CreamScan Research Evaluation Standards
Intro
Fundamental conflict of interest – does cosmetic science explore or sell?
There is a discussion even among cosmetic chemists on a matter of how scientific a cosmetic science is today and should be.Here are a few quotes from one of the leaders of cosmetic chemistry industry, Dr. Johann W. Wiechers from his book “Memories of a Cosmetically Disturbed Mind” (22)."… Especially because cosmetic science is a commercial science. Why? Academic science is done for finding out how 'things' work, and to test or deny a hypothesis, whereas commercial science is science done for finding reasons for selling your product."
"A large proportion of us are doing science to sell products and not to explain things. Cosmetic science is therefore very often comparative science (how good is my product or my ingredient doing relative towards my competitor’s product or ingredient) instead of explanatory science (how does my product work).”So we conclude here that, cosmetic science, being an integral part of cosmetic industry, focused to sell new molecules to manufacturers or products to the end consumers, by default, has a built-in bias to demonstrate their efficacy.
Objectives
Does a particular research paper prove that an active ingredient reduced wrinkles?
If yes, by how many percent?
1. Study should confirm efficacy on humans, not animals
2. Topical application of emulsion, no injections, microneedles, no oral intake or combined
2. In-vivo, not ex vivo or in vitro
“The problem is that usually these lab studies do not translate to positive effects when used in real-life products. Just because an ingredient shows a benefit when applied directly to human skin cells in a petri dish does not mean it will have any effect when delivered directly to the skin from a lotion or other personal care product.”
3. At least 20 people
4. Vehicle (placebo) or positive controlled
Looking study by study we confirm, that out of 12 studies, in 11 studies (90%+) vehicle only had a positive effect on wrinkles (3-11).
In 6 studies out of 12, vehicle had a stronger effect on wrinkles, than active only, calculated as the result of "vehicle + active formulation minus result of vehicle only formulation (3-8).
On average, vehicle only (=moisturizer) could improve wrinkles by 12%. Vehicle + active could improve wrinkles by 19%. That means that on average, the effect of the vehicle itself (12% improvement) was 1.5 times stronger than an average effect of actives isolated from vehicle (7% improvement).
How the basic moisturizer can works against wrinkles?
We will discuss it in more details elsewhere to elaborate the fact that a basic moisturizer is the most efficient part of the anti-wrinkle strategy.The key hypothesis is that “use of skin moisturizers should delay or slow down the rate of persistent wrinkling, perhaps by plasticizing the stratum corneum (upper skin layer), thereby diminishing the formation of temporary wrinkles during facial expression and thus the potential for persistent wrinkles” – that was a one of the conclusions in a 8 year (!) study to find out how expression lines transform into persistent wrinkles (18) also confirmed by other studies.Now let's go back now to the anti-wrinkle efficacy. How can we isolate the effect of the active from the effect of the vehicle-placebo-moisturizer? There is only one way to do it. Compare the results of vehicle + active vs. vehicle alone.So studies claiming that a cream with a magic ingredient improved wrinkles by x% vs baseline, are inconclusive, if they don't compare a treatment formulation to the same formulation, but without an active: vehicle (placebo). Because the wrinkle reduction effect can be caused not by a reviewed active ingredient, but by other moisturizing ingredients present in the formula.Positive control
A few words about positive control. We see it as a possible, although less reliable alternative to a vehicle control. It is less reliable because in a double-blind study, in case with placebo/vehicle control, a researcher doesn't know what result he looks at, a vehicle or an active, so he has no room for potential bias.In case with positive control, however, a researcher, even if blinded, has room for bias. Because to prove that the reviewed ingredient has the same efficacy as positive control, both formulas can be given the same efficacy evaluation, in case the subjective evaluation method is used (like expert grading of wrinkle severity). For that a researcher doesn't need to know what result he is looking at, he just may give the same evaluation to all the results and at the end we can claim that ingredient X has the same efficacy as tretinoin, for example.Therefore we only take into consideration positive control, if there is no subjective method used to evaluate the results of the participants, but only an objective and quantitative method like computer grading or profilometry.Comparability
The last part is about comparability of a vehicle or positive control. As we said above, the whole point of a vehicle control is to exclude the anti-wrinkle effect of other ingredients in a formula. The only way to achieve that is to compare the same formulations, one with active and another one without it, or, in case with a positive control, with another active.We assume that such an approach is always the case, even if exact active and vehicle formulations are not reported. But in some studies it's obvious that the vehicle is different from the active formulation not only in active ingredient content.For example in a key study for anti-wrinkle efficacy of adenosine (20), it is said “A placebo cream known from previous studies to have no effect on wrinkles was used as control.” Even if ignore the fact that this previous study is not specified here, why do we think that using a completely different vehicle formulation (even with proven zero efficacy on the wrinkles) is fundamentally wrong?Because it's not about the