SCI Forum Reports
Prevention and Primary Care in SCI
October 12 , 2004
- Colon Cancer Screening
- Cardiovascular Screening
- Prostate Cancer Screening
- Breast Cancer Screening
- Osteoporosis Screening
- Urologic Screening (Abdominal Ultrasound)
- Do I need a primary care doctor, a physiatrist, or both?
- How often should I see a doctor?
- Follow-up questions on skin cancer screening, foot care, and urodynamic studies
People with SCI quickly learn that prevention is a key factor in staying healthy and avoiding complications. But do they know how often to get a medical checkup? Or whether they need a regular primary care doctor, or a rehab doctor (physiatrist), or both? Or what routine screening tests they should have for cancer and other diseases?
Chris Knight, MD , assistant professor in General Medicine at the UW, probed these questions in his talk "Prevention: Is an ounce worth a ton of tests?"
"You've all heard the saying that an ounce of prevention is worth a pound of cure, and we do believe that and work in that model," Knight said. "But how do you know if you need that test you just read about in the paper?"
Knight began with a review of general screening principles that can be used to guide decisions about screening. For any test, the advantages (problems detected, lives saved) must be weighed against the possible disadvantages (cost, discomfort, risks).
Knight's first principle: If it ain't fixable, don't break it . "If you're testing for something, it should be something you can fix," he said. "It doesn't help a lot to find diagnoses that you can't do anything about. If someone thinks they're healthy and you tell them, 'oh no, you've got something wrong with you,' it better be something you can treat."
Second: What you know can hurt you. Knight believes that the false positive result (shows you have a problem when you really don't) is often a far bigger problem than a false negative (shows you don't have a problem when you really do). "People worry that a test might miss something," he said. "Well, if they miss something, you're no worse off than if you didn't have the test at all. Whereas if they find something, usually you have to undergo more expensive and invasive tests after that."
And third: Don't burn the haystack to find the needle. "The rarer the disease, the safer the test needs to be," Knight said. "Even if you take a very safe test, say only 1 in 10,000 people who have the test get a complication from it. Apply it to one million people, and that's 100 complications. If we're proposing doing this test on huge numbers of people, there have to be enough people out there with the disease" to balance out the number of problems likely to be caused by the tests themselves.
Knight assigned an effectiveness rating to each test:
"Definitely helps" means there's good scientific evidence the test is beneficial, "by which I mean it usually saves lives," he said.
"Probably helps" means that while evidence may be weak, there's at least a general consensus among practitioners that this probably does more good than harm.
"Might help" means it seems like a good idea, but there's only slight evidence that it works and little consensus that it's really going to benefit people in the long run.
- Fecal Blood Testing
This is a simple process in which the patient obtains a stool sample at home and mails it to a lab. It's non-invasive, very inexpensive, "and it actually works," Knight said. "A large trial in the mid-1980s found a 30% reduction in colon cancer deaths (among those tested)." Those with a positive fecal blood test went on to have a colonoscopy looking for polyps and cancer, and were treated for whatever was there.
The downside of this test is frequency (it must be done every year) and inaccuracy. "There's a fairly high rate of false positives, which means a lot of people with normal colons will get colonoscopies, Knight said. "And it also misses some cancers. But it's the one test in colon cancer screening that's been proven to be of benefit."
- Flexible sigmoidoscopy
The lower third of the colon (sigmoid) is inspected with a thin flexible tube inserted into the rectum. Compared to colonoscopy (below), flexible sigmoidoscopy is less invasive, safer, cheaper and doesn't require flushing of the whole colon. It can't detect abnormalities in the upper two-thirds of the colon, but most polyps and cancers occur in that last third of the colon, anyway. Many people with cancers in the upper two-thirds also have polyps in the lower third, and a finding of polyps always prompts a colonoscopy.
