Posture
How we use evidence
Evidence is necessary but not sufficient. We use the literature to anchor decisions, clinical judgment to apply them to the patient in front of us, and honest reassessment to change course when something is not working.
This page lists the studies we lean on, summarizes what each one tested, and is explicit about what it does and does not establish. A page that pretends the evidence is settled when it isn't loses the audience it should be earning.
Evidence base
Follicle-directed laser therapy
Long-pulsed Nd:YAG (1064 nm) is the most-studied device in HS. The trials below establish a real effect on lesion burden and a mechanistic basis at the follicular level.
- What it tested
- Long-pulsed Nd:YAG against control (treated vs untreated body sites in the same patient).
- What it found
- Significant reduction in modified Hidradenitis Suppurativa Lesion Area and Severity Index across treated sites.
- What it does not establish
- Single-center, short follow-up, intra-patient design. Establishes a real effect, not long-term durability.
- What it tested
- Long-pulsed Nd:YAG monthly for four months in Hurley I–II HS, with paired untreated control sites.
- What it found
- Statistically significant reduction in disease severity at treated sites versus untreated controls.
- What it does not establish
- Modest sample, four-month treatment window. Does not address Hurley III or established tracts.
- What it tested
- Pre- and post-treatment biopsies of HS-affected skin to characterize histologic changes after Nd:YAG therapy.
- What it found
- Reduction in follicular and perifollicular inflammation and folliculosebaceous unit destruction.
- What it does not establish
- Mechanistic, not outcome-based. Supports why follicle therapy works; does not measure clinical response.
Evidence base
CO₂ laser tunnel closure and deroofing
The CO₂ laser literature spans decades, from Lapins's foundational technique to the modern tissue-sparing deroofing framework. Recurrence in treated tracts is uncommon; recurrence in adjacent untreated skin is the field-not-tract problem.
- What it tested
- CO₂ laser stripping of HS-affected tissue with healing by secondary intention in a consecutive series.
- What it found
- Effective local control of disease in treated areas, with the secondary-intention model establishing the recovery template still used today.
- What it does not establish
- Series, not a trial. The foundational paper for CO₂ closure technique rather than a definitive efficacy study.
- What it tested
- CO₂ laser excision in nine patients with severe, medically refractory HS.
- What it found
- Sustained local control in the treated regions on follow-up, with recurrence largely confined to untreated adjacent skin.
- What it does not establish
- Small series. Supports the regional-treatment model — disease tends to come back in the field you didn't treat, not in the field you did.
- What it tested
- CO₂ laser excision and marsupialization in 185 patients across multiple anatomic regions.
- What it found
- Low local recurrence at treated sites across a large series; technique well-tolerated with manageable recovery.
- What it does not establish
- Single-center, retrospective. Outcome measures differ from the standardized scales used in more recent work.
- What it tested
- Deroofing of HS sinus tracts and abscesses (88 patients, 414 lesions) with long-term follow-up.
- What it found
- Recurrence at the deroofed lesion was 17% at a mean follow-up of 34 months; high patient satisfaction.
- What it does not establish
- Deroofing is the conceptual cousin of CO₂ closure — same principle of preserving healthy tissue and treating the tract. Establishes durability of the tissue-sparing approach.
Mechanism
The disease model
Why follicle therapy is rational rather than empirical. HS begins at the hair follicle — not the apocrine gland — and the downstream inflammation and tract formation flow from that initiating event.
- What it tested
- Histopathology of early HS lesions to characterize where inflammation begins.
- What it found
- Earliest inflammatory changes localize to the terminal hair follicle and immediately adjacent epidermis.
- What it does not establish
- Establishes the follicular origin of HS — the mechanistic basis for follicle-directed therapy being rational rather than empirical.
- What it tested
- Histopathologic review arguing HS originates in the hair follicle, not in apocrine glands.
- What it found
- The apocrine-gland model is historically incorrect; the disease is follicular in origin.
- What it does not establish
- Naming polemic, but the underlying point — that HS is a follicular, not glandular, disease — is now widely accepted and frames why follicle therapy makes sense.
The honest limits
Where the evidence is still thin
- There are no large head-to-head randomized trials comparing follicle-directed laser, CO₂ tunnel closure, deroofing, and wide excision in the same patient population. Choice of procedure is driven by Hurley stage, anatomy, and clinical judgment — not by a comparative trial that resolves the question definitively.
- Outcome measures in HS studies are heterogeneous. HiSCR, Sartorius score, IHS4, and modified HSSI are not interchangeable, and effect sizes are not directly comparable across studies that use different scales.
- Long-term registry data on laser approaches at five and ten years is sparse. We follow patients clinically and document outcomes; the field still needs more multicenter long-term data.
- The literature underrepresents anatomic subgroups. Perianal and gluteal disease are studied less than axillary disease, even though they carry the highest recovery burden.
- Patient-reported outcomes — pain, function, quality of life — are improving in HS research but remain underweighted relative to lesion counts. We weight them at consult regardless of what the literature emphasizes.
The framework we work within
Clinical guidelines
The North American and European guidelines frame HS as a multimodal disease requiring staged medical and procedural care. Our program is built inside this framework, not adjacent to it.
- What it tested
- Consensus methodology synthesizing the available evidence on diagnosis and management of HS.
- What it found
- Multimodal care framework: topical and systemic medical therapy, procedural and surgical options, and management of comorbidities.
- What it does not establish
- Guideline, not a trial. The framework this site operates within for staging-matched, multimodal care.
- What it tested
- European consensus guideline on HS classification and stepwise treatment.
- What it found
- Recommends staged, multimodal care; explicitly includes laser and surgical approaches alongside medical therapy.
- What it does not establish
- S1-level (consensus, not systematic review). Complements the North American guideline.
Review
When this page changes
This page is reviewed periodically and whenever a clinically meaningful new study lands. The current version was reviewed on .
If you are a clinician with a reference you think we should add or replace, please write us. We take the suggestion seriously.