD-10-CA) diagnostic codes and physician billing codes for thromboembolism (TE) from health administrative data compared to chart review diagnoses of TE in children with cancer.

METHODS

Using data linkage between the Pediatric Oncology Group of Ontario Network Information System (Ontario pediatric cancer registry) and various administrative data housed at ICES, eight algorithms were developed including a single reference to one of the billing codes, multiple references with varying time intervals, and combinations of various billing codes during primary cancer therapy for the whole cohort and, for early (<04/2002) and later (≥04/2002, solely ICD-10 codes) periods. Reference standard was chart review data from prior studies (from 1990 to 2016) among children (≤19 years) with cancer and radiologically confirmed TE.

RESULTS

Records of 2056 patients diagnosed with cancer at two participating sites during study period were reviewed; 112 had radiologically confirmed TE. The algorithm with addition of anticoagulation utilization codes was the best performing algorithm (sensitivity = 0.76;specificity = 0.85). With use of ICD-10 only codes, sensitivity of the same algorithm improved to 0.84 with specificity of 0.80.

CONCLUSION

This study provides a valid approach for ascertaining pediatric TE using real-world data.

IMPACT

Research in pediatric thrombosis, especially cancer-related thrombosis, is limited mainly due to small-sized studies. Real-world data provide ready access to large and diverse populations. However, there are no validated algorithms for identifying thrombosis in real-world data for children. An algorithm based on combination of thrombosis and anticoagulation utilization codes had 76% sensitivity and 85% specificity to identify diagnosis of thrombosis in children in administrative data. This study provides a valid approach for ascertaining pediatric thrombosis using real-world data and offers a good avenue to advance pediatric thrombosis research.

Venous Thromboembolism among Noncritically Ill Hospitalized Children: Key Considerations for the Pediatric Hospital Medicine Specialist

Venous thromboembolism (VTE) is a leading cause of morbidity and preventable harm among noncritically ill hospitalized children. Several clinical factors relevant to the noncritically ill hospitalized child significantly increase the risk of VTE including the presence of central venous catheters, systemic inflammation, and prolonged immobilization. Although risk mitigation strategies have been described, the diagnosis, treatment, and prevention of VTE require standardization of institutional practices combined with multidisciplinary collaboration among pediatric hospitalists, hematologists, and other care providers. In this narrative review, we summarize the epidemiology of VTE, risk models identifying high-risk conditions associated with VTE, and prevention and treatment strategies. We further describe successful quality improvement efforts implementing institutional VTE risk stratification and thromboprophylaxis procedures. Finally, we highlight unique challenges facing pediatric hospital medicine specialists in the era of the COVID-19 pandemic, including caring for adults admitted to pediatric hospital units, and describe future research opportunities for VTE in the noncritically ill hospitalized child.

The incidence and risk factors for venous thromboembolism in adolescent and young adult oncology patients

BACKGROUND

Venous thromboembolism (VTE) is a known complication among pediatric and adult cancer patients. Adolescent and young adult oncology (AYAO) patients have unique biological and physiological characteristics that make them distinct from other populations. Our objective was to study the VTE incidence, risk factors, and outcomes, which have been understudied in this population.

PROCEDURE

A retrospective case-control study was conducted on AYAO participants with new or relapsed cancer and an imaging confirmed VTE from January 2011 to November 2016 at our institution. Eligible AYAO participants without a history of VTE were designated as controls and were randomly selected from our institution's tumor registry. Demographics, medical history, surgeries, central venous catheter (CVC) data, VTE diagnosis and treatment, relapses, and deaths were abstracted.

RESULTS

Thirty-five VTE cases and 70 controls were included in this analysis. Eighty percent of cases had leukemia or lymphoma (vs. a solid tumor) compared to 58% of controls. The majority of VTEs (57%) were CVC associated, and more than 70% of cases had more than one CVC placed during their cancer treatment versus 34% of controls. Infection was associated with increased VTE risk (OR = 6.35, 95% CI = 2.30, 17.55, p < .0001). VTE cases had increased cancer relapse (23% vs. 10%) and mortality rates (29% vs. 16%) than controls.

