This story parrots a news release sent out by Oxford University about a study published in the journal BMJ Open. The study concludes that partial knee replacements would — in many cases — leave patients “better off” than total knee replacements.
With no independent reporting, the story glosses over how the study was conducted, what was measured, and what the limitations were. It also didn’t discuss harms of surgery, among other problems. An over-reliance on publicity materials appears to be a pattern — last week the Guardian received a 1-star score from us for a different story that also simply restated what the news release said.
Knee replacement surgeries are not uncommon. A 2015 study reported that, as of 2010, there were 4.7 million people in the U.S. who had received a total knee replacement. If partial knee replacement (also called a unicompartmental knee replacement, or UKR) is an option for many patients, and the partial version could improve outcomes and reduce medical costs, then this is a finding with the potential to significantly improve life for patients (and make U.S. insurers happier in the process).
However, it’s important to highlight the risks associated with such a decision — even if those risks could potentially be reduced by seeing an increase in partial replacement surgeries over time.
The importance of this research is that for some people a less-invasive surgical procedure may be an option, but the choice isn’t quite so clearcut as the researchers imply.
This story ran in the U.S. edition of the Guardian. Generally, we expect those stories to acknowledge that the U.S. patients have to pay for their healthcare, and what those costs might be. However, in this case, because the research is looking at some benefits specific to the UK’s National Health Service, we’ll rate this N/A. It does include a small mention on this topic: “Partial replacements are also cheaper, say researchers from Oxford University.”
The story tells readers that “Many more people facing surgery for knee problems would be better off with a partial rather than total knee replacement, which should allow them to recover faster.” But it doesn’t tell readers how much faster. It also doesn’t make clear what the benefits of the surgery are compared to, well, not having any surgery at all.
In addition to not quantifying the benefits, the story also doesn’t tell readers exactly what the researchers were measuring, which were “quality adjusted life years” (QALYs). QALYs are a way of accounting for both the quantity and quality of a patient’s life, and are used primarily in an economic context. i.e., QALYs are used to assess the cost-effectiveness, or value, of a medical procedure.
In this case, the study found that patients had QALY gains for partial replacements, compared to total knee replacements, and that the gains varied depending on both the patient’s sex and age. The QALY outcomes were also influenced by whether the person conducting the partial surgery did such operations frequently.
What risks are associated with getting either surgery? The story simply doesn’t tell us.
When considering harms, one needs to keep in mind the side effects of surgery, the recovery from surgery, how they function after recovery and then whether there are differences in the need for subsequent procedures.
It’s not clear from the story how the study was conducted. In one place it refers to “an analysis of the data routinely collected by the National Joint Registry.” Elsewhere the story cites a researcher as saying that the study was “able to use real data, from very large numbers of people, about their actual operations, their [general practitioner] visit, and their own reported quality of life outcomes in a way that is not always possible.” But, put simply, that’s rather vague. What sort of data were they looking at? How were they using the data? Were there limitations in the data that required researchers to make any assumptions? The story doesn’t tell us.
Ideally, such analyses would use experimental data. However, this study uses observational data. Little is provided about where this data came from and how patients who had one procedure or the other differed. The lack of details makes it harder for the reader to understand what was done in this study.
One possible concern here would be that there is an assumption that surgery — either partial or total replacement — is a foregone conclusion for patients who have osteoarthritis of the knee. That’s not true — there are other treatment options available. However, the story doesn’t quite say that. It instead says that osteoarthritis is “the main reason for [knee replacement] surgery.” Because there are certainly cases of osteoarthritis where replacement, or partial replacement, are indicated — and it can be inferred that the story is referring only to those cases — this gets a satisfactory rating.
The story does not appear to incorporate input from any independent sources. All the quotes were taken from the news release, without attribution.
If, as we noted under “Disease Mongering,” the story is focused only on patients that require either partial or total knee replacement, then the only alternatives are, well, partial or total knee replacement. And the story refers explicitly to both.
But there are nuances missing. The partial procedure is thought to be a simpler one. As such, it may lead patients to undergo surgery at an earlier stage than they may otherwise have if they had the full replacement. As such, an alternative of waiting would be reasonable. This really is the challenge. There are few things between conservative measures and surgery for patients with knee arthritis.
The story makes clear that partial knee replacement surgery is available.
This is not the first study to evaluate the outcomes of partial knee procedures (see this 2011 paper, for example). It is not even the first study to compare the outcomes from partial surgery to the outcomes from total knee replacements (see these two studies on the same cohort of patients from 1998 and 2009). So what sets this new study apart? The story does cite a researcher as saying “The main strength of this study is that we were able to use real data, from very large numbers of people, about their actual operations, their GP visit, and their own reported quality of life outcomes in a way that is not always possible.” However, without at least some discussion of the previous work, any comparison is impossible.
It appears that all of the information in the story, including the quotes from the study authors, comes from a news release issued by the study authors’ research institution. The story does not credit the news release.
For example, this quote appears in both the news story and the news release:
“The main strength of this study is that we were able to use real data, from very large numbers of people, about their actual operations, their GP visit, and their own reported quality of life outcomes in a way that is not always possible.”