Microdermabrasion: its firmest randomised trial was not about its own effect, but about preparing skin for another treatment

A 2017 trial in JAMA Dermatology, at Bispebjerg Hospital, University of Copenhagen.

12 healthy volunteers aged 18 and over (8 men, 4 women, mean age 33) took part in an intraindividual randomised clinical trial — different preparations on different areas of the same person's skin.

Six things were compared.

• curettage
• microdermabrasion with abrasive pads
• microneedling with dermarollers
• ablative fractional laser (AFXL)
• non-ablative laser
• no pretreatment

The histology is what this entry is about.

The paper confirms histologically that the interventions were standardised, and what it found was this:

• after curettage and microdermabrasion, the stratum corneum was 'partially' removed
• microneedling, AFXL and non-AFXL had similar vertical penetration depths (median 125 µm)

Put those two lines side by side. They do different kinds of thing.

Microdermabrasion takes the outermost layer off broadly, shallowly and partially; the other three make holes downward in a pattern. They sit under the same word 'pretreatment', but what happens in the skin is not the same.

That is why this entry comes first on the page. The way this procedure gets described is usually 'it removes dead skin', and what histology confirmed is 'partially'. That word is the most accurate thing anyone can say about it — shallow, incomplete, and therefore quick to recover from.

But it is 12 people, and healthy skin. Different from the skin of people who actually go for this.

So it sits at 'early evidence'.

The primary endpoint of the same trial.

After each area was prepared, methyl aminolevulinate was left on for three hours and then illuminated with red light. What was measured is the accumulation of protoporphyrin IX (PPIX) fluorescence — how much of the drug was made inside the skin.

Results (medians, arbitrary units):

• ablative fractional laser — 8661
• microdermabrasion — 6731
• microneedling — 5609
• curettage — 4765

The differences among these four were significant (P < .001), and among them microdermabrasion, microneedling and curettage showed similar enhancement.

And the lower end:

• non-ablative laser — 2898
• drug-only control — 2254
• untreated — 239 (P < .03)

Two more things reported alongside:

• raising laser density (2%, 4%, 6%) or the number of pretreatment passes (1, 2, 3) did not increase PPIX fluorescence further
• local skin reactions were most intense on ablative-laser-pretreated skin, and correlated with PPIX fluorescence and the degree of photobleaching

How to read it.

First, this is not a result about wrinkles or texture. To say it again — what was measured is how much drug got in. This trial did not ask how this procedure changes a face.

Second, the numbers still place it. Microdermabrasion sits well above doing nothing (239), above applying the drug alone (2254), and below ablative laser (8661). That is: it does something, and it is not the strongest way to do it.

Third, the three being similar is practically useful. Microdermabrasion, microneedling and curettage came out alike. But those three differ in how much they hurt and how long recovery takes. The price of the same amount is not the same.

Fourth, doing it harder did not get more in. Raising laser density and the number of passes did not raise PPIX. 'Stronger and more often' is not always better — worth recording, because the same trial showed it.

Fifth, 12 people.

So it sits at 'early evidence'.