Comparison of mortality between respondents and non-respondents in a mail survey.

We conducted a population-based mail survey and prospectively compared mortality between respondents and non-respondents. Age-adjusted mortality rates for all causes were higher among non-respondents than among respondents in both sexes. Age-adjusted rate ratios were 1.50 for males and 1.33 for females. Non-respondents also had, in both sexes, higher mortality for three leading causes of death, namely, cancer, heart diseases and stroke than respondents. In particular, the difference between the two groups was much greater for cardiovascular disease than for cancer. Our results suggested that prospective studies using data from respondents to mail surveys in Japan would have underestimated the mortality for cardiovascular disease.