1. Anna Font-Gonzalez PhD Student Emma Children’s Hospital/Academic Medical Center Amsterdam, The Netherlands Burden of disease in childhood cancer survivors and consequences for the healthcare system: a follow-up study using medical record linkage Dag van de Gezondheidsstatistieken, 12th September 2013

2. Childhood cancer survivors Childhood cancer survivors (CCS): ↑ chronic health conditions Serious outcome of health condition Impact on patients’ daily life Impact on health care system / society  Long term trends of hospitalizations over time?  Hospitalization-related health problems underlying hospitalizations?

3. Objectives Objective 1. To define long term trends of hospitalizations in CCS over time Objective 2. To define hospitalization-related health problems in CCS hospitalizations

4. GBA: Municipal Personal Records Database Administrative database Goal: provide data for population statistics Demographic information 1995-2008

5. LMR: Hospital Discharge Register Administrative register Hospitalization-related health problems: Diagnosis at hospital discharge ICD9-CM Hospitalization registration includes: DoB Gender Postal code at the date of discharge 1995-2005

6. Difficulty hospitalization register  (1) Hospitalizations lost if a person changes address LMR Postal code 1 Postal code 2 X GBA

7. Difficulty hospitalization register Not unique Unique Not unique  (2) Hospitalized persons are not always a unique person LMR GBA

8. Eligible reference population 1995-2005 N=28 255 Unique Reference Population N=26 583(94%) Corresponding year of birth, gender and calendar year (date of 5- year survival) Gender, date of birth and postal code at the date of discharge CCS eligible for linkage EKZ/ AMC cohort N=1564 Dutch Municipal Population Registry (GBA) N=1477 Dutch National Medical Registry (LMR) 1995-2005 Unique CCS N=1382 (88%) BSN Gender, date of birth and postal code Cohort Study Using Record Linkage Excluded: Non-linked to GBA Excluded: Non-unique after 5-year survivor Excluded:Non-unique after matched date 5-year survival

9. Practical issues Remote access to CBS Shared computer Outputs

10. Objective 1: Hospitalizations in CCS

11. Specific Aims For Objective 1: Hospitalizations in CCS To determine: Average Relative Hospitalization Rates of CCS in comparison with the reference population Hospitalization rates of CCS over time in comparison to a reference population Hospitalization characteristics in CCS CCS risk groups for hospitalization

12. Methods: Hospitalization Rates Hospitalization rates of CCS vs POP Average relative hospitalization rates Rates over time Poisson regression model Adjusted for Gender, year of birth, follow-up time and calendar year Recurrent events

13. Methods: Treatment Risk Factor Analysis Within CCS Same Poisson model Treatment Risk factors: Cancer treatments

14. Results

15. Average Relative Hospitalization Rates CCS n POP n RHR95%CI Outcome Hospitalizations All CCS216782.792.40 -3.17 Censoring CCS at recurrence172792.201.93 –2.51 Hospitalization days8402962.842.77 –2.92 Hospitalized person54391.391.28 –1.51

16. Hospitalization Rate Over Time CCS POP

17. Treatment Risk Factors Within CCS Significant risk factors: RHR95%CI Radiotherapy to head and/or neck, yes vs no 1.711.20-1.89 Radiotherapy to thorax and/or abdomen, yes vs no 1.131.05-1.52

18. Objective 2: Hospitalization-related health problems in CCS hospitalizations

19. Specific Aims For Objective 2: Hospitalization-related health problems 1. Average Relative Hospitalization Rate of hospitalization-related health problems in CCS compared with the reference population 2. Hospitalization rates of hospitalization-related health problems over time compared to a reference population within specific disease groups 3. Risk factors for hospitalization-related health problems (within CCS)

20. Statistical Analysis Longitudinal analysis: CCS vs POP Poisson regression model Gender, year of birth and calendar year Recurrent events Censored recurrences

21. Results

22. Average Relative Hospitalization Rates CCS n POP nRHR95%CI Outcome Neoplasms hospitalizations26943310.77.1-16.3 Endocrine disease hospitalizations 741747.34.6-11.7 Diseases of the circulatory system hospitalizations 613003.52.4-5.1

23. Discussion & Conclusion Childhood cancer survivors have an increased hospitalization rate up to 30 years after primary cancer diagnosis Previously described risks in CCS of neoplasms, endocrine and circulatory diseases translate into increased risk of hospitalizations Implications High and long-term burden of health conditions Need for awareness and knowledge among all healthcare professionals Results can inform follow-up strategies and treatment among CCS and new childhood cancer patients

24. Contributers & Acknowledgement Leontien KremerCBS Huib CaronDatamanagers Elske SieswerdaSurvivors Ronald GeskusKiKa Hans Reitsma Marcel Dijkgraaf Heleen van der Pal Floor van Leeuwen Richard Heinen