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Epidemiological disaster research: the necessity to include representative samples of the involved disaster workers. Experience from the epidemiological study air disaster Amsterdam-ESADA
  1. Anja C Huizink1,3,
  2. Nynke Smidt1,
  3. Jos W R Twisk1,
  4. Pauline Slottje1,
  5. Tjabe Smid1,3
  1. 1Institute for Research in Extramural Medicine and Department of Public and Occupational Health, VU University Medical Centre, Amsterdam, Netherlands
  2. 2Erasmus Medical Centre, Department of Child and Adolescent Psychiatry, Rotterdam, Netherlands
  3. 3KLM Health Services, Schiphol Airport, Netherlands
  1. Correspondence to:
 Dr A C Huizink
 Erasmus Medical Centre, Department of Child and Adolescent Psychiatry, WK219, PO Box 2060, 3000 CB Rotterdam, Netherlands; a.c.huizink{at}


Objective: To study whether the methods used to select participants in research on prevalence rates of the health effects of exposure to a disaster may cause bias. This study compared background characteristics, disaster exposure, and complaints reported by (1) police officers who participated in an epidemiological study and underwent a medical examination, and (2) police officers who only participated in an epidemiological study.

Design and Setting: In 2000, an epidemiological study was started to investigate the health status among police officers who were involved in assistance work related to the air disaster in Amsterdam: the epidemiological study air disaster Amsterdam (ESADA). These police officers were personally invited to participate in the epidemiological study and were additionally offered a medical examination, providing them with the opportunity to have their health checked by a medical doctor.

Participants: Of the total group of involved police officers who were invited, 834 (70%) participated in the ESADA: 224 (26.9%) only participated in the study, but 610 (73.1%) also underwent the medical examination.

Main results: Police officers who underwent a medical examination significantly more often reported one or more musculoskeletal complaints, skin complaints, general or non-specific complaints, had more often experienced an event with potentially traumatic impact, or had performed one or more potentially traumatic tasks.

Conclusions: The methods of selection of participants are important in research on health effects after disasters and can result in an overestimation of some of the effects, on average, by a factor of 1.5 to 2.

  • selection bias
  • disaster research

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  • Funding: the study was funded by the Ministry of Health, Welfare and Sports, the City of Amsterdam, the Amsterdam-Amstelland regional police force, and KLM Royal Dutch Airlines.

  • Competing Interest: none declared.

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