The impact of survey nonresponse bias on conclusions drawn from a mammography intervention trial

J Clin Epidemiol. 2003 Sep;56(9):867-73. doi: 10.1016/s0895-4356(03)00061-1.


Background and objective: This study demonstrates the impact of survey nonresponse bias on conclusions from a mammography trial targeting a disadvantaged population.

Methods: The trial randomized 1558 women to three interventions designed to promote repeat mammography: mailed reminder (minimum group); mailed thank-you card, patient newsletters, and reminder (maximum group); and no mailings (control group). The primary outcome, repeat mammogram within 15 months, was assessed from administrative and phone survey data.

Results: Administrative estimates revealed a statistically significant difference of 7% between the maximum and control groups on the primary outcome. Survey estimates (response rate 80%) revealed no significant differences. The differences by data source were traced to a survey nonresponse bias. There was a statistically significant difference of 16% between the maximum and control groups among survey nonrespondents for the primary outcome, but there were no differences among survey respondents.

Conclusion: The findings reiterate that even a low survey nonresponse rate can bias study conclusions and suggest studies targeting disadvantaged populations should avoid relying solely on survey data for outcome analyses.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Breast Neoplasms / diagnosis*
  • Breast Neoplasms / prevention & control
  • Data Interpretation, Statistical
  • Female
  • Health Surveys
  • Humans
  • Mammography*
  • Middle Aged
  • Poverty*
  • Selection Bias
  • Treatment Refusal*