Reporting on relative risks and surrogate endpoints, this story framed the benefits a bit too optimistically.
The story uses phrases like “significantly lower risk” and “substantially higher” scores to describe the benefits conferred by an experimental drug for knee osteoarthritis. However, it doesn’t back up these descriptions with numbers. We think that’s a problem, because we don’t always see eye to eye with researchers as to what these terms actually mean. To avoid any confusion, we insist that health journalists make some attempt to quantify benefits in absolute terms. That way, readers can decide for themselves whether the benefits are “significant” or “substantial.”
Osteoarthritis or arthritis of aging increases we age. X-rays show that findings of arthritis become more common as we grow older and that by the time we’re senior citizens, almost all of us have x-ray findings of arthritis. Treatments generally focus on treating the symptoms of arthritis when they occur. It is important to realize that just because an x-rays shows arthritis doesn’t mean the person is bothered by it. Many studies have shown that there is a disconnect between the picture and the person’s symptoms of pain or functional impairment. Currently prevention of osteoarthritis focuses on physical activity to minimize the symptoms of osteoarthritis but not actually in keeping it from occurring in the first place. That is where a new treatment, such as strontium, would be a welcome addition, if it actually was shown to decrease cartilage damage that often is part of the development and progression of osteoarthritis. However, this study that reports those treated with strontium had less x-ray progression over time than those who did not, will require further details of the study when they are published as well as confirming these results in other patients. Moreover, whether these x-ray findings translate into less pain, better function, fewer medications, injections and surgery – what matters to patients remains to be proven.
The story did not discuss costs. Presumably, since this drug is already sold outside of the U.S., the story could have provided at least a ballpark estimate.
The story wasn’t precise enough here. It discusses a cartilage loss threshold that is associated with “significantly lower risk” for knee replacement surgery, but doesn’t quantify the difference. It goes on to say that “30% to 40% fewer patients taking strontium reached this [surgery] threshold compared with placebo” — a relative comparison that probably provides an inflated sense of the benefits. A comparison of the absolute numbers of patients in each group who reached this threshold would have sounded less impressive, but would have been more useful for decision making.
The story also says that patients taking the 2-gram dose of strontium scored “substantially” better than the other groups on certain pain scores. But what seems “substantial” to researchers and reporters may look less solid to patients. That’s why we always ask journalists to back up claims of benefit with actual numbers.
The story notes that strontium can increase the risk for deep vein thrombosis, but doesn’t indicate whether the drug was associated with any adverse effects in the study.
We liked that this story had a caveat about limited peer review that conference presentations receive and that it is too soon to draw firm conclusions. That is now boilerplate language on such stories by WebMD. However, the story didn’t clearly explain that cartilage loss, and the surgery threshold that are the main focus of the article, are surrogates, or proxies, for the real outcomes that matter to patients. While it is expected that a slower rate of cartilage loss would translate to better outcomes for patients, particularly fewer knee replacement surgeries, we won’t know for certain until a study follows patients for a longer time period and finds out what happens to them.
Descriptions of the prevalence and burden of knee osteoarthritis seemed reasonable.
The story provides comments from a spokesman for the American College of Rheumatology. It also notes that several researchers reported financial ties to drug companies, including Servier Laboratories, which makes strontium ranelate.
The story notes that there are no drugs currently available that can delay the progression of knee osteoarthritis, and that current osteoarthritis treatments, such as medication and physical therapy, are aimed at improving symptoms.
The story notes that strontium ranelate is available as a prescription drug for osteoporosis in some other countries, but is not approved in the U.S. It explains that other strontium formulations are available as nutritional supplements in the U.S., but that these might not work the same way that the strontium drug tested in the study works.
Because the story explained that a form of strontium is available as a prescription drug for osteoporosis in several countries and because it is clear that the study in question is about a new use for this medication, we’ll give the story the benefit of the doubt – even though it could have explained better that the idea that strontium ranelate can be effective for osteoarthritis is not entirely new. In studies of women taking the drug for osteoporosis, the drug seemed to have a beneficial effect on markers of cartilage degradation and symptoms of spinal osteoarthritis. Those studies paved the way for the trial being reported on here, but there was no mention of that previous research.
It doesn’t look like the story relied inappropriately on this press release.