Comparative predictive performance of the CORN and culturally adapted Munro scales for intraoperatively acquired pressure injury: a retrospective cohort study
In a retrospective cohort study of 296 surgical patients in Shenzhen, the Chinese-developed CORN scale demonstrated superior predictive performance for intraoperatively acquired pressure injuries compared to the culturally adapted Munro scale; however, this advantage was largely driven by operative duration items and diminished in sensitivity analyses, indicating a need for prospective multicentre validation before either scale can be recommended.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Every year, millions of people undergo surgery, a process that requires them to lie perfectly still for hours while under the influence of anesthesia. Because they cannot shift their weight or adjust their position, the constant pressure of their own body against the operating table can damage the skin and underlying tissue. This specific type of wound, known as an intraoperatively acquired pressure injury, is a painful complication that can lead to longer hospital stays and higher medical costs. To prevent these injuries, nurses rely on risk-assessment tools: checklists that look at factors like a patient's age, body weight, how long the surgery might last, and their overall health to predict who is most likely to develop a wound. The goal is to identify high-risk patients early so that extra protective measures can be taken before the surgery begins. However, there is no single, universally agreed-upon checklist for surgical patients, and different hospitals use different tools, making it difficult to know which one works best.
In a recent study conducted at a large hospital in Shenzhen, China, researchers set out to compare two specific tools designed for this purpose. One is the CORN scale, a newer tool developed specifically for Chinese patients by a national nursing committee. The other is a culturally adapted version of the Munro scale, a tool originally designed for surgical patients in the West. The researchers wanted to see which of these two checklists was better at predicting which patients would actually develop a pressure injury during their operation. They looked back at the medical records of nearly 300 adult patients who had undergone various types of surgery, ranging from orthopedics to neurosurgery. For each patient, two trained nurses independently calculated the scores on both scales using the information available in the records, without knowing whether the patient had developed an injury. They then compared these scores against the actual outcome: whether or not the patient developed a pressure injury, which was confirmed by a hospital team using standard medical guidelines.
The study found that the CORN scale was generally better at distinguishing between patients who would develop an injury and those who would not. When the researchers looked at the scores calculated before surgery, the CORN tool was significantly more accurate than the Munro scale. The same was true for the scores calculated during the surgery. In simple terms, the CORN scale was more successful at identifying the patients who were truly at risk while correctly ruling out those who were not. The Munro scale, by contrast, tended to flag far more people as being at risk, even when they were not, which could lead to unnecessary use of resources.
However, the researchers discovered that the advantage of the CORN scale was not as broad as it first appeared. When they broke down the checklists to see which specific questions were driving the results, they found that the CORN scale's superior performance relied heavily on a single item: the expected length of the surgery. The CORN tool asks for the anticipated duration of the operation before the surgery starts, and this single piece of information was a very strong predictor of injury on its own. The Munro scale, in its current adapted form, does not include the expected duration in its preoperative section; it only records the actual time after the surgery is over. When the researchers removed the "expected duration" question from the CORN scale and compared the remaining parts of both tools, the difference in their performance disappeared. This suggests that the main reason the CORN scale worked so well in this study was simply that it asked about how long the surgery would take, a factor that the other tool did not weigh as heavily at the preoperative stage.
The study also highlighted that while the CORN scale performed better in this specific group of patients, the results were not a final verdict. The researchers noted that the study was conducted at a single hospital over a short period, and the patient mix included many people with lower risks of injury, such as younger patients and those having shorter operations. Because the study was retrospective, meaning the scores were calculated after the fact from existing records, the accuracy of the results depends on how well the original medical records were filled out. The authors concluded that while the CORN scale showed promise, particularly because it is shorter and includes the crucial factor of anticipated surgery time, more research is needed. They emphasized that before one scale can be recommended over the other for routine use across different hospitals and patient populations, the tools must be tested in larger, multi-center studies to ensure the findings hold true in different settings. Until then, the choice of tool remains a matter of local practice and ongoing evaluation.
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