Anna Font-GonzalezPhD 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 linkageDag van de Gezondheidsstatistieken, 12th September 2013

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?

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

GBA: Municipal Personal Records Database

• Administrative database• Goal: provide data for population statistics• Demographic information

• 1995-2008

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

Difficulty hospitalization register

(1) Hospitalizations lost if a person changes address

LMR

Postal code 1 Postal code 2

X

GBA

Difficulty hospitalization register

Not unique Unique Not unique

(2) Hospitalized persons are not always a unique person

LMR

GBA

Eligible reference population 1995-2005N=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 linkageEKZ/ 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

Practical issues

• Remote access to CBS

• Shared computer

• Outputs

Objective 1: Hospitalizations in CCS

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

Methods: Hospitalization Rates

• Hospitalization rates of CCS vs POPAverage relative hospitalization ratesRates over time

• Poisson regression modelAdjusted for

Gender, year of birth, follow-up time and calendar year

Recurrent events

Methods: Treatment Risk Factor Analysis

• Within CCS• Same Poisson model• Treatment Risk factors:

• Cancer treatments

Results

Average Relative Hospitalization Rates

CCSn

POPn

RHR 95%CI

Outcome

Hospitalizations

All CCS 216 78 2.79 2.40 -3.17

Censoring CCS at recurrence 172 79 2.20 1.93 –2.51

Hospitalization days 840 296 2.84 2.77 –2.92

Hospitalized person 54 39 1.39 1.28 –1.51

Hospitalization Rate Over Time

CCSPOP

Treatment Risk Factors Within CCS

Significant risk factors: 

RHR 95%CI

Radiotherapy to head and/or neck, yes vs no 1.71 1.20-1.89

Radiotherapy to thorax and/or abdomen, yes vs no 1.13 1.05-1.52

Objective 2: Hospitalization-related health problems in CCS hospitalizations

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)

Statistical Analysis

• Longitudinal analysis: CCS vs POP

• Poisson regression model Gender, year of birth and calendar yearRecurrent eventsCensored recurrences

Results

Average Relative Hospitalization Rates

CCSn

POPn RHR 95%CI

Outcome

Neoplasms hospitalizations 269 433 10.7 7.1-16.3

Endocrine disease hospitalizations 74 174 7.3 4.6-11.7

Diseases of the circulatory system hospitalizations

61 300 3.5 2.4-5.1

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

Contributers & Acknowledgement

Leontien Kremer CBSHuib Caron Datamanagers Elske Sieswerda SurvivorsRonald Geskus KiKaHans ReitsmaMarcel DijkgraafHeleen van der PalFloor van LeeuwenRichard Heinen