Ask any casual reader of the AHCPR Guideline "How does Electrical Stimulation compare with Biofeedback as a treatment for Urinary Incontinence", and you are likely to hear something like this: "Estim is very close to Biofeedback in effectiveness -- 77 percent compared with 82 percent improvement. It's almost a tie!"
But is it? In fact, Estim isn't even close to Biofeedback in effectiveness, but it takes more than a casual reading to discover the truth. Incredibly, most of the evidence for this statement is reproduced within the Guideline document itself. But a little outside searching is required to see the most damning evidence. Some of that will be presented below.
Back in the early 1980s, a brilliant young psychologist named Kathy Burgio, PhD spent five years working for the National Institute on Aging. Her assignment was to take the ano-rectal manometry systems that Schuster and Engel had developed for treating fecal incontience by biofeedback and apply this technology to the treatment of urinary incontinence. In a series of well-conceived and executed studies resulting in several published papers, she demonstrated that the biofeedback could drastically reduce incidents of urinary incontinence -- without the side effects and dangers of drugs or surgery.
Burgio consistently reported her results in terms of the percentage reduction in "accidents", both for individuals and for experimental vs. control groups. In general, she achieved an 80-95 percent reduction, with an average symptom reduction of around 85%. In addition, she published detailed data that showed about 29% of her patients were actually "cured" -- i.e., 100% reduction in wetting accidents. Most biofeedback researchers followed her good example in reporting "percentage reduction in accidents" in their research.
But when large American medical companies began manufacturing electrical stimulation devices to cash in on the emerging multi-billion dollar incontinence market, they were faced with a dilemma -- their Estim results were considerably less impressive than Burgio's biofeedback results. So, to make their "clinical trials" look more impressive, they began to report on not accidents -- but people.
One of the first, for instance, was a privately published essay "Transvaginal Electrical Stimulation for Incontinence", written by Peter K. Sand, MD, and John S. Wheeler, MD, at Rush-Presbyterian-St. Luke's Medical Center in Chicago. In their abstract they boasted that 81% of their 48 subjects "reported improvement", and that 85% of them would "recommend the therapy to their peers". ["Recommend" is a curious scientific category. And we do wonder why 4%, or two women who did not show any improvement at all, would nevertheless want to inflict Estim on their peers.]
The authors further report that for stress incontinent women (n=14) there was a significant reduction in leakage (pad test: an average of 24 grams before, an average of 5 grams after), and for all subjects, a statistically significant increase in pelvic floor (muscle) strength, from 12 mm H2O to 16 mm H2O. Unfortunately there is no mention of Burgio's percent reduction of "accidents" out in the real world, and apparently no one was actually "cured" or they would surely have mentioned it. We are only told that 81% "overwhelmingly claimed improvement in their incontinence" [How's that for objective writing?]
There are two other major problems with this study. First, there is no mention of the actual instructions given to the subject regarding the use or non-use of pelvic muscle exercises during stimulation. The Guideline mentions that in most stim research, subjects are also advised to do PME when they feel the stimulator. This, of course, totally contaminates the experimental condition, since we don't know how much of the improvement came from the PME and how much came from the Estim device. In this study 81% of the subjects showed "some" (i.e., "any") improvement; even as little as 5% reduction in accidents was called an "improvement". That is in line with the results for "plain" Pelvic Muscle Exercise anyway, so it is questionable if the stimulator was responsible for any of the improvement. [Recall that Wells, Brink, Diokno, et al, 1991, found 77% of their plain PME subjects got "some improvement", so the Estim device contributed only 4% (n=2) subjects who reported (any) "improvement".] And remember, we are not talking about symptom reduction, only about patients who "improved" at all.
The second major flaw is a very difficult one to overcome. All of the subjects received two "muscle evaluation" sessions with a portable biofeedback device. This was done, quite appropriately, to see if their muscles actually improved as a result of their participation in the experiment. Unfortunately, it also means that the Estim condition was contaminated by a biofeedback training session, which may have contributed substantially to their tiny (4 mm H2O) improvement in strength.
Recall that Jacques Susset, MD, using the very same air-pressure biofeedback device for both evaluation and training, obtained a 54 mm H2O increase! (His patients went from 18 mm H2O before therapy to 72 mm H2O after biofeedback therapy.) In other words, the same manufacturer's biofeedback device resulted in muscle improvement 13 1/2 times greater than his electrical stimulator device did. In addition, 80% of Susset's patients were completely cured, whereas no claim for cure is offered for any of Sand's Estim patients.
