Recurrence rates and severity of urinary calculi.

During the last ten years, data of urinary calculi was received in 4094 cases on the criterion of "recurrence", whereby the answer was "yes" in 1446 cases. The overall "adjusted relative recurrence rate" (ARRR) is therefore 35.3%. The importance of an exact physical analysis of urinary stones, involving a differentiation of the various Ca oxalates and Ca phosphates, becomes clear looking at the high recurrence rates for the monomineralic stones of the Ca stone class like brushite and weddellite (ARRR = 66.7% and 50.0%, respectively) compared to apatite and whewellite (ARRR = 36.5% and 29.2%, respectively). Dramatic changes in the composition of the recurrent stone were observed only in 12.7% of all cases. The highest ARRR was found in infection stones with a large content of struvite (about 75%), whereas the total recurrence rate of the infection stone class was about 38%. An assessment of the "danger" of a urinary stone taking into account the criteria of "composition" and "prevalence to recur" is given.