Abruptly changing patterns of diffusion and use of extracorporeal shock-wave renal lithotripsy

Early diffusion and use of extracorporeal shock-wave lithotripsy (ESWL) was found by a 1986 survey of the first 84 operational renal lithotripters in the United States to be similar to that of other equipment-embodied technologies. Resurvey in 1988 of this cohort of units found that clinical indications for ESWL treatment--stone size and location--expanded greatly. Professional fees for ESWL services remained essentially constant, while technical component charges increased 21.0%. Volume of procedures declined by 19.8% among the most productive units, and by 34.4% among the least productive study units; the previously noted approximate fourfold difference remained unchanged between most and least productive units. ESWL patterns of diffusion were comparable to other equipment-embodied diagnostic technology (magnetic resonance imaging [MRI] and computed tomography [CT]) during the first few years of clinical availability. ESWL growth slowed sooner than that of CT and MRI following their introduction into clinical practice, declining in the fourth to fifth year of use following rapid expansion in the first 2 years of availability. While clinical indications for both ESWL and imaging technologies expanded over time, CT and MRI experienced continued growth beyond that of ESWL at the same points of their respective life cycles. In the market areas of the 84 study units, the use of ESWL declined even with expanded indications for treatment, perhaps due to faster expansion of number of units than growth of clinical indications for treatment.