Recent claims-based analyses of health care utilization,
particularly in the inpatient setting, have suggested a
narrowing of the risk difference for stone disease between
men and women [2,3]. Our data show that the overall
prevalence of stone disease is 10.6% in males and 7.1% in
females. At least two potential explanations exist for these
apparently contradictory findings. First, these different
findings could represent gender-based practice variation;
that is, for reasons that are not illuminated by these data,
men may be less likely to be treated as inpatients for stone
disease. Alternately, our data are potentially consistent with
the hypothesis that in the past, men were much more likely
to form stones (represented by the large difference in
prevalence between males and females aged 50 yr), but
risks are currently more equal, as represented by the very
similar prevalence of stone disease among males and
females aged 20–49 yr. Because of the cross-sectional
nature of the NHANES dataset, it is difficult to conclusively
test this hypothesis. The NHANES dataset is specifically
designed to estimate the prevalence of conditions in the US
population and should be considered more reliable than
claims-based utilization data for addressing questions of
disease prevalence.