CONCLUSION

AYAO participants with a VTE were more likely to have leukemia or lymphoma, more than one CVC or infection. Further studies are needed to identify patients who would benefit from modifiable prevention measures, such as limiting to one CVC, preventing infections, or considering prophylactic anticoagulation for those with a liquid tumor.

Venous thromboembolism in children with central nervous system tumors: Comparison of an institutional cohort to a national administrative database

BACKGROUND

Central nervous system (CNS) tumors are the second most common malignancy of childhood, and published data on venous thromboembolism (VTE) rate and risk factors for these patients are outdated or incomplete. Here, we determine the cumulative incidence and risk factors for VTE in this population.

PROCEDURE

VTE diagnosis and associated clinical risk factors were abstracted and analyzed for two cohorts of children (0-21 years) diagnosed with CNS tumors between January 1, 2010 to September 30, 2018. The first study was a retrospective single institution cohort study. The initial observations were confirmed across multiple pediatric hospitals using the Pediatric Health Information System (PHIS) administrative database.

RESULTS

The single-institution cohort included 338 patients aged 3 days to 20.9 years (median age, 8.6 years); VTE developed in eight (2.4%) patients. The PHIS cohort included 17 634 patients aged from 0 to 21.9 years (median: 9.5 years); VTE developed in 354 (2.0%) patients. Univariate analysis for the single-institution cohort identified central venous catheter (CVC) placement as a risk factor for VTE (odds ratio [OR] 8.40, 95% confidence interval [CI] 1.43-49.41, P = .0186). Multivariable analysis of the PHIS dataset identified CVC placement (OR 1.97, 95% CI 1.57-2.46; P < .0001), obesity (OR 2.96, 95% CI 1.21-7.26; P = .0177), and more than one hospital admission (OR 3.54, 95% CI 2.69-4.64; P < .0001) as significant predictors of VTE. VTE diagnosis was not associated with increased mortality in either cohort.

CONCLUSIONS

The VTE rate in children with CNS tumors is low (2%). CVC placement was identified as a modifiable risk factor in both cohorts.

Incidence and risk factors of venous thrombotic events in pediatric patients with CNS tumors compared with non-CNS cancer: A population-based cohort study

BACKGROUND

Venous thromboembolism (VTE) is a well-recognized complication in pediatric cancer patients. It has been demonstrated that the incidence of VTE in pediatric patients with central nervous system (CNS) tumors is lower than that of patients with other cancers. Risk factors for developing cancer-related thrombosis are numerous and can include patient, disease, or treatment-related influences. The present study was designed to assess the VTE incidence in a pediatric oncology population, and to investigate whether intensity of treatment has similar associated with risk of VTE development in patients with and without CNS tumors.

METHODS

A retrospective population-based cohort study of pediatric oncology patients in Atlantic Canada was conducted. Data collected from medical records included demographics, cancer type, treatment, presence of central venous catheters (CVC), and presence of thrombosis. Treatment intensity was assessed using the intensity of treatment rating scale (ITR-3). Study period was from January 2000 to December 2017. SPSS version 24 was used for statistical analysis.

RESULTS

Of 1262 patients with pediatric cancer, 247 (19.6%) had CNS tumors. VTE occurred in significantly fewer (n = 5, 2%) patients with CNS tumors compared with patients with non-CNS cancers (n = 79, 7.8%) (p = 0.001). The ITR-3 scores did not differ significantly between the CNS and non-CNS groups (p = 0.638). In a multivariate logistic regression analysis, ITR-3 score was associated with VTE (odds ratio [OR]: 1.48, 95% CI: 1.2-1.9), while presence of CNS tumor was protective (OR: 0.26, 95% CI: 0.1-0.6).

CONCLUSIONS

We demonstrate that pediatric patients with CNS tumors experience a significantly lower incidence of VTE compared with patients with non-CNS cancer. An increase in the ITR-3 rating significantly increased the odds of developing VTE.

Risk Factors for the Development of Hospital-Associated Venous Thromboembolism in Adult Patients Admitted to a Children's Hospital

BACKGROUND AND OBJECTIVES

Hospital-associated venous thromboembolism (HA-VTE) is a leading cause of preventable in-hospital mortality in adults. Our objective was to describe HA-VTE and evaluate risk factors for its development in adults admitted to a children's hospital, which has not been previously studied. We also evaluated the performance of commonly used risk assessment tools for HA-VTE.

