Purpose. To identify core disagreements between pediatric hematologists who would treat children with idiopathic thrombocytopenic purpura (ITP) on initial presentation (“Treaters”) and those who would treat by observation (“Observers”), to determine whether each group’s preferred stance was consistent with each individual’s detailed perceptions, and to identify key variables in each stance. Methods. A decision model was constructed in collaboration with experts, and a detailed questionnaire was presented to a nationally representative committee of 25 pediatric hematologists. A full decision tree was specified for each respondent. Results. Nineteen (76%) experts responded; based on preference for initial treatment, 9 were Treaters and 10 Observers. Of the 30 probability/effectiveness variables, 8—almost all concerning treatment effectiveness—had at least one statistically-significant difference between the 2 groups regarding low, best, or high estimates. To convince Observers that treatment is effective would take a clinical trial with between 39 000 and 87 000 participants; to convince Treaters that treatment is not effective enough, between 97 000 and 114 000 participants. Observers’ calculated numbers needed to treat (NNTs) of about 150 000 are more consistent (P = 0.0023) with their elicited maximum NTTs of about 500. Conclusion. Physicians not specifically trained provided enough data to specify complete individual decision models. From the estimates provided, no practical clinical trial could convince hematologists who would treat children on initial presentation with ITP just to simply observe them or could convince those who would just observe to instead treat with available agents. Perceived burdens could be better characterized, perhaps by including parental perceptions and preferences.
LilleymanJ. Medical nemesis and childhood ITP. Br J Haematol. 2003;123(4):586–9.
2.
BuchananGR. Bleeding signs in children with idiopathic thrombocytopenic purpura. J Pediatr Hematol Oncol. 2003;25(Suppl 1):S42–6.
3.
EdslevPWRosthojSTreutigerIRajantieJZellerBJonssonOG. A clinical score predicting a brief and uneventful course of newly diagnosed idiopathic thrombocytopenic purpura in children. Br J Haematol. 2007;138(4):513–6.
4.
BrennerBGuilburdJNTatarskyIDoronYGoldsherD. Spontaneous intracranial hemorrhage in immune thrombocytopenic purpura. Neurosurgery. 1988;22(4):761–4.
5.
CohenYCDjulbegovicBShamai-LubovitzOMozesB. The bleeding risk and natural history of idiopathic thrombocytopenic purpura in patients with persistent low platelet counts. Arch Intern Med. 2000;160(11):1630–8.
6.
ImbachPKuhneTBlanchetteV. Overview of the State of the Art Expert Meeting of the Intercontinental Childhood ITP Study Group (ICIS). J Pediatr Hematol Oncol. 2003;25(Suppl 1):S1–6.
7.
KuhneT. Investigation and management of newly diagnosed childhood idiopathic thrombocytopenic purpura: problems and proposed solutions. J Pediatr Hematol Oncol. 2003;25(Suppl 1):S24–7.
8.
ButrosLJBusselJB. Intracranial hemorrhage in immune thrombocytopenic purpura: a retrospective analysis. J Pediatr Hematol Oncol. 2003;25(8):660–4.
9.
ZellerBRajantieJHedlund-TreutigerITedgardUWesenbergFJonssonOG. Childhood idiopathic thrombocytopenic purpura in the Nordic countries: Epidemiology and predictors of chronic disease. Acta Paediatr. 2005;94(2):178–84.
10.
BlanchetteVSLukeBAndrewMSommerville-NielsenSBarnardDde VeberB. A prospective, randomized trial of high-dose intravenous immune globulin G therapy, oral prednisone therapy, and no therapy in childhood acute immune thrombocytopenic purpura. J Pediatr. 1993;123(6):989–95.
11.
WattsRG. Idiopathic thrombocytopenic purpura: a 10-year natural history study at the childrens hospital of Alabama. Clin Pediatr (Phila). 2004;43(8):691–702.
12.
ImbachPZimmermanS. Local and cultural aspects of childhood idiopathic thrombocytopenic purpura: a summary of statements from the 12 countries worldwide. J Pediatr Hematol Oncol. 2003;25(Suppl 1):S68–73.
13.
