Healthy Skepticism Library item: 3932

Warning: This library includes all items relevant to health product marketing that we are aware of regardless of quality. Often we do not agree with all or part of the contents.

Publication type: news

Altman L.
Blasting of Kidney Stones Has Risks, Study Reports
New York Times 2006 Apr 9
http://www.nytimes.com/glogin?URI=http://www.nytimes.com/2006/04/10/health/10kidney.html&OQ=_rQ3D1&OP=102e21b6Q2FQ5BF6WQ5BQ3AQ5Ep5fQ5EQ5En,Q5B,((UQ5B(Q2AQ5B9(Q5Bd6hsndQ5B9(Q27Q24Q3Ai6zQ51dngs

Keywords:
lithotripsy

Notes:

Ralph Faggotter’s Comments:

This article is interesting in that it never presents a reason as to why the kidney stones should be removed in the first place.

Most kidney stones sit there harmlessly, occasionally one will move down the ureter ( which is extremely painful) but it then comes out and the problem settles. Recurrent urinary tract infections are sometimes a problem.

So why utilize an expensive technology to break up an asymptomatic kidney stone and risk serious consequences?

Is the widespread use of lithotripsy a case of ‘Boys with Toys’? Or ‘treating the xray’ and not the patient? Or engaging in a risky but necessary procedure?

Due to the expense of purchasing a lithotripser, there will naturally be a certain financial pressure on the urologist/health care corporation to get a return on his/her investment by over-using the technology.

Is the widespread use of the lithotripser a case of ‘selling sickness’?

Full text:

Blasting of Kidney Stones Has Risks, Study Reports
By LAWRENCE K. ALTMAN
WASHINGTON, April 9 – The use of shock waves to pulverize kidney stones into sand-like material significantly increases the risk for diabetes and high blood pressure later in life, according to the longest follow-up study of the popular therapy.

In the study, which is to be published on Monday from the Mayo Clinic, patients who underwent the pulverizing procedure, known as lithotripsy, developed diabetes at almost four times the rate of those whose kidney stones were treated by other methods. The lithotripsy group also developed high blood pressure about 50 percent more often than a group treated by other methods, the study in The Journal of Urology found.

The diabetes risk was related in part to the number of shocks given, said the Mayo Clinic researchers in Rochester, Minn. The risk for high blood pressure, also known as hypertension, was related to treatment of stones in both kidneys but not to the total number of shocks, which can number in the hundreds or thousands.

The Mayo Clinic issued a news release saying that its researchers are “sounding an alert about the side effects of shock wave lithotripsy” and that the findings are “completely new.”

The findings also were surprising because earlier studies had not identified diabetes as a complication of the procedure, said Dr. Amy Krambeck, a co-author of the study. There have been conflicting findings about hypertension as a complication.

Dr. Krambeck said her team wanted to find an animal model to determine precisely how the shock waves caused diabetes and hypertension.

For now, the Mayo researchers hypothesize that shock wave therapy for kidney stones increases the risk for diabetes by damaging the insulin-producing cells in the pancreas, a gland through which the shock waves may pass. They also theorize that shock waves may increase the risk for hypertension by scarring the kidneys and affecting their secretion of hormones, like renin, that can influence blood pressure.

The findings of the new study underscore the importance of following patients many years after they receive new therapies and how rarely studies do so because of costs and long-term research interest. Because the new findings were based on a follow-up of the first year that lithotripsy was used at the Mayo Clinic, in 1985, confirmatory studies from other medical centers are needed, Dr. Krambeck said.

Lithotripsy still has an important role in treating kidney stones despite the risks her team found, Dr. Krambeck said in a telephone interview.

About 10 percent of men and 5 percent of women aged 70 and younger develop a kidney stone, according to the National Institutes of Health, a federal agency in Bethesda, Md. Kidney stones can occur as an isolated medical event, but often are part of a systemic biochemical disorder.

An estimated one million people in the United States have undergone lithotripsy treatment since the German-developed procedure was introduced in this country in 1984. Shock waves demolish up to 90 percent of kidney stones.

Patients considering lithotripsy should be informed about the new findings, said Dr. Dean G. Assimos, vice chairman of the urology department at the Wake Forest University School of Medicine in Winston-Salem, N.C.