METHODS

A case-control study was performed at a freestanding children's hospital. Cases of HA-VTE in patients ≥18 years old (2013-2017) and age-matched controls were identified. We extracted patient and HA-VTE characteristics and HA-VTE risk factors on the basis of previous literature. Thrombosis risk assessment was performed retrospectively by using established prospective adult tools (Caprini and Padua scores).

RESULTS

Thirty-nine cases and 78 controls were identified. Upper extremities were the most common site of thrombosis (62%). Comorbid conditions were common (91.5%), and malignancy was more common among case patients than controls (P = .04). The presence of a central venous catheter (P < .01), longer length of stay (P < .01), ICU admission (P = .005), and previous admission within 30 days (P = .01) were more common among case patients when compared with controls. Median Caprini score was higher for case patients (P < .01), whereas median Padua score was similar between groups (P = .08).

CONCLUSIONS

HA-VTE in adults admitted to children's hospitals is an important consideration in a growing high-risk patient population. HA-VTE characteristics in our study were more similar to published data in pediatrics.

The association of mediastinal mass in the formation of thrombi in pediatric patients with non-lymphoblastic lymphomas

BACKGROUND

Children diagnosed with cancer are at a significantly higher risk of developing a thrombotic event (TE) compared with the general population. The rarity of these events makes it difficult to discern the specific risk factors; however, age, sex, presence of central venous lines, inherited thrombophilia, and mediastinal mass may play a role. The primary aim of this study is to identify prognostic characteristics of children diagnosed with non-lymphoblastic lymphomas associated with a greater risk of developing a TE early on in their disease, with an increased focus on mediastinal mass characteristics.

METHODS

Retrospective chart review of pediatric patients diagnosed with non-lymphoblastic lymphoma between 2004 and 2014 at St. Jude Children's Research Hospital.

RESULTS

TE occurred in 8.5% (n = 28/330) of individuals at a median of 21 days from the diagnosis of a non-lymphoblastic lymphoma, with 60% of TEs occurring within 30 days of diagnosis. Of the variables evaluated, only presence of a peripherally inserted central catheter (odds ratio [OR]: 3.14 [95% CI: 1.24-7.98; P = 0.02]) and degree of superior vena cava (SVC) compression of > 25% increased the odds of developing a TE (OR: 2.2 [95% CI: 1.01-4.93; P = 0.048]).

CONCLUSION

Pediatric patients with non-lymphoblastic lymphoma are at increased risk of developing TEs. In contrast to previous studies, the presence of a mediastinal mass alone was not associated with a higher risk of TE, but individuals with a mediastinal mass with 25% or greater degree of SVC compression were more likely to develop a TE. This finding highlights a high-risk group of children who may benefit from prophylactic anticoagulation.

Prevalence and risk factors for venous thromboembolism in children with sickle cell disease: an administrative database study

A hypercoagulable state resulting in increased venous thromboembolism (VTE) has been described in adults with sickle cell disease (SCD), but similar data for children are lacking. The objective of this retrospective cohort study was to describe the rate of VTE and risk factors associated with VTE in children with SCD across tertiary-care children's hospitals in the United States between the years 2009 and 2015. We used the Pediatric Health Information System database to investigate all pediatric patients with SCD admitted to 1 of 48 participating institutions between 1 January 2009 and 30 September 2015. International Classification of Disease, Ninth Edition, Clinical Modification codes were used to identify index thromboembolic events and chronic medical conditions known to be associated with VTE. Billing codes were used to identify central venous line (CVL) placement and pharmaceutical billing codes to identify estrogen containing oral-contraceptive use. Logistic regression analysis was used to study the association among unique patient characteristics, VTE, and death. 10 454 eligible subjects with SCD were identified. Median age (±interquartile range) of study cohort was 10 (±11) years. 181 subjects (1.7%) developed an index venous thromboembolic event during the study period. Median age at VTE diagnosis was 15.9 (±7.4) years. On multivariable logistic regression analysis, CVL placement, chronic renal disease, history of stroke, female sex, length of hospitalization, intensive care unit utilization, and older age were associated with VTE. After adjusting for other variables, VTE was independently associated with death. In summary, VTE can occur in pediatric patients with SCD. CVL placement is a modifiable risk factor for VTE development.

