Does response bias influence population studies of thyroid disorders?

Area of Science:

• Epidemiology
• Public Health
• Endocrinology

Background:

• Effective iodine fortification programs require monitoring to prevent oversupply or undersupply.
• Selection bias may impact studies assessing iodine status and thyroid disorder prevalence.

Purpose of the Study:

• To investigate the influence of selection bias on prevalence estimates in thyroid epidemiology.
• To assess the impact of nonresponse and participant selection on monitoring iodine fortification programs.

Main Methods:

• Utilized a baseline population (n=3949) from the Study of Health in Pomerania.
• Analyzed response behavior at 5-year follow-up (n=3300) in relation to sociodemographic and thyroid characteristics.
• Compared prevalence estimates between respondents and the source population, and between early and late respondents.

Main Results:

• No significant bias in thyroid-related prevalence estimates after applying response maximization techniques.
• Prevalence estimates were biased when considering only initial participants, particularly for thyroid disorders and positive anti-thyroperoxidase (TPO) levels.
• Adjusting for sociodemographic factors reduced differences between early and late respondents, except for positive anti-TPO levels.

Conclusions:

• Selection bias is a likely factor influencing prevalence data in thyroid epidemiology.
• More rigorous invitation procedures are recommended to mitigate selection bias in these studies.
• Findings have implications for the accurate monitoring of iodine fortification programs.