efficacy of a vehicle, we agree here that it can be zero. It's about the efficacy of other ingredients in a formulation containing 0.1% of adenosine. How do we know that this formulation reduced wrinkles (no doubt about it) because of adenosine and not because of glycerin, mineral oil and other moisturizing ingredients it could have contained?There is no way to know that unless we also see the results of exactly the same formula with glycerin, mineral oil but without adenosine.It may be obvious that the active formulation and a vehicle should be used the same way, the same number of times per day, on the same part of the face (in case of the spit face study, on the symmetrical part of the face).But again, we see studies where it's not the case: otherwise a perfect study, that met all our criteria, confirming the anti-wrinkle efficacy of bakuchiol (21) on par with retinol, failed on delivering the equal and comparable conditions for an active and its positive control. According to the study design “the subjects were instructed either apply 0.5% retinol cream to their full face nightly or the 0.5% bakuchiol cream to their full face twice daily as a thin layer.”So we compare here 2 exactly the same formulas with only difference of active ingredients, which is great. But why one should be used twice a day and the other one just once? Is it because of bakuchiol that bakuchiol containing formula achieved the same results as the retinol one or because it was used twice more often and delivered better moisturizing reducing wrinkles? No way to know…In conclusion, we found that around a half of the studies reviewed, claiming anti-wrinkle efficacy are not vehicle/placebo/positive controlled. We don't talk here about rare ingredients but actually about the well known ones like trendy peptides or ascorbic acid derivatives. So that was a big exclusion factor.5. Double-blind
6. Randomized
7. Monotherapy - only one active with known concentration per formulation
For example, in a vehicle-controlled, double-blind, randomized study for Copper Tripeptide-1 (23) that meets all other criteria, the concentration of the peptide used was not reported.
Normally, peptides are used in tiny quantities, so we could have assumed a concentration of 0.1%. However, if a larger concentration was used, it would not be a fair and correct assumption.
8. Conclusive results of the study
Results should be measured by a researcher, not by a participant. Method of evaluation can be objective (profilometry, computer image evaluation) or subjective, in this case by trained experts/dermatologists (wrinkle severity gradual evaluation), but we don't take into consideration studies where participants' self-assessment of wrinkle improvement is the only result reported.
As Johann W. Wiechers wrote in his book Memories of a Cosmetically Disturbed Mind “Questionnaires can be leading, sometimes even misleading. Tell a person s/he is testing antiwrinkle products and any product will work (to some extent).” (22)
Result should clearly report wrinkle reduction: various parameters like wrinkle depth, surface roughness (Ra, Rz), wrinkle volume, clinical assessment score improvement, etc. Some studies just report a percentage of participants that improved wrinkling or overall photodamage score.
Result should be reported as mean score of a group of all participants and not just for some individual participants. It is not rare when effects are reported for a few subjects and then they are called “typical”.
Result should be reported as percentage of wrinkle reduction vs baseline or we should be able to calculate it with the data reported. It's often a case when results are reported as change of a certain wrinkle parameter vs. baseline (before treatment) in absolute value without precising what baseline value was. In this case we understand that there was a certain effect, we may even make a conclusion this effect was superior to placebo/vehicle, but we can't understand how significant it was.
For example, if a study reports that average skin roughness improved by 10 points, it can be a significant 20% improvement if the baseline value before treatment was 50 or it can be only 5% improvement if the baseline value was 200.
Both vehicle and placebo numbers are reported. We need to understand how the active formula vs. placebo/vehicle (see why in Chapter 4). Often, in a placebo-controlled studies, some results are reported only for an active formulation. Results of placebo/vehicle either are not reported at all or reported without any numbers saying something like “It (active) was statistically significant while vehicle was not”.
It doesn't necessarily mean that the researched ingredient is ineffective, probably it showed some level of efficacy, it's just we don't know what exactly, based on the data provided - because a researcher team didn't make it crystal clear when reported the results.
The other examples when data is reported only for active treatment in a format “improvement vs. baseline vs. placebo”. It may seem a valid format, but there is an important nuance and we've seen it in the study.
Let's say an active formula reduced wrinkles by 5%. At the same time subjects using placebo/vehicle formulation, got their wrinkles worse by 10%. It's quite unusual as normally vehicle/placebo has a positive effect on wrinkles, but in a few studies we've seen this case, probably because of the low moisturizing properties of the vehicle.
So the researchers motivated to demonstrate the efficacy of an active treatment, report that an active has decreased the wrinkles by 15% vs. placebo/vehicle, which is mathematically correct. It's just the wrinkle were reduced only by 5% and that's the number we record as the efficacy result of this ingredient. That's why we need to see a transparent reporting of both results for active and vehicle.
9. Peer reviewed
Conclusion
About the author
References
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