Epidemiology of Lower Extremity Deep Venous Thrombosis in Critically Ill Adolescents

OBJECTIVE

To determine the epidemiology of lower extremity deep venous thrombosis (DVT) in critically ill adolescents, which currently is unclear.

STUDY DESIGN

We performed a multicenter, prospective, cohort study. Adolescents aged 13-17 years who were admitted to 6 pediatric intensive care units and were anticipated to receive cardiopulmonary support for at least 48 hours were eligible, unless they were admitted with DVT or pulmonary embolism or were receiving or anticipated to receive therapeutic anticoagulation. While patients were in the unit, serial sonograms of the lower extremities were performed, then centrally adjudicated. Bayesian statistics were used to leverage the similarities between adults and adolescents.

RESULTS

A total of 88 adolescents were enrolled, from whom 184 lower extremity sonograms were performed. Of these, 9 adolescents developed DVT, with 1 having bilateral DVT. The frequency of DVT was 12.4% (95% credible interval: 6.1%, 20.1%), which ranged from 6.3% to 19.8% with a variability of 41.0% across units. All cases of DVT occurred in adolescents who received invasive mechanical ventilation (frequency: 16.5%; 95% credible interval 8.1%, 26.6%). DVT was associated with femoral central venous catheterization (OR 15.44; 95% credible interval 1.62, 69.05) and severe illness (OR for every 0.1 increase in risk of mortality 3.11; 95% credible interval 1.19, 6.85). DVT appears to be associated with prolonged days on support.

CONCLUSIONS

Our findings highlight the similarities and differences in the epidemiology of DVT between adults and adolescents. They support the conduct and inform the design of a trial of pharmacologic prophylaxis in critically ill adolescents.

Epidemiology of venous thrombosis in children with cancer

There has been an extensive body of research focusing on the epidemiology of thrombosis in adult cancer populations; however, there is significantly less knowledge about thrombosis in paediatric cancer populations. Thrombosis is diagnosed with increasing frequency in children being treated for cancer, and there is an urgent need to increase our understanding of the epidemiology of thrombosis in this population. Currently, there are no guidelines for identification of high-risk groups, prophylaxis or management of thrombotic complications in paediatric cancer patients. We reviewed the available literature regarding the epidemiology, mechanisms, risk factors, prophylaxis and outcomes of thrombosis in children with cancer and identified areas that require further research. The reported incidence of symptomatic venous thromboembolism (VTE) in children with cancer ranges between 2.1% and 16%, while the incidence of asymptomatic events is approximately 40%. Approximately 30% of VTE in this population is associated with central venous lines (CVL). The most common location of VTE is upper and lower extremity deep venous thrombosis (43 to 50% of events, respectively), while 50% of events in ALL patients occur in the central nervous system. Key characteristics that increase the risk of thrombosis include the type of cancer, age of the patient, the presence of a CVL, presence of pulmonary/intra thoracic disease, as well as the type of chemotherapy. Outcomes for paediatric cancer patients with VTE include post-thrombotic syndrome, pulmonary embolism, recurrent thromboembolism, destruction of upper venous system and death. Prospective studies aimed at enabling risk stratification of patients are required to facilitate development of paediatric specific recommendations related to thromboprophylaxis in this population.

Incidence and characteristics of venous thrombotic events in pediatric cancer patients: A 20-year experience in the Maritimes, Canada

OBJECTIVE

Venous thrombotic events (VTE) are a well-recognized complication in pediatric cancer patients. Population-based data on the incidence and characteristics of VTE in all pediatric cancer patients are limited. This information is crucial to identify patients at high risk and design targeted interventions accordingly. The present study was designed to determine the incidence and characteristics of VTE in the pediatric oncology population.

PARTICIPANTS

We conducted a retrospective, population-based, cohort study of patients treated in the Maritimes, Canada between 1995 and 2015.