“But based on this article, urologists can’t say patients shouldn’t have lithotripsy” because “overall, lithotripsy is a great technological advance that has helped thousands of patients,” Dr. Assimos said in a telephone interview. He is also vice chairman of the American Urological Association’s committee that issues guidelines on kidney stone therapy.

Stones in the kidneys and urinary tract system can be treated by a variety of other techniques that have improved during the 25 years that lithotripsy has been used. One way is to insert an instrument through an incision in the patient’s back to remove the stone. Another is to insert a tube into the urethral opening, into the bladder and into the ureter to break up a stone with ultrasound or laser energy.

Unlike lithotripsy, these procedures are invasive, often require a longer hospital stay, and have their own risks like bleeding, infection and injury to the bladder or ureter.

So kidney stone patients, like those with many other conditions, face a trade-off in evaluating the relative risks of available treatments.

Lithotripters were a landmark advance when they were introduced in the early 1980’s because they greatly lessened the need for what was then the main therapy – surgery – that often required general anesthesia and a lengthy recuperation. Shock wave treatment can be performed with quickly reversible intravenous sedation and avoids long convalescence. Although lithotripsy can cause acute problems like bleeding in and around the kidneys, doctors have considered it safe over the long run.

Dr. Krambeck said that as a urologist-in-training she brought a fresh outlook on the long-term complications of lithotripsy. She and her colleagues decided that a new study would be worthwhile because of the limited number of studies, the longest seven years.

One short-term study found a higher risk for hypertension but two did not, she said, and no study identified diabetes as a long-term risk.

To scientists, the studies with greatest validity are those that are conducted prospectively – establishing a scientific blueprint before they begin to collect information and then following patients and analyzing the data later. But because there was no such continuing long-term study for lithotripsy, and starting one would take years and be costly, the Mayo researchers did the next best thing: a retrospective case control study, even though that study design limits interpretations of the findings.

Dr. Krambeck’s team sent questionnaires to the survivors among the first group treated with a lithotripter machine at the Mayo Clinic in 1985. For comparison, the researchers did the same for a group of patients who received different therapy at the clinic in the same year.

In each group, 288 patients responded. Of these, 48, or 16.8 percent, in the lithotripsy group developed diabetes, compared with 19, or 6.7 percent, in the control group. High blood pressure developed in 103, or 36.4 percent, of the shock-treated group compared with 79, or 27.9 percent, in the control group.

Dr. Krambeck’s team did not analyze certain risk factors, like a family history, for diabetes, but Dr. Assimos, the Wake Forest expert, said that “they did as good a job as they could do with a retrospective study.”

The study took about one year to complete. In May, the Mayo team sent its paper to The Journal of the American Medical Association, which rejected it without sending it to independent experts for review, saying it was too specific a topic for its readers, Dr. Krambeck said.

So her team then sent the paper to The Journal of Urology. In September, after the Mayo doctors made requested revisions, the journal accepted it, she said.

Last August, the Mayo team presented its findings at an international meeting, Dr. Krambeck said, but for a number of reasons the clinic did not issue an alert for the thousands of people considering lithotripsy.

Her team did not want to release the findings early because the Mayo Clinic is one of a very few medical centers that still uses the same model lithotripter, Dornier HM3, in use in 1985, she said. Over the years, manufacturers have developed newer model machines that narrow the range of shock waves but that break up fewer stones. Because most urologists use the newer models, Dr. Krambeck said, “we can’t say that every lithotripter causes” the diabetes and hypertension complications.

Another reason for not issuing an earlier alert is that many journals impose strict embargoes on releasing information in papers before publication. Journals have withdrawn papers because authors released information to the public beforehand.

“The journal did not want us to discuss the paper until the embargo was lifted, of course,” Dr. Krambeck said.

Dr. Assimos of Wake Forest defended the delay as “appropriate.”

Mayo urologists discuss all alternatives for treating kidney stones with patients but use lithotripsy less than other procedures, Dr. Krambeck said. After learning the results of their study, the doctors began informing patients who were considering lithotripsy about “correlations with possible side effects” but without specifying which ones or the data, she said. Now they will provide that information.