A case-control study of dietary intake of renal stone patients. I. Preliminary analysis.

The average daily dietary intake of 88 idiopathic renal stone cases and 88 age and sex matched controls was assessed by history using a standardised questionnaire. Statistical analysis was undertaken on the whole group and on male and female subgroups, to establish if there were any significant differences between cases and controls. There were statistically significant differences in dietary intake between the whole group, the female cases and the control group. Male cases showed only a significantly lower intake of thiamine compared to controls. There was little difference between cases and controls intake of iron or multivitamin supplements but vitamin C supplements (greater than 1 g/day) were taken more than twice as frequently by cases than controls. These results suggest that control dietary studies of renal stone patients without regard to their sex may conceal many differences in dietary intake between cases and controls.