This is the most accurate test for colon cancer and examines the entire colon. "It is actually more comfortable than flexible sigmoidoscopy because the patient is sedated and doesn't remember it," Knight said. The bowel preparation is memorable, however, because it requires cleaning out the bowel by drinking clear liquids for two days, followed by four-to-eight liters of a purgative that causes diarrhea and "just shoots through you like rockets," he added. This bowel preparation could be especially challenging for persons with neurogenic bowel due to SCI. "The big disadvantage is a complication rate of 1 per 1,000 procedures-such as infection, perforation, bleeding-that might require hospitalization. And it's very expensive- between $500 and $2500, depending on how much you pay out of pocket."
- Virtual (CT) colonoscopy
"This is the newest kid on the block," Knight reported, and still controversial. The bowel is inflated with air (similar to colonoscopy), and a CT scanner is used to look inside the bowel. "Compared to having a scope put up there, this is much faster and less invasive," Knight said. "But you still have to go through the complete bowel prep. And if it shows anything abnormal, you'll need to have a colonoscopy anyway." He rated it "might help" because, although one study last year showed it to be as effective as colonoscopy, subsequent studies found this not to be true.
- Cholesterol testing
"This (blood test) is a good predictor of risk and in some ways a perfect screening test," Knight said, because people with higher cholesterol have greater risk of heart disease, and lowering cholesterol reduces risk. While the required 12-hour fast can be uncomfortable and inconvenient, it allows the practitioner to screen for diabetes at the same time. The treatment guidelines are changing constantly, however, and this can be confusing for those who follow the subject in the popular press rather than the medical literature. And treatment is expensive. "Most medications cost between $50-$150 a month." Knight continued. "And that's for the rest of your life."
- C-reactive protein
C-reactive protein is a substance that indicates the presence of inflammation in the body. If there is no other infection or inflammation (such as arthritis) going on, an elevated C-reactive protein is a predictor of heart disease "to some degree," Knight said. "The problem is, you can't really do anything to lower it" or reduce the risk, and as such, it fails Knight's first principle: If it ain't fixable, don't break it. This test may be helpful in individual cases, such as a patient with borderline cholesterol. "It's one piece of information I could use in deciding whether to treat him or not," Knight explained. "But I don't advocate doing it on everybody."
- Electron-beam CT
This fast, non-invasive scanning technique is a good predictor of atherosclerosis and detects blockages in the coronary arteries or elsewhere in the body. Like C-reactive protein (above), however, "you can't change what it finds," Knight said. "So it's hard to know how to interpret the results. In addition, it's often an out-of-pocket expense for the patient. I don't usually encourage people to get this."
Cardiovascular testing in SCI: A Unique Dilemma
People with severely diminished aerobic exercise capacity due to SCI have a higher risk for heart disease, and unfortunately, the number one marker we have for heart disease-poor tolerance for exercise-is difficult to measure in SCI. "If you have functional upper extremities, we can do a stress test with arm treadmills," Knight said. If not, clinicians can induce "pharmacologic stress" with an injection of adenosine, dipyridamole, or dobutamine. However, "we don't like to give the shots because they're slightly higher risk than exercise, and the information is not quite as good," Knight added.
There are two ways to screen for prostate cancer: a blood test called PSA (prostate-specific antigen), and physical examination of the rectum.
PSA is a simple test, but not a very accurate one. "Many people with a positive PSA do not have prostate cancer, and many with a negative PSA do have prostate cancer," Knight said. "If you have a positive PSA, you're going to have to go to the urologist and have a prostate biopsy," which is invasive, and usually nothing is found. "That happens often enough that it's a significant problem."
The rectal exam is cheaper and easier, but even less accurate. If you can feel something, (the cancer) is already pretty big, and you may not be able to remove it surgically, Knight explained. As yet there have been no large studies showing which screening method saves more lives. Results from a large PSA trial should be available by the end of the decade.
To further complicate matters, not everyone with prostate cancer needs surgery. "As people get older, we find from autopsies that nearly half of men in their 80s have undiagnosed prostate cancer," Knight said. While the likelihood of having prostate cancer increases with age, "the likelihood of dying from it is not as high as if you were younger. So it might make sense to have the test when you're younger rather than older." Until more studies are done, Knight remains cautious about recommending the PSA test.