RESULTS

There were 1210 pediatric hematology/oncology patients from the Maritimes, Canada, treated at the IWK Health Centre between 1995 and 2015. Fifty-eight (4.8%) experienced at least 1 VTE and the majority of patients experienced it within 6 months of cancer diagnosis. The median age of patients who experienced VTE was 10.7 years (SD = 6.0). The most common presenting symptom of thrombosis was central venous line dysfunction, and the most common location for thrombosis was within the upper venous system. We observed that 65.6% of the patients with VTE required >1 central venous catheters (CVC). The presence of a VTE increased the odds of requiring >1 CVC to 3.6 (95% confidence interval: 1.76-7.3).

CONCLUSION

Thus, in this large, population-based study, we present the incidence and characteristics of VTE in the pediatric oncology population and demonstrate the clinical impact of VTE in terms of loss of CVC. Larger, prospective studies are required to confirm these findings and to develop a risk model for managing and preventing VTE in this patient population.

Venous Thromboembolism in Children with Cancer and Blood Disorders

Venous thromboembolism (VTE) in children is multifactorial and most often related to a combination of inherited and acquired thrombophilias. Children with cancer and blood disorders are often at risk for VTE due to disease-related factors such as inflammation and abnormal blood flow and treatment-related factors such as central venous catheters and surgery. We will review risk factors for VTE in children with leukemia, lymphoma, and solid tumors. We will also review risk factors for VTE in children with blood disorders with specific focus on sickle cell anemia and hemophilia. We will present the available evidence and clinical guidelines for prevention and treatment of VTE in these populations.

Prothrombotic Risk Factors and Preventive Strategies in Adolescent Venous Thromboembolism

Venous thromboembolism (VTE) in adolescents is a serious condition that requires prompt recognition and optimal management to prevent mortality and long-term morbidity. Adolescents account for a large proportion of cases of VTE in children. As teenagers transition from childhood to adulthood, they are at risk of developing medical conditions and exposure to risky habits that predispose them to VTE. This review focuses on the variety of risk factors and comorbidities seen in adolescent VTE and takes a quick look into risk-based preventive strategies for primary and secondary prevention.

Treatment of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common pediatric oncologic diagnosis, and advances in its treatment have led to progressive improvements in survival. The 4 main components of therapy are remission induction, consolidation, maintenance, and central nervous system-directed therapy, and usually last 2 to 3 years. Treatment intensity based on risk-based stratification is the cornerstone of treatment. Patients with features of more favorable disease are spared the more toxic effects of chemotherapy, whereas more aggressive regimens are reserved for those with higher-risk disease. Prognosis of relapsed pediatric ALL depends primarily on duration of remission and site of relapse.

Hospital-associated venous thromboembolism in children: incidence and clinical characteristics

OBJECTIVE

To determine incidence and clinical characteristics of hospital-associated venous thromboembolism (VTE) in pediatric patients.

STUDY DESIGN

A retrospective analysis of patients with hospital-associated VTE at the Johns Hopkins Hospital from 1994 to 2009 was performed. Clinical characteristics of patients aged 21 years and younger who developed VTE symptoms after 2 days of hospitalization or <90 days after hospital discharge were examined. International Classification of Diseases, Ninth Revision codes were used to categorize patients with complex chronic medical conditions and trauma.

RESULTS

There were 270 episodes of hospital-associated VTE in 90,485 admissions (rate 30 per 10,000 admissions). Young adults (18-21 years) and adolescents (14-17 years) had significantly increased rates of VTE compared with children (2-9 years) (incidence rate ratio [IRR] 7.7, 95% CI 5.1-12.0; IRR 4.3, 95% CI 2.7-6.8, respectively). A central venous catheter (CVC) was present in 50% of patients, and a surgical procedure was performed in 45% of patients before VTE diagnosis. For patients without a CVC, trauma was the most common admitting diagnosis. CVC-related VTE was diagnosed most frequently in infants (<1 year old) and in patients with malignancy. Renal and cardiac diseases were associated with the highest rates of VTE (51 and 48 per 10,000, respectively). Rates were significantly higher among those with ≥ 4 medical conditions compared with those with 1 medical condition (IRR 4.0, 95% CI 1.4-8.9).

CONCLUSION

Older age and multiple medical conditions were associated with increased rates of hospital-associated VTE. These data can contribute to the design of future clinical trials to prevent hospital-associated VTE in high-risk children.

