When it comes to providing clear explanations of complex medical and health-related issues, there is no one better than Aaron Carroll. As a person who is regularly looking for answers in these areas, I am a huge fan. I watch his videos on Healthcare Triage, read his articles in the New York Times, and follow him on Twitter. His excitement about food, ideas, travel, and the latest exploits of his kids are fun to read about. You probably sense that there is a “but” coming – and here it is: Aaron’s enthusiasm about large studies makes me uneasy.
Large studies inform us about what happened to a particular group of individuals under a specific set of circumstances. They can provide guidance for medical practitioners when they deal with individuals who appear to be similar to that group; they can give doctors an idea of what to look for. What can large studies tell doctors for certain about any given individual? Absolutely nothing.
Problems arise when the guidance provided by studies morphs into a hard-and-fast rule about what must always or never be done. In some cases conclusions from studies are over-generalized and made to apply to situations which are beyond the scope of the studies.
“Arthroscopic Surgery Isn’t Going to Fix Your Knee,” a recent HCT video, talks about a recent review and meta-analysis of studies on arthroscopic surgery for degenerative knee. Both the title and the video itself make it sound as though arthroscopic surgery is always a waste of time and money. Yet the studies were really about attempts to repair degenerative knees. They weren’t intended to address the issue of repairing knee injuries.
When patients fail to conform the rules derived from large studies, they may have great difficulty securing proper medical treatment. Here is what happened to a friend of mine, a man in his mid-seventies, a natural athlete who was then playing racquetball a couple of times a week. One afternoon he tripped as he was going up some stairs. In instant he went from normal to hardly being able to walk.
After an x-ray at the hospital, he went to a local orthopedics practice where the first doctor said, “You have a torn meniscus. It can be repaired with arthroscopic surgery – we do them all the time.” That sounded fine to my friend but when he was passed along to a surgeon in the same office he got a different pitch. The surgeon said, “You have advanced arthritis and surgery would not do any good.” He then gave my friend a cortisone shot, which had no effect on his pain or disability and told him that he would probably require a knee replacement in the foreseeable future.
The story about advanced arthritis didn’t sound quite right to my friend. Before the injury, he had been able to squat down and remain there for minutes at a time (the pose of cowboys in front of a campfire). He sought out a second orthopedist. This doctor, a woman, said, “We don’t normally do knee surgeries on people in their seventies but I think you are the exception.” Several weeks later, after performing the surgery, she said, “This knee was like a Ping-Pong ball. I’ve seen people in their forties who didn’t have knees as good as this.” This was an injury, not advanced arthritis. The first surgeon had lied because he didn’t want to operate on a man in his seventies. My friend went back to playing racquetball.
Doctors today have impossible schedules. They see each patient for fifteen minutes, if that. Under these circumstances, over-generalizations and rules based on large studies can become a tempting substitute for close observation and careful analysis of an individual situation. The likely consequences are improper care for the patient and unnecessary expense for the health care system. In thinking about my friend’s experience I have sometimes wondered how many older people with injured, but otherwise healthy, knees have been steered into having knee replacements when all they needed was a simple arthroscopic surgery.