Absence of nonresponse bias in a study of sport-caught Great Lakes fish consumption and conception failure

We have reported that men's lifetime sport-caught Great Lakes fish consumption was associated with lifetime prevalence of conception delay or failure. Those cross-sectional data were based on responses to a postal questionnaire. The present study was conducted to evaluate whether nonresponse bias could explain the cross-sectional findings.

We conducted telephone interviews with 230 men and 38 women who did not respond to the original survey, and compared these individuals to the original responders with respect to key demographic, behavioral, and reproductive characteristics.

Nonresponders were approximately 1.5 years older at interview, were more likely to be Caucasian, and reported higher incomes than responders. Among men, nonresponders had fished fewer days in the past year (12% reported no fishing, compared to 4. 3% of responders). Almost one half of nonresponders reported no fish consumption in the past year, compared to one quarter of responders. Nonresponders were more likely than responders to have ever conceived a live-born child, had more children, and were less likely to intend to have additional children in the next 5 years. Among both responders and nonresponders there was an increased prevalence of a period of conception failure among men who reported consuming greater quantities of sport-caught Great Lakes fish.

Our study provides support for the cross-sectional analyses presented previously, insofar as nonresponse bias is unlikely to have a major role in the observed association.