Christensen, Robin

Importance Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a substantial burden. Standardized global prevalence estimates and data on associated sociodemographic and risk factors are lacking. Objective To estimate the global prevalence of HS and study differences in prevalence by age, sex, geographical location, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), smoking status, gross domestic product (GDP), and Human Development Index (HDI). Data Sources and Study Selection Included studies were conducted using the standardized Global Hidradenitis Suppurativa Atlas methodology with finalized data collection before May 19, 2023. Studies were required to use a population-based sampling method and conduct clinical confirmation of HS diagnosis following a screening questionnaire. Data Extraction and Synthesis Data were independently extracted from relevant studies by 2 reviewers (D.B. and C.E.M.) using a standardized form. Extracted variables included geographic location, age, sex, BMI (median and BMI >30), smoking status, HS prevalence estimates (with 95% CIs), GDP, and HDI. A proportional meta-analysis using a random-effects model was conducted on the included studies. Main Outcomes and Measures The primary outcome was the point prevalence of HS, confirmed by clinical examination. Secondary outcomes included differences in HS prevalence by sex, age, BMI category, smoking status, and country-level socioeconomic indicators (GDP and HDI). All outcomes were prespecified before data analysis. Results The sample included 22 743 participants, identifying 247 patients with HS, across 25 studies in 23 countries spanning 6 continents. The median proportion of female patients with HS was 55.6%, and the median age was 34.5 years. While the prevalence estimates showed considerable inconsistency ( I 2 > 75%; τ 2 = 0.747), the overall random-effects global prevalence of HS was 0.99% (95% CI, 0.67%-1.46%). Female sex was the only factor observed to be associated with the prevalence estimates (β = 1.02; 95% CI, 1.01-1.03). Conclusions and Relevance In this meta-analysis, an estimated global prevalence of HS between 0.67% and 1.46% surpassed previous global estimates. Substantial global variations in HS prevalence were also observed. Female sex was the only factor associated with prevalence in this sample. Future studies assessing genetic, environmental, and etiological factors are warranted to explain the heterogeneity in prevalence.

AbstractBackgroundThe popularity of the gluten‐free diet and sales of gluten‐free products have increased immensely.AimsTo investigate whether gluten induces gastrointestinal symptoms, measured by self‐reported questionnaires, as well as mental health symptoms in adolescents from a population‐based cohort.MethodsThe eligible participants (n = 273) were recruited from a population‐based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run‐in phase where the participants lived gluten‐free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross‐over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7‐day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed.ResultsIn total, 54/273 participants entered the run‐in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2–20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was −0.01 (95% confidence interval −2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health.ConclusionCompared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population‐based cohort. The trial registration number is NCT04639921.