Differences in urine volume and supersaturation in 2 physician networks

Purpose: We determined whether a network of practices devoted to a broad ra nge of urological care would achieve a decrease in metabolic stone risk com parable to that achieved by a network of similar practices that emphasized kidney stone management as a distinct specialized interest, provided that e ach was given equivalent access to high level urine testing and software su pport. Materials and Methods: Pretreatment and treatment 24-hour urine samples wer e obtained from patients in a large network of practices related by the sha red use of lithotripsy facilities and instruments (group 2) and a contrasti ng network of practices that emphasize stone treatment over other concerns (group 1). All known urine risk factors, including supersaturation, were me asured and calculated. Results: Treatment supersaturation values in group 2 exceeded those in grou p 1. The reason was unpredicted and unexplained but highly consistent lower urine volume in group 2 patients that was present before and persisted dur ing treatment. Group 2 physicians mostly achieved changes in urine volume a nd stone risk factors equivalent to those of group 1 physicians but began w ith higher supersaturation due to lower urine volume. Conclusions: A network of physicians not specialized for stone care may ach ieve a decreased risk equivalent to that of more specialized physicians. In itial patient characteristics may vary significantly in the groups for reas ons that are unknown to date, greatly affecting treatment outcome.