Monitoring Outcome in Neonatal Thrombocytopenia
Monitoring Outcome in Neonatal Thrombocytopenia
Rationale: Approximately 10% of neonates admitted to neonatal intensive care units develop a
 major hemorrhage. In an attempt to avert this severe complication various preventive measures
 have been implemented. One of these is the transfusion of platelets to premature neonates
 with low platelet counts. However, this practice is not supported by scientific evidence.
 Most neonates with low platelet counts never experience a major bleeding and platelet
 transfusions may carry risks of volume overload or infection. Therefore, it is important to
 treat only those patients that truly benefit from this intervention. We urgently need a
 scientifically based tool to predict which premature neonates are at risk for major bleeding.
 A few prediction models do exist, but these only allow assessment of bleeding risk at
 baseline, and do not correct for changes in clinical status during the admission period. We
 believe that adding this feature to our prediction model will significantly improve our
 ability to predict bleeding. The prediction model will also be helpful in developing
 individualized transfusion guidelines as it helps us to predict which neonates would benefit
 from prophylactic platelet transfusions.

 Main objective: to develop a dynamic prediction model for bleeding in preterm neonates with
 low platelet counts.

 Study design: retrospective observational cohort study.

 Study population: neonates with a gestational age at birth of < 34 weeks admitted to a
 neonatal intensive care unit (NICU), with a thrombocyte count of less than 50x109/L will be
 included.

 Assessments: only data generated through standard care will be collected. This includes
 platelet counts, cerebral ultrasounds, information about bleeding and transfusions, and
 multiple clinical variables.

 Main study endpoint: major bleeding during admission

 Statistical analyses: dynamic prediction model using landmarking.
2. INTRODUCTION AND RATIONALE

 2.1 The relationship between thrombocytopenia and bleeding A complex relation exists between
 thrombocytopenia in preterm neonates and bleeding. This is illustrated by a recent
 observational study that demonstrated that only 9% of neonates with a very low platelet count
 developed major bleeding.(1) Moreover, patients with normal platelet counts bleed quite
 frequently, as evidenced by another study in which 25-38% of the patients with an IVH did not
 have thrombocytopenia.(2,3) Several recent reviews have highlighted that the fact that
 neonatal bleeding and neonatal thrombocytopenia often occur in the same timeframe, does not
 necessarily imply a causal relationship.(4,5) It is difficult to identify the role of
 thrombocytopenia in bleeding, because bleeding is a multifactorial process, and because there
 are a lot of interactions between bleeding, thrombocytopenia and clinical variables.
 Moreover, neonatal platelets appear to be different from adult platelets in many ways, which
 complicates our understanding of the effect of low platelet counts on bleeding risk, or the
 effect of transfusion of (adult) platelets in the neonatal system.(6)

 2.2 potential prognostic variables The most important known risk factor for bleeding is low
 gestational age.(1) In the specific case of IVH, it is thought that the prematurity of the
 brain - which has a highly vascularized germinal matrix that can easily be damaged - is an
 important causal factor. However, several other factors have been associated with an
 increased risk of bleeding, for example low Apgar scores, acidosis, vaginal birth, need for
 mechanical ventilation, disordered coagulation,NEC, DIC, indomethacin or surfactant
 treatment, low oxygen saturation levels, a low Score for Neonatal Acute Physiology (SNAP),
 and many more. But many of these studies have severe limitations such as lack of multivariate
 analysis, unclear selection of controls, small numbers and different study populations. Most
 are also limited to a baseline risk assessment, without a possibility to correct the risk
 assessment as the clinical status of the child changes. Therefore there is no clarity as to
 which factors are really relevant in clinical practice when assessing neonatal bleeding in
 neonates with thrombocytopenia.

 2.3 Current prediction models A few prediction models for neonatal bleeding have been
 published, but to our understanding, none of these is used regularly in clinical
 practice.(7-9) The main disadvantage of these models is that they only allow assessment of
 bleeding risk at baseline, and do not correct for changes in clinical status during the
 admission period. We believe that adding this feature to our prediction model will
 significantly improve our ability to predict bleeding.

 2.4 The MONET study The MONET study is a retrospective, multicenter, observational cohort
 study that assesses risk factors for neonatal bleeding in thrombocytopenic preterm neonates.
 This population is chosen because these are the neonates that are currently being treated
 with prophylactic thrombocyte transfusions. The results of this study will allow us to
 identify neonates within this population that are at high risk of bleeding. These neonates
 may potentially benefit from different treatment strategies. Also, modifiable risk factors
 can be further explored as potential targets for preventing neonatal bleeding.

 3. OBJECTIVE

 To develop a dynamic prediction model for bleeding in preterm neonates with low platelet
 counts.

 4. STUDY DESIGN

 Retrospective observational cohort study. Timeframe in which data will be collected is 5
 years (2010-2014).