Obviously the authors, who are all learned men, were acutely aware of the limitations of this very preliminary study, and they sought to correct their mistakes in later research for this and other manufacturers. Their lack of success will be discussed below, in line with the Guideline's statements on Electrical Stimulation.
Underscores are added to the text below to highlight important words and exceptions.
Pelvic Floor Electrical Stimulation
Pelvic floor electrical stimulation has been shown to decrease incontinence in women with SUI. (Strength of Evidence B.)
Pelvic floor electrical stimulation may be useful for urge and mixed incontinence. (Strength of Evidence B.)
Curiously, this is a reversal of the commonly accepted wisdom on the subject, which holds that electrical stimulation may have some value in URGE incontinence, but is relatively without merit in treating STRESS incontinence. The reason for this view is that stimulation does trigger the inhibitory reflex that quiets the premature bladder contractions of Urge, but does little to strengthen the weak muscles of Stress Incontinence.
Pelvic floor electric stimulation (nonimplantable) produces a contraction of the levator ani, external urethral and anal sphincters, accompanied by a reflex inhibition of the detrusor: this activity depends on a preserved reflex arc through the sacral micturition center (Vodusek, Plevnik, Vrtacnik, et al., 1988). Nonimplantable pelvic floor electrical stimulation uses vaginal or anal sensors or surface electrodes (Vodusek, Plevnik, Vrtacnik, et al., 1988). Adverse reactions are minimal and include pain and discomfort.
Minimal? Depends whose ox is being gored, as the expression goes. Various studies report up to 20-40 percent of subjects complain of irritation, with many "drop-outs" due to the discomfort of Estim. See below.
Studies vary regarding the type and placement of electrodes; frequency, duration, and amplitude of voltage; and whether the stimulation was phasic, intermittent, or continuous.
Actually every new manufacturer has tried to come up with an "improved" pattern of stimulation which will be superior to all the others. So far, no one pattern stands out as being better than the others.
Several of these studies address long-term follow-up with reports that the effects for cured or improved patients ranged from 54 to 77 percent (Bent. Sand, Ostergard, et al., 1993: Berginann and Eriksen. 1986: Blowman. Pickles, Emery, et al., 1991; Caputo, Bensen. McClellan. et al., 1993: Eriksen, 1990: Eriksen, Bergmann, and Mjolnerod 1987; Eriksen, Bergmann, and EikNes. 1989: Esa, Kiwamoto, Sugiyama. et al., 1991; Fall. Ahlstrom, Carlsson. et al.. 1986: Fossberg, Sorensen, Ruutu, et al 1990: Green and Laycock. 1990: Hahn, Sommar, and Fall, 1991; Lamhut, Jackson, and Wall, 1992; Leach and Bavendam, 1989; Lose, Andersen, and Kristensen, 1986: Mcintosh, Frahm. Mallett. et al., 1993: Meyer. Dhenin, Schmidt, et al., 1992; Eriksen and Mjolnerod, 1987; Nakamura. Sakurai, Tsujimoto. et al., 1986; Nakamura, Sakurai. Sugao, et al., 1987; Ohlsson. Fall. and Frankenberg-Sommar. 1989; Plevnik, Joney, Vrtacnik, et al., 1986: Sand, Richardson, Staskin, et al, 1995; Wilson. 1990: Zollner-Nielsen and Samuelsson. 1992).
This statement is quite misleading, especially coming as it does only one page after the biofeedback section, where the "percents" refer to reduction in symptoms, not the percent of patients having improvement in symptoms. Sand, Richardson, Staskin, et al, 1995, for example, listed above, in response to criticism, starting defining "improved" as having a "50% or greater reduction in pad weights" (and only 62% of their patients achieved even that modest goal).
Consider for a moment how little a 50% reduction really is. If a patient is using six adult diapers a day (not uncommon), she will be using only three diapers a day after 15 weeks of twice-daily Estim (210 practice sessions). That's 21 diapers a week, or 1,092 diapers a year for the rest of her life! If your mechanic fixed your engine so that instead of burning a quart of oil every 100 miles it burned a quart every 200 miles, would you consider the car to be properly "fixed"?
Two randomized controlled trials have been conducted. Using active and placebo perianal surface patch neurostimulation for SUI in patients, Blowman, Pickles. Emergy, et al. (1991) reported a "cure" or improvement rate of 86 percent in the active group (N=7) and 33 percent in the placebo group (N=6). Electrical stimulation was not used as a single therapy. however; both groups also received instruction in PME.
