What is a myth? A myth can be defined as a widely held belief or idea that must be considered untrue based on the available evidence. In many cases myths are stories that allow a culture to continue to hold on to a particular belief, even if this belief is contradicted by evidence.
Myths influence us in subtle ways. If a myth is strong enough, it can even influence how personal experiences are interpreted. In a way, myths can change the way reality is perceived, in what is known as “confirmation bias”.
If, for instance, a certain treatment is believed to be the most effective, any supporting experience is likely to be considered as definite proof, ‘confirming´ the belief as true – even if the experience was really just an exception.
On the other hand, if an experience contradicts popular belief, it will often simply be dismissed as being “the exception that proves the rule”.
Of course, this doesn’t mean that nurses should not trust their experiences – quite the contrary. But the experience-based knowledge should be considered together with all the evidence-based knowledge, where such scientific evidence exists.
Why is this important for nurses? Because even with a high level of personal experience it will still be a subset of the total evidence for or against a given treatment or practice.
Together with the experts of the Coloplast Global COF board, some common questions about convexity were discussed. Is there enough scientific clinical evidence to determine what beliefs are facts and which are myths? Where is there a need for more research?
Question #1 How much do we really know about convexity?
Despite the many convexity products, leakage is still a critical issue and research on convexity is in its infancy. With the variety of convexity solutions available, the knowledge base on how and when to use convex solutions should be convincing. But reality shows that there is very little solid research and evidence-based findings8 available, stressing that it is important to be observant and aware of the few scientific articles that are available. It is clear that there is a need to learn a lot more about convexity to make the best possible decisions.
Question #2 Does convex cause more pressure complications?
This seems to make intuitive sense, and traditional convex solutions are often associated with risk of pressure ulcers when discussed in the circles of ostomy care experts. But the reality is that evidence is insufficient to document if and how convexity and pressure complications are related. 9More than three out of four of the COF experts agreed that in their professional experience, they had no proof of a direct relation. At least, it is an area where more evidence is needed.
Question #3 Is convex a poor choice for newly performed ostomies because of the risk of mucocutaneous separation?
As discussed on page 6 there is data to suggest that convex solutions are perhaps underrepresented among new ostomy patients. Perhaps some nurses are cautious in recommending a convex solution right after surgery even though their professional judgment tells them that it would be the optimal solution? Could the perception of increased risk of mucocutaneous separation be one of the reasons? Again, there is not a lot of evidence, but the available evidence does not confirm this concern nor has it been proven through research10.This is supported by the COF experts, where 11 of 12 consider this a myth based on their practical experience.
Question #4 Can convex in combination with a ring cause pressure complications?
While there is no evidence that convex solutions are problematic as such, there is indeed some scientific literature suggesting that the addition of a ring to a traditional convex solution could cause ‘intense pressure’8. Is this a fact, then? The quoted study stresses that this effect is observed for ‘some’ patients, but not all. This matches with the feedback from the Global COF experts, where about half of the group had observed this phenomenon.
Question#5 Does deep convex cause more pressure complications than light convex?
When looking at the traditional deep convex appliances, it does feel like the hard shells could cause more pressure. Yet, the evidence shows that a light convexity solution can actually place the same or more pressure on the skin11, perhaps suggesting that it’s more about finding a good fit for the individual patient, rather than about the depth of convexity. Three out of four of the COF experts agreed that deep convex doesn’t necessarily cause more pressure complications than light convex.