Is SWL safe and effective? Good research is lacking

Recent studies of potential deleterious effects of SWL demonstrate that these questions did not go away. A large retrospective review from the Mayo Clinic reported in 2006 suggested a potentially higher incidence of hypertension and diabetes after SWL. At this year's AUA annual meeting, four groups reviewed their own databases to determine whether they could answer this question (see, "Multiple studies support safety of ESWL," page 1). Three of the four studies found no increase in hypertension or diabetes after treatment. But one study out of Canada suggested a possible increased incidence of hypertension, although the authors specifically noted that there did not appear to be a cause-and-effect relationship between SWL treatment and increased blood pressure.

While these data may help to allay concerns, all of these studies have been retrospective in nature. To date, there have been no long-term prospective trials in which all patients are enrolled, undergo identical testing at the same institution, and are closely followed for a number of years. Many of the recent retrospective reviews were performed by patient questionnaire. So while these investigations raise concern about a relationship between SWL and diabetes or hypertension, the data are still lacking.

Finally, we need to better educate physicians about SWL and its potential deleterious effects. The jury is still out as to whether SWL increases the risk of diabetes or hypertension. All would agree, however, that excessive treatment can cause renal damage and may lead to clinical problems. By being more cognizant of potential problems and by selecting appropriate stones and patients for shock wave management, we can not only improve outcomes, but also minimize adverse effects.

In addition, by establishing a large SWL registry to track patients over time, we can better define whether there is a problem and, by using newer technologies and techniques, we can make lithotripsy as safe as possible.

Shock wave lithotripsy is still a marvelous advance in our management of stones, and it is still a highly effective and safe way to treat patients, but it's not for everybody. We have to use this technology judiciously and perform additional studies to better define the best treatment for each patient and how we can minimize tissue injury and maximize outcomes.