Roughly One in 190, and Ten Years to Get the Name

It starts as a painful lump in the armpit, the groin, under the breast, along the inner thigh. It comes and goes. Then it comes back in the same place, and the place after that, and eventually the lumps connect underneath the skin into tunnels that drain.

Hidradenitis suppurativa is not an infection, not a hygiene failure, and not a series of boils — and it gets treated as all three for the better part of a decade before anyone names it.

Who has it

The best US population figures come from Garg and colleagues, working from electronic health records covering more than 48 million patients. Overall standardized prevalence: 98 per 100,000. Women 137, men 58. Highest in the thirties.

By race, adjusted: African American 296 per 100,000, biracial 218, white 95. Roughly three times and twice the white rate.

Then the pediatric paper, same data source, and the figure that should be better known than it is. Overall pediatric prevalence 28.1 per 100,000. Girls, 44.6. Ages fifteen to seventeen, 113.7.

African American girls aged fifteen to seventeen: 525.1 per 100,000, confidence interval 459 to 598.

Roughly one in 190 carries a coded diagnosis. In the age group where a chronic, painful, scarring disease of the armpits and groin arrives in the middle of secondary school.

And the authors’ own limitation matters here more than most: patients who went undiagnosed were not captured, so the estimates may be underestimates. Which brings us to the reason they are.

One figure to retire while we are here. A great many papers open by stating HS affects about 2 percent of the population. That is roughly twenty times the coded US estimate, and it comes from European survey and self-report studies with completely different ascertainment. The defensible framing is that coded US prevalence sits near 0.1 percent, survey estimates run much higher, and the truth is somewhere between because of the delay.

Seven to ten years

The anchor numbers in the field: 7.2 years plus or minus 8.7 in an international study, 8.4 in a French national cohort, 10.0 plus or minus 9.6 in a German one, and 10.1 in a Portuguese population with no improvement across seventeen years of observation.

The German study, 394 patients, gives the clearest picture of what those years contain. Patients consulted on average more than three different physicians — general practitioners first, then dermatologists, then surgeons, then gynecologists — and collected on average more than three misdiagnoses before someone got it right.

The French study, 312 patients across sixteen centers, counted the doctors. Fifty-four percent had seen at least three general physicians before diagnosis. Thirty-seven percent had seen at least five. Fifteen percent had seen ten or more.

Mean time from first signs to a first dermatology appointment: 6.2 years. To a definitive diagnosis: 8.4.

The surgical detour is the one that does damage. A painful fluctuant lump in an armpit reads as an abscess, and an abscess gets incised and drained. That is correct management for an abscess and it is the wrong operation for HS, which will refill and scar. The PIONEER trial authors write it plainly: HS is commonly misinterpreted as an infection and treated with long-term antibiotics or surgical incisions.

The disparity survives the usual explanations

The obvious objection to any racial gap in a disease associated with obesity and smoking is that it is really a gap in obesity and smoking. One study has actually tested that.

Ulschmid and colleagues reviewed 1,190 patients with at least three HS encounters at a single Wisconsin center and analyzed 953 — 49 percent Black, 44 percent white. Then they adjusted for age, sex, BMI, tobacco use and insurance type.

Hurley stage III disease, the most advanced category: odds ratio 2.80, interval 1.76 to 4.45.

Emergency department visit for HS: relative risk 2.86.

Hospitalization for HS: 2.25. Surgical encounter: 1.61.

All against white patients, all after adjustment for the confounders usually offered instead. Single center in Milwaukee, and a 49 percent Black HS cohort is not nationally representative — the local emergency department landscape is doing some of that work. But this is the study to put in front of anyone who explains the gap away with body weight and cigarettes.

A separate analysis of 2,265 patients in the NIH All of Us database found African American patients had significantly higher rates of emergency department visits, diabetes, complex surgeries and inability to afford medications. That last one is the mechanism connecting the first three.

And in a survey of 1,040 patients across six continents, 15.2 percent said they believed they would receive better care if they were of a different race, and 13.6 percent said their primary HS provider had treated them unfairly on the basis of race. Minority participants reported both more often. Self-selected online sample, so it measures experience rather than incidence — but experience is the thing that determines whether someone goes back.

The drugs, against the endpoint they are scored on

First, the endpoint, because every number below is meaningless without it. HiSCR means at least a 50 percent reduction in abscess and inflammatory nodule count, with no increase in abscesses and no increase in draining tunnels. It is a half-better endpoint, not clearance. And the placebo response in these trials runs 26 to 34 percent, which is high.

Adalimumab, the two PIONEER trials, 633 patients. Week 12: 41.8 percent against placebo 26.0 in PIONEER I, and 58.9 against 27.6 in PIONEER II. Real effects — but PIONEER I failed its rank-ordered secondary endpoints, including pain, while PIONEER II passed. Two identically designed trials, and they did not replicate on the outcome patients care about most.