Length of stay and treatment-related complications are similar in pediatric and AYA patients with bone sarcoma in United States children's hospitals

BACKGROUND

Adolescent and young adult (AYA) cancer patients have been shown to have unique clinical characteristics and inferior outcomes compared to younger patients. More than 2,500 new bone sarcomas are diagnosed yearly in the US, many of whom are AYAs treated at pediatric hospitals. Pediatric providers must understand the impact of increasing age on complications, costs, and outcomes. The study set-out to determine if AYA patients with bone sarcomas have increased healthcare utilization and treatment-related complications as compared to younger patients.

PROCEDURE

Data were obtained from the Pediatric Health Information System for bone sarcoma admissions at 41 US children's hospitals from 2006 to 2010. Patient demographics and morbidities were compared in patients 0-14 and 15-28 years using two sample t-tests, Wilcoxon two sample tests, or chi-squared tests.

RESULTS

We identified 835 pediatric and 562 AYA patients with bone sarcomas. Mean length of stay (LOS) was comparable between age groups (4.6 and 4.8 days, P = 0.46), although AYA patients had greater mean pharmaceutical charges ($18,124 vs. $13,637, P < 0.0001). Common treatment-related complications were similar between groups, with the exceptions that febrile neutropenia admissions were more likely in younger patients, and thrombosis, renal failure, and pain were more common in AYA patients.

CONCLUSIONS

In US children's hospitals, AYA patients with sarcomas do not have prolonged LOS or an increased risk of the most common treatment-related complications as compared to younger patients. Chronic pain appears to be a greater burden in AYA patients, and may account for their higher inpatient pharmaceutical costs.

Current and future management of pediatric venous thromboembolism

Venous thromboembolism (VTE) is an increasingly common complication encountered in tertiary care pediatric settings. The purpose of this review is to summarize the epidemiology, current and emerging pharmacotherapeutic options, and management of this disease. Over 70% of VTE occur in children with chronic diseases. Although they are seen in children of all ages, adolescents are at greatest risk. Pediatric VTE is associated with an increased risk of in-hospital mortality; recurrent VTE and post-thrombotic syndrome are commonly seen in survivors. In recent years, anticoagulation with low molecular weight heparin has emerged as the mainstay of therapy, but compliance is limited by its onerous subcutaneous administration route. New anticoagulants either already approved for use in adults or in the pipeline offer the possibility of improved dose stability and oral routes of administration. Current recommended anticoagulation course durations are derived from very limited case series and cohort data, or extrapolations from adult literature. However, the pathophysiologic underpinnings of pediatric VTE are dissimilar from those seen in adults and are often variable within groups of pediatric patients. Clinical studies and trials in pediatric VTE are underway which will hopefully improve the quality of evidence from which therapeutic guidelines are derived.

Hospital variation in nitric oxide use for premature infants

OBJECTIVE

To describe inter-center hospital variation in inhaled nitric oxide (iNO) administration to infants born prior to 34 weeks' gestation at US children's hospitals.

METHODS

This was a retrospective cohort study using the Pediatric Health Information System to determine the frequency, age at first administration, and length of iNO use among 22 699 consecutive first admissions of unique <34 weeks' gestation infants admitted to 37 children's hospitals from January 1, 2007, through December 31, 2010.

RESULTS

A total of 1644 (7.2%) infants received iNO during their hospitalization, with substantial variation in iNO use between hospitals (range across hospitals: 0.5%-26.2%; P < .001). The age at which iNO was started varied by hospital (mean: 20.0 days; range: 6.0-65.1 days, P < .001), as did the duration of therapy (mean: 13.1 days; range: 1.0-31.1 days; P < .001). Preterm infants who received iNO were less likely to survive (36.3% mortality vs 8.3%; odds ratio: 6.27; P < .001). The association between the use of iNO and mortality persists in propensity score-adjusted analyses controlling for demographic factors and diagnoses associated with the use of iNO (odds ratio: 3.79; P < .0001).

CONCLUSIONS

iNO practice patterns in preterm infants varied widely among institutions. Infants who received iNO were less likely to survive, suggesting that iNO is used in infants already at high risk of death. Adherence to National Institutes of Health consensus guidelines may decrease variation in iNO use.