So -- to which do we attribute the improvement -- the Estim or the PME? At first glance, we might be tempted to say that Estim got 6 out of 7 subjects "improved", whereas PME alone only helped 2 out of 6. But based on other studies of PME alone, we would have expected 4 or 5 of the 6 (66-83%) in the placebo group to have improved with PME alone. So the question becomes "Why did this placebo group do so much WORSE than other PME alone groups?" A likely answer, of course, is that the "blind" didn't work; the patients who got "nothing" from their electrodes became apathetic and didn't work as hard as those who felt the tingle of the stimulator.
Using active and inactive vaginal plug devices in 52 women with SUI, Sand, Richardson, Staskin. et al. (1995) reported objective "cure" or improvement in 48 percent of the active device group and in 13 percent of the placebo group. Active device patients had significant improvements in UI episodes. leakage volume, and vaginal muscle strength and in subjective improvement measures when compared with the placebo group.
Just as there were statistical errors in the biofeedback section, so also we have some sloppy research on this page. In the cited paper, Sand et al actually gave those (48-13) percents for the (subjective data from the) voiding diaries patients were supposed to keep. Their "objective 'cure' or improvement rate" was listed as 62% of the patients and 19% of the control group. (Abstract, p. 72.) The Guideline is off by 14 percentage points!
There are other difficulties in the highly touted Sand study that deserve closer attention. For example, the experimental and control groups were NOT well matched. The "active device" group reported 15 "leaks" per week before therapy, while the "sham device" group reported 19.9 (25% few leaks). And the "active" group was, on average, seven years younger (51 vs. 58).
Seven of the 35 patients (20%) in the "active device" group dropped out, and their data was (properly) excluded from the final analysis. The "active device" group only improved from 14 leaks per week before therapy to 10 leaks per week after 12 weeks of 15-30 minutes of twice daily therapy. Using Burgio's formula for "symptom reduction", that's a whopping 29% improvement after 168 Estim sessions (compared to Burgio's average 85% improvement after 4 biofeedback sessions.) As the lady said, "Where's the Beef?"
On another objective measure, the weekly number of pads used by the active group dropped from 6.2 before to 4.1 after. That's a "Burgio type" improvement of 34%.
Finally, vaginal muscle strength increased from 10.6 mm Hg before to 15.2 mm Hg after, a 43% improvement. (But recall that Susset's patients showed a 300% improvement in only half as many weeks using biofeedback.)
If the data for the "active device" group was rather unremarkable, the same cannot be said for the unfortunate control group. While the Guideline only mentions their overall negligible improvement, it neglects to mention that, by and large, the control group actually got much worse -- which is virtually unheard of in incontinence research. Consider these facts, from Sand's Table III (p. 76):
- The control group went from 20.1 leaks per week before to 27.0 leaks after using a "sham" Estim device. That's 34% WORSE as a result of the "placebo" treatment.
- The control group went from 9.7 pads per week to 11.2 pads per week. That's 15% WORSE.
- The control group went from 30.0 grams pad weight before to 32.3 grams after. That's 8% WORSE.
- Finally, the vaginal muscle strength of the control group dropped from 10.0 before to 8.9 after. That's 11% WORSE.
It is difficult to comprehend how the "sham device" could actually have harmed the control group as much as it did, but the data is presented by the authors without apology. This is the first study in incontinence history in which the control group has regressed on major objective measures.
In any case, one thing is clear. While the authors boast that the "active device" lead to statistically significant differences between the two groups, that difference owes a large part of its "significance" to making the control group worse, instead of making the experimental group better. Compared to other studies, their 29% improvement in symptoms (leaks) makes this one of the least effective therapies ever proposed for treating urinary incontinence.
In other studies with similar settings, anal or vaginal plug devices were used for maximal electrical stimulation for 4 weeks to 3.5 months. 20 minutes to 20 hours/day. "Cure" or improvement rates ranged from 48 to 94 percent in 842 patients with stress, urge, or mixed incontinence. The effects of therapy were sustained 6 weeks to 2 years in 54-77 percent of patients, especially if patients continued to do PME after treatment (Bergman and Eriksen, 1986; Blowman, Pickles, Emery, et al., 1991; Bridges, Denning, Olah, et al., 1988; Caputo, Bensen, McClellan, et al., 1993; Eriksen, Bergrnann, and Eik-Nes, 1989; Eriksen, Bergmann, and Mjolnerod, 1987; Eriksen and Eik-Nes, 1989; Esa, Kiwamoto, Sugiyama, et al., 1991; Fossherg, Sorensen, Ruutu, et al., 1990; Kunkle, Payne, and Whitmore, 1993; Meyer, Dhenin, Sclnrnidt, et al., 1992; Plevnik, Joney, Vrtacnik, et al., 1986; Sand, Richardson, Staskin, et al., 1995; Zoilner-Nielsen and Sarmeisson, 1992).
