Selection bias due to non‐response in a health survey among patients with rheumatoid arthritis

Background: Non‐response may lead to bias in health(care)outcomes. Methods: We compared respondents (n=334) to a questionnaire survey among patients with rheumatoid arthritis with non‐respondents (n=68) and determined predictors of (non‐)response. The bias in prevalence estimates of health characteristics and health care use was quantified. Results: Self‐reported pain and health care utilization were the most important predictors of (non‐)response with respondents experiencing pain more often and more often using specific health care services. Bias concerned especially an underestimation of ‘never having pain’ (60%) and ‘no contact with health care services’ (51%). Conclusion: More insight into the phenomenon of non‐response is important to assess disease burden and health care burden more precisely.