 5. STUDY POPULATION

 5.1 Population (base) Neonates will be selected based on inclusion and exclusion criteria
 defined below.

 5.2 Inclusion criteria

 1. Admission to a neonatal intensive care unit (NICU) in the Netherlands, including
 postnatal transfers;

 2. Gestational age at birth < 34 weeks;

 3. A platelet count of <50 x109/L;

 5.3 Exclusion criteria

 A potential subject who meets any of the following criteria will be excluded from
 participation in this study:

 1. Severe congenital malformations;

 2. High suspicion of spurious platelet count (e.g. clots in the sample, or very rapid
 'recovery' to previous non-severely thrombocytopenic levels);

 3. Thrombocytopenia which occurred exclusively in the context of exchange transfusion;

 4. Prior admission to a NICU (only first admissions to NICU's will be included. Postnatal
 transfers from non-NICU's will be included).

 5.4 Sample size calculation Data on the frequency of bleeding outcomes in severely
 thrombocytopenic neonates are available from the PlaNeT-1 survey in which 15/169 or 9% of
 neonates experienced a major bleed while on study.(1) However, this proportion applies to
 neonates of all gestational ages. Other studies show incidences in premature neonates of
 7-11%, depending on the type of population studied.(3,10,11) Assuming an event rate of
 approximately 10%, we calculated that for testing 5 variables we will need a sample size of
 500 neonates, because we will need approximately 10 events per tested variable. Each year,
 4000 neonates are admitted to the neonatal intensive care unit, of which approximately 5%
 have severe thrombocytopenia. Therefore, we expect 200 eligible neonates each year, and a
 total sample size of 1000 neonates, which will allow us to include a maximum of 10 variables.

 6. METHODS

 6.1 Main study endpoint

 Major or severe bleeding during admission is the primary outcome. This has been defined as
 either one of the following:

 1. Intraventricular hemorrhage grade 3 (>50% of ventricle filled with blood)

 2. Intraventricular hemorrhage of any grade in combination with parenchymal involvement.
 Information about dimensions will be collected: maximum diameter of <1 cm, or 1-2 cm or
 >2 cm.

 3. Parenchymal hemorrhage (without IVH) visible on ultrasound (contrary to small bleeds
 visible only on MRI). Information about size will be collected: maximum diameter <1 cm,
 1-2 cm or >2 cm.

 4. Cerebellar hemorrhage visible on ultrasound (contrary to small bleeds visible only on
 MRI). The maximum diameter of the bleeding will be collected.

 5. Other types of intracranial hemorrhage. The maximum diameter will be recorded.

 6. Pulmonary hemorrhage, defined as fresh blood from the endotracheal tube in combination
 with increased ventilatory requirements

 7. Any other type of hemorrhage, if major. A bleeding was considered major if it required
 or was related to either one of the following:

 1. Red cell transfusion

 2. Volume boluses

 3. Need for inotropes (either start of inotrope therapy, or increased dose of current
 therapy)

 4. Significant drop in blood pressure The first time a major bleed was diagnosed is
 the endpoint for this study. Date and time of first major bleed will be recorded,
 if the exact time cannot be retrieved from the medical file, an estimate will be
 computed based on what is known about the timing (for example, that it occurred in
 an evening shift, or that it occurred after 16:00).

 6.2 Clinical variables The initial strategy was to select clinical variables
 through a systematic review of the literature in combination with expert advice.
 The review was started, but yielded over 8000 abstracts, and over 1000 included
 full texts, and was therefore considered too large for the scope of this project.
 However, an overview of the clinical variables assessed in these papers was made,
 and will be taken into account during the variable selection process. Clinical
 variables will be selected based on literature in combination with expert advice.
 Exclusion of a variable will be considered when the variable is not not
 consistently documented in medical records, when few studies concerning this
 variable have been published, when multiple published studies show a weak
 association with bleeding, when a strong interaction with another variable is
 expected (e.g. birth weight and IUGR), or when the variable is difficult to measure
 regularly (e.g. blood parameters that need large blood samples).

 6.3 study procedures Data will be collected by study personnel, including research
 nurses, datamanagers and medical students under supervision of the principal
 investigator. Data will be collected from the hospital's written or online patient
 record files, recorded imaging reports and nurses records. Data collection ends
 when a neonate is transferred out of the neonatal intensive care unit, when a major
 bleed occurs, or when a neonate dies.

 7. SAFETY REPORTING

 MONET is an observational study, therefore we consider reporting of adverse events
 or serious adverse events not applicable for this study.