We note the exceptional variability in outcomes (48 to 94 percent of patients "improved") -- but we have already seen that Sand's 62% "improved" compares with only 29% symptom reduction, so these studies can hardly be called impressive. Incredibly, some researchers used vaginal stimulators as much as 20 hours a day to get results! Unbelievable!
In addition, we note that the persistence of the effect is based largely upon whether or not the patients engage in PME (alone) after the electrical stimulation ended. (Other studies involved the daily use of the stimulator for up to a year, and some even longer.)
One study of cognitively impaired patients in a nursing home showed no significant effect of stimulation, with a trend toward increased wetness (Lamhut, Jackson, and Wall, 1992).
That's an incredible understatement. The Lamhut study is especially important for understanding the role of electrical stimulation because they intentionally used demented nursing home patients for research subjects. In other words, this is the only study whose patients could not do PME in time with the zaps of the stimulator! The clause "with a trend toward increased wetness" is a polite way of saying that, not only did electrical stimulation alone (without PMEs) not do any good, but fully a quarter of the patients actually got WORSE using this very popular and widely advertised Estim product.
Summary of findings. Research indicates that pelvic floor electrical stimulation can significantly reduce UI in women with SUI, and may be effective in men and women with mixed and urge UI. Stimulation may be effective when augmented with other pelvic muscle rehabilitation therapies.
More accurately, "Stimulation may ONLY be effective when augmented with other pelvic muscle rehabilitation therapies."
Minimal adverse side effects occur with this treatment.
This conclusion warrants closer examination. Let's return again to the Sand et al 1995 study, which is the basis for so many Estim sales in the United States, to see how minimal those adverse side effects were.
According to the authors, "there were no severe or irreversible adverse events during the study" (p. 77). That, in itself, does not rule out moderate nor acute adverse effects. What did they actually find?
- Vaginal irritation was noted by 14% of the active group and 12% of the sham group. (The device, not the electrical current, appears to be the culprit.)
- "Occasional episodes of pain" were reported by 11% of the actives and 6% of the sham group. (Maybe the electrical current did cause "pain".)
- Vaginal infections were noted in 11% of the actives and 12% of the controls. (This is difficult to understand since the Estim electrodes are very similar to the EMG biofeedback sensors in mechanical properties, yet no one has reported vaginal infections from EMG sensors.)
- Urinary tract infections were found in 3% of the actives and 12% of the control group.
All things considered, it appears that 1 in 10 patients is likely to suffer an adverse, albeit tempoary, effect from this popular electrical stimulation device. Since less than two out of three patients is going to show even a 50% improvement, it may be too high a risk to take, considering, of course, that all forms of biofeedback show substantially better outcomes.
Treatment using stimulation requires monitoring by a health care provider to determine effectiveness.
The purpose of this caveat is to counter the tendency of some therapists to give the patient an Estim device and send them home for a couple of months to work on their own. The purpose of weekly office visits is not to milk the patient's insurance, but to assure that the patient is doing the exercises correctly. Since one misguided patient can spend a great deal of time and money getting back on track, the net outcome for careful clinical supervision is clearly justified.
Further research is needed to determine the efficacy of pelvic floor stimulation used alone or in combination with other therapies. Standardization of the parameters of the techniques used, such as that proposed by the International Continence Society, is necessary to allow further comparison of study results.
All things considered, it is difficult to comprehend how the AHCPR could give a "B" rating to the evidence in support of Electrical Stimulation. A clue may be found in the sponsorship of organizations like HIP (now the National Association for Continence [NAFC]) and Simon Foundation. The several Estim manufacturers have spent a fortune on promotional activities designed to bring their products up to the level of acceptance of biofeedback devices. And a great many people have been fooled as a result.
InContiNet welcomes opposing points of view. Please publish your comments through the "Pelvic Muscle Dysfunction Discussion Forum", accessible near the middle of our home page.
This is one of a series of "Critical Reviews" of Incontinence-related research. Click on the name to see more reviews.
Copyright 1997 by InContiNet. All Rights Reserved.
Draft of: Wednesday, May 04, 2005
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