Prevalence Rate of Renal Stone Disease in Forsyth County, North Carolina During 1977

A count of all recorded hospitalized cases of Forsyth County, North Carolina residents with a primary discharge diagnosis of renal (kidneyand/or ureteral) stone in 1977 is obtained by age, race and sex, and used in conjunction with the census data to estimate age-adjusted prevalence rates. The over-all prevalence rate is 2.08 per thousand population, which agrees well with results of earlier investigations. For white male subjects the age-adjusted prevalence rate is 3.64 per thousand, for white female subjects 1.44, for non-white male subjects 0.97 and for non-white female subjects 0.34. The white to non-white ratio and the male to female rates are compared with earlier published values. For all groups the prevalence rate increases with age, attaining a maximum in the 40 to 60-year category for whites and somewhat later for non-whites. Beyond age 60 prevalence drops, reaching 0 or near 0 in the 80 to 89-year range. A simple phenomenological model is suggested to explain the observed race and sex differences in the prevalence rates.