 8. STATISTICAL ANALYSIS

 The development of the prediction model will take place in cooperation with several
 experts, including prof. dr. J.G. van der Bom, professor in clinical transfusion
 medicine, and prof dr. H. Putter, professor of medical statistics and an expert in
 dynamic prediction modelling. We will develop a dynamic prediction model using
 landmarking, as described elsewhere.(12) A statistical analysis plan will be
 written and signed prior to any analysis. Variables to be included in the model
 will be chosen prior to the statistical analyses.

 9. ETHICAL CONSIDERATIONS

 9.1 Regulation statement This study will be conducted according to the principles
 of the Declaration of Helsinki (version 59, oct 2008). The Medical Research
 Involving Human Subjects Act (WMO) does not apply.

 9.2 Recruitment and consent Informed consent does not need to be obtained for this
 study, as only retrospective data are being collected.

 10. ADMINISTRATIVE ASPECTS, MONITORING AND PUBLICATION

 10.1 Handling and storage of data and documents Data will be held and processed in
 accordance with the Dutch Personal Data Protection Act. All study data will be held
 securely. It will not be disclosed to third parties. All staff working on the study
 owe a duty of confidentiality to the participants. Manual records will be held
 securely (for example in locked filing cabinets). Electronic records will be held
 on a secure network requiring user ID and password access. A fully anonymised data
 set will be used for data analysis. Individuals will not be identifiable from the
 results of the study. Neonates enrolled in the MONET study will receive a unique
 study code. Data will be send to the study manager and entered into a MONET
 database.

 10.2 Monitoring and Quality Assurance Because of the retrospective, observational
 nature of this study, monitoring was not deemed necessary.

 10.3 Public disclosure and publication policy The study will be registered in the
 website of the Dutch National Competent Authority, the 'Centrale Commissie
 Mensgebonden Onderzoek' (CCMO) and a public study registry. The results from the
 MONET study will be analyzed and published as soon as possible in peer-reviewed
 international scientific journals and presented at scientific meetings, unless the
 study was terminated prematurely and did not yield sufficient data for a
 publication. The responsibility for presentations and/or publications belongs to
 the investigators. No restriction regarding the public disclosure and publication
 of the research data have been, or will be made by the funding agencies. The final
 publication of the study results will be written by the principal investigators and
 the co-investigators. A draft manuscript will be submitted for review to all
 co-authors. Results will also be published in a PhD-thesis. Authors of the main
 manuscript will include the Principal Investigator, the co-investigators and,
 investigators who have included evaluable patients in the study. Others who have
 made a significant contribution to the study may also be included as author, or
 otherwise will be included in the acknowledgement.

 11. REFERENCES

 1. Stanworth SJ, Clarke P, Watts T, Ballard S, Choo L, Morris T, et al.
 Prospective, observational study of outcomes in neonates with severe
 thrombocytopenia. Pediatrics [Internet]. 2009 Nov [cited 2013 May
 27];124(5):e826-34. Available from:
 http://www.ncbi.nlm.nih.gov/pubmed/19841111

 2. von Lindern JS, Hulzebos C V, Bos AF, Brand A, Walther FJ, Lopriore E.
 Thrombocytopaenia and intraventricular haemorrhage in very premature infants:
 a tale of two cities. Arch Dis Child Fetal Neonatal Ed [Internet]. 2012 Sep
 [cited 2014 Oct 1];97(5):F348-52. Available from:
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 neonates and the risk of intraventricular hemorrhage: a retrospective cohort
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 12. APPENDIX 1: names and contact information of participating NICUs

 NICU University Medical Center Groningen (UMCG) Local investigator: Chris Hulzebos,
 neonatologist

 c.v.hulzebos@umcg.nl

 NICU Isala Klinieken Zwolle (Isala) Local investigator: Esther d'Haens, neonatologist
 e.j.haens@isala.nl

 NICU University Medical Center Utrecht (UMCU) Local investigator: Daniël Vijlbrief,
 neonatologist d.c.Vijlbrief@umcutrecht.nl

 NICU Academic Medical Center Amsterdam (AMC) Wes Onland, neonatologist
 w.onland@amc.uva.nl

 NICU Leiden University Medical Center (LUMC) Local investigator: Enrico Lopriore,
 neonatologist e.lopriore@lumc.nl

 NICU Maxima Medical Center Veldhoven (MMC) Peter Andriessen, neonatologist
 p.andriessen@mmc.nl

 NICU Erasmus University Medical Center Rotterdam (Erasmus MC) Andre Kroon, neonatologist

 a.a.kroon@erasmusmc.nl
Inclusion Criteria:

 -  gestational age <34 weeks at birth

 -  platelet count <50x10^9/L

 Exclusion Criteria:

 -  readmission to NICU (only first admissions are included. Postnatal transfers from
 non-NICU hospitals are included)

 -  major congenital malformations

 -  high suspicion of spurious platelet count

 -  thrombocytopenia exclusively in the context of exchange transfusion