Patients saw stretch-mark gains; blinded doctor didn't

Mature stretch marks, known as striae albae, are the pale, settled form that most people are left with long after the marks first appear. They are extremely common and notoriously resistant to treatment, because they are essentially dermal scars rather than superficial pigmentation. Topical retinoids like tretinoin struggle to penetrate deeply enough to reach the affected dermis. Fractional radiofrequency creates microscopic channels in the skin and could in principle act as a permeation enhancer, letting a topical drug get where it needs to go. This trial tested whether pairing the two beats either alone.

Twenty patients were enrolled, and rather than comparing people against each other, each patient provided four anatomically comparable areas of striae that were randomised to topical tretinoin alone, fractional radiofrequency alone, the combination of both, or no treatment as a control. Three treatment sessions were delivered one month apart, with tretinoin also applied in the intervals between sessions. The primary measure was the change from baseline to a 20-week follow-up on the Patient Observer Scar Assessment Scale, scored from 6 to 60. Assessment came from the patients themselves, from a blinded dermatologist, and from objective 3D photography.

At baseline patients rated their striae as moderate to severe, with POSAS patient SUM medians of 24 to 25. By follow-up all treated areas showed some patient-reported improvement, with change scores of 5 to 10 points, but only the combination of fractional radiofrequency plus tretinoin improved significantly more than the untreated control (p = 0.029). The blinded dermatologist's scores moved far less, with change of 0 to 2 points and no treatment reaching significance against control (all p ≥ 0.269). The 3D photographic measures showed only a subtle tendency in the same direction. Treatment was reported as tolerable.

The result is consistent with the general picture that striae albae are hard to shift and that no existing monotherapy reliably clears them. It offers some support for the permeation-enhancer rationale, since the combination outperformed either component alone against control, but the gap between what patients perceived and what a blinded assessor could see is the crucial caveat. Unblinded self-assessment of a treated versus untreated patch is vulnerable to expectation. Whether the combination produces changes large enough to be visible to anyone other than the person being treated, and whether more sessions or longer follow-up would widen the difference, remains unanswered.

This is a reason to keep expectations modest about stretch-mark treatments generally, and to notice how much the answer depends on who is doing the rating. A combination approach looks more promising than either radiofrequency or a topical retinoid on its own, and it was tolerated, but the objective and blinded measures did not confirm the patient-reported gain. Anyone reading marketing claims about device-plus-cream protocols should ask whether the improvement was assessed by the patient or by an independent blinded observer, because in this trial those two answers diverged.