Maintenance is sobering. Among patients who responded at week 12, the proportion still responding at week 36 was 48.1 percent on weekly dosing, 46.2 percent stepped down, and 32.1 percent withdrawn to placebo. Fewer than half of responders were still responders six months later, and a third of the placebo group held on anyway.

Secukinumab, SUNSHINE and SUNRISE, over 1,000 patients across 40 countries. Week 16 HiSCR: 45 and 42 percent for the two dosing arms in SUNSHINE against 34 percent placebo; 42 and 46 in SUNRISE against 31. The every-four-weeks dose missed significance in SUNSHINE and was the best-performing arm in SUNRISE. Same dose, two identical trials, discordant results. All patients also used daily topical antiseptics, which is add-on design and inflates the placebo arm.

Bimekizumab, BE HEARD I and II, over 1,000 patients. Week 16: 48 percent against 29, and 52 against 32. Oral candidiasis is the expected class effect of blocking both IL-17A and IL-17F and appeared among the most frequent adverse events in the second trial.

Do not rank these three against each other. They were never compared head to head, they used different timepoints, different imputation methods and different background therapy rules. The only defensible statement is that all three beat placebo by somewhere between eight and thirty-one percentage points on a fifty-percent-improvement endpoint.

And none of them has published race-stratified efficacy data. In a disease whose highest-prevalence group in the United States is Black adolescent girls.

Surgery, and the instability in the numbers

Wide excision beats local excision, and that is consistent. A 2021 meta-analysis of 33 studies put pooled recurrence at 8 percent for wide excision and 34 percent for local.

Reconstruction is where the evidence wobbles. The same 2021 analysis reported 0 percent recurrence with flap repair, confidence interval 0 to 4. A 2025 network meta-analysis of 121 studies reported 12 percent, interval 9 to 15.

Those intervals do not overlap. Two meta-analyses of overlapping literature, arriving at incompatible answers for the same operation. A pooled zero percent with a four-point ceiling is the signature of small, selected case series with short follow-up rather than a cure. Use the conservative set: flaps 12 percent, grafts 18, primary closure 25, secondary intention 28.

Metformin gets recommended a great deal. The evidence is one open-label uncontrolled single-arm study of 25 patients, in which 18 improved. With a placebo response of 26 to 34 percent in the controlled trials, an uncontrolled 72 percent improvement rate is not interpretable as a drug effect. I could not find a randomized placebo-controlled trial of metformin in HS. If someone cites one, ask for the registration number.

The comorbidity conversation, handled honestly

HS is associated with metabolic syndrome. The most conservative estimate, from five studies and 3,950 patients, is an odds ratio of 1.82 with metabolic syndrome present in 9.64 percent of HS patients. A case-control meta-analysis put it at 4.46. Case-control designs inflate effect sizes; prefer the lower figure, and if you see the higher one quoted alone, that is a choice somebody made.

Smoking is the other standard association, and a 2026 analysis of two Danish cohorts did something useful with it. Current smoking was associated with more severe disease — Hurley III odds ratio 2.38 — but the dose-response between pack-years and severity vanished after adjusting for age and sex.

Then the finding nobody quotes. Smoking cessation and smoking initiation both showed a trend toward increased self-reported severity at twelve months. Both directions. The authors call it limited and exploratory and still conclude cessation should be part of management, which is reasonable. It is also a reason not to promise anyone that quitting will clear their HS quickly, because the one dataset that looked did not find that.

And a Cutis review of a predominantly Black surgical HS population found low rates of cigarette smoking and high rates of marijuana use — which complicates the reflexive framing of HS as a smoker’s disease when applied to Black patients.

One number to keep in perspective. The headline that HS raises your risk of death rests on a cohort where crude five-year mortality was 2.4 percent in HS patients against 2.7 percent in controls — lower, because HS patients are younger. Only after full adjustment does an odds ratio of 1.14 appear, with the lower confidence bound at 1.01, and an excess absolute risk of 3.1 deaths per thousand with an interval starting at 0.2.

The thing that changes the trajectory

Getting the diagnosis. In a database comparison of 3,065 adults with confirmed HS against 27,280 with suspected HS, the confirmed group started biologics faster, had fewer hospitalizations, fewer emergency visits, more outpatient care, and about $14,200 lower costs per patient.

Note that ratio on its own: nine patients circulating with suspected HS for every one confirmed.

So the practical thing, and it is unglamorous. If lumps keep coming back in the same folds — armpits, groin, under the breast, between the thighs — say the words hidradenitis suppurativa at the appointment. Ask whether this could be that. Ask before agreeing to another incision and drainage, because that procedure is correct for an abscess and counterproductive for this.

Three physicians and three wrong answers is the average. Knowing the name is how you skip some of them.

This article is educational and is not a substitute for care from someone who can look at your skin. Anything new, changing, painful or spreading should be assessed rather than researched.