Despite ongoing debate about this test, clinicians generally agree that mammography is beneficial in women age 50 and over, and possibly in women ages 40-50. Mammography can be uncomfortable, and a false positive can lead to unnecessary biopsy, which happens fairly frequently. "That said, it is good at finding breast cancers early, and breast cancer can be a bad disease when you find it late," Knight concluded. "I encourage mammography."
So many people with SCI have osteoporosis (low bone density), particularly in the femur and hip, that it might seem reasonable to skip the screening step and just treat everyone for it, Knight said.
"But the problem is that nobody knows what to do for osteoporosis in SCI," he continued. "We know that with treatment you can increase bone mineral density, which is the amount of calcium in your bones, and that there is some correlation between the amount of calcium in your bones and the risk for fracture." While treatments for post-menopausal women have been studied in large trials, that's not the case in the SCI population. And since there are differences in the way these two populations use their bones, clinicians don't know if osteoporosis puts them at the same risk for fracture.
"It's a very complicated question, and I can't make a firm recommendation one way or another," Knight said. "It's worth talking with your doctor, first about screening, and then about treatment if osteoporosis is found, which is very likely."
"Bone is dependent on weight to survive," he went on. "It's constantly remodeling and compensates for the amount of load it has to bear. This is why your bones are much thinner in your legs. We can give you medications that will cause all of the bones in your body to retain more minerals. But it's expensive, it's a pill you need the rest of your life, and we don't know if it will lower your risk of breaking something. One reason we don't know is that the amount of osteoporosis in your bones is substantially worse than the average post-menopausal woman. The amount of difference medications make might not be enough."
Knight expressed doubt that using a standing frame would have a significant effect on bone density because "it takes quite a bit of weight-bearing exercise to increase bone density among people who are normally on their feet," and a person with SCI probably couldn't spend enough time on it to get improvement. Using both medications and a standing frame or other weigh-bearing equipment might improve bone density measurably, but whether it would be enough to reduce fractures in SCI is still unknown.
A common screening tool for urologic problems, abdominal ultrasound is non-invasive and may also detect aortic aneurysm early. According to Knight, most primary care physicians are not aware that people with SCI have a greater risk for urological problems and are not familiar with the screening protocols for this. "The rate of complications like renal obstruction and kidney stones is not only higher in SCI, but you don't usually have the symptoms to tell us they're there," he said. While unexpected findings or small aneurysms sometimes can be controversial, this test is worth doing in at-risk populations such as SCI.
In addition to their expertise in general medical problems such as high blood pressure and diabetes, primary care physicians are knowledgeable about all the risks and benefits of an ever-expanding assortment of screening tests. "And the literature changes frequently," Knight said. "So this is something that I have to spend a lot of time trying to stay on top of. Most primary care docs don't have particular expertise in SCI, however." Physiatrists are specialists with experience and skill in the management of SCI-specific issues and maximizing function.
"Patients younger than 50 who don't have many medical problems may do well without a primary care doc because most of their care is going to focus on SCI-related problems that are chronic to their injury, and on maximizing function," Knight pointed out. As you get over 50, things change. "Fifty is sort of a cut-off for a lot of these screening tests. And as age-related problems come up, you probably will benefit most from a collaboration between doctors. We are never going to replace a physiatrist because we just don't have that expertise, nor are we trained in it either during medical school or residency. I think we have a role, but I would still want to work with a physiatrist."
Physicians in the UW Department of Rehabilitation Medicine recommend that persons with SCI see a physiatrist at least yearly, even if there are no problems, because there are many preventable health problems and medical complications that are common in SCI.
Is skin cancer screening necessary?
"It's an excellent idea" to get regular skin checks as part of the general physical exam, Knight said. "It can be done by any doc who's comfortable looking at skin lesions, and makes a lot of sense."
What about foot care?
"People without sensation in their feet need meticulous foot care, done either by themselves or by a podiatrist, or physiatrist if they're comfortable with it," Knight said.
Do urodynamic studies measure kidney function?
The purpose of urodynamics is to make sure the bladder is draining effectively and to guide the bladder management plan. These studies are important in diagnosing problems that involve loss of urinary control, urinary retention (inability to pass urine), chronic urinary tract infections, and frequent urination. A creatinine blood test measures kidney function.