HuninkMGlasziouPSiegelJWeeksJPliskinJElsteinA. Decision Making in Health and Medicine: Integrating Evidence and Values. Cambridge, UK: Cambridge University; 2001.
14.
PhilipsZGinnellyLSculpherMClaxtonKGolderSRiemsmaR. Review of guidelines for good practice in decision-analytic modelling in health technology assessment. Health Technol Assess. 2004;8(36):iii–iv, ix–xi, 1–158.
15.
ClaxtonKSculpherMDrummondbM. A rational framework for decision making by the National Institute For Clinical Excellence (NICE). Lancet. 2002;360(9334):711–5.
16.
MarksMKVadamalayanBEkertHSouthMJ. Intended management of children with acute idiopathic thrombocytopenic purpura: a national survey. J Paediatr Child Health. 2005;41(1–2):52–5.
17.
LaupacisADavidNSackettDL. How should the results of clinical trials be presented to clinicians?Ann Intern Med Suppl. 1992;116(Suppl 3):A12–4.
18.
SaigalSStoskopfBLFeenyDFurlongWBurrowsERosenbaumPL. Differences in preferences for neonatal outcomes among health care professionals, parents, and adolescents. JAMA. 1999;281(21):1991–7.
19.
ThallPFSimonR. A Bayesian approach to establishing sample size and monitoring criteria for phase II clinical trials. Control Clin Trials. 1994;15:463–81.
20.
GarthwaitePHKadaneJBO’HaganA. Statistical methods for eliciting probability distributions. J Am Stat Assoc. 2005;100:680–701.
21.
ThomasEACRossB. On appopriate procedures for combining probability distributions within the same family. J Math Psych. 1980;21:136–52.
22.
GenestCZidekJV. Combining probability distributions: A critique and an annotated bibliography. Stat Sci. 1986;1(1):114–48.
23.
SpiegelhalterDThomasABestNLunnD. WinBUGS User Manual, Version 1.4. Cambidge, UK: MRC Biostatistics Unit; 2002.
24.
The R Project for Statistical Computing. Vienna: Vienna University of Economics and Business; 2009 [cited 2009 July 26, 2009]; Available from: URL: http://www.r-project.org/
VeselySKBuchananGRAdixLGeorgeJNCohenARBlanchetteVS. Self-reported initial management of childhood idiopathic thrombocytopenic purpura: results of a survey of members of the American Society of Pediatric Hematology/Oncology, 2001. J Pediatr Hematol Oncol. 2003;25(2):130–3.
27.
LutzPVillegaFDucassouSEntz-WerleNMichelG. Management of childhood idiopathic thrombocytopenic purpura: a survey of members of the French Society of Pediatric Hematology and Immunology (SHIP). Arch Pediatr. 2007;14(5):444–9.
DownsS. Technical report: Urinary tract infections in febrile infants and young children. The Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement. Pediatrics. 1999;103(4):e54.
30.
LehmannHPHintonRMorelloPSantoliJ. Developmental dysplasia of the hip practice guideline: technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip. Pediatrics. 2000;105(4):E57.
31.
KlaassenRJDoyleJJKrahnMDBlanchetteVSNaglieG. Initial bone marrow aspiration in childhood idiopathic thrombocytopenia: decision analysis. J Pediatr Hematol Oncol. 2001;23(8):511–8.
32.
BasingaPMoreiraJBisoffiZBisigBVan den EndeJ. Why are clinicians reluctant to treat smear-negative tuberculosis? An inquiry about treatment thresholds in Rwanda. Med Decis Making. 2007;27(1):53–60.
33.
MoreiraJBisigBMuwawenimanaPBasingaPBisoffiZHaegemanF. Weighing harm in therapeutic decisions of smear-negative pulmonary tuberculosis. Med Decis Making. 2009;29(3):380–90.
34.
O’BrienSHRitcheyAKSmithKJ. A cost-utility analysis of treatment for acute childhood idiopathic thrombocytopenic purpura (ITP). Pediatr Blood Cancer. 2007;48(2):173–80.
35.
SpiegelhalterDJAbramsKRMylesJP. Bayesian Approaches to Clinical Trials and Health-Care Evaluation. Chichester, UK: Wiley; 2004.
