Recurrence of nephrolithiasis. A six-year prospective study.

Retrospective studies of nephrolithiasis tend to overestimate the severity of the disease and mistakenly ascribe benefits to treatment regimens. The results of a three-year study of recurrent nephrolithiasis in three patient groups adhering to a calcium-restricted diet who were treated with phosphate therapy, placebo or diet alone are re-examined at the close of an additional three-year follow-up period. Nearly half the subjects in all groups remained free of stone for the six-year period. A reduction in the need for lithotomies occurred in all groups. The absence of renal calcification at entry into the study as well as increasing age were associated with a marked reduction in stone passage. Drug therapy should probably be avoided in older patients as well as in those who are free of renal calcifications.