BackgroundHidradenitis suppurativa (HS) is a chronic, debilitating inflammatory skin disease. In Germany, there are no population‐based data on the epidemiology of HS.ObjectivesThe objective of this study was to examine the occurrence of HS in inpatient as well as in outpatient settings.MethodsWe used three data sources for analysing the prevalence, incidence and case‐related occurrence of HS in different settings: data of two German statutory health insurance (SHI) companies and hospital discharge data provided by the Federal Statistical Office. The studied period was from 2010 to 2015.ResultsIn a representative sample of about 2.3 million insurees (out of 5.9 million total persons) of the SHI DAK‐Gesundheit, 791 were diagnosed with HS in 2010. This coding prevalence of 0.03% is in accordance with the data of another SHI (Barmer) on about 9 million total insurees. In 2015, at least 34.7% of incident persons with HS had one potential misdiagnosis in 2014.ConclusionThis population‐based study analyses the prevalence and incidence of HS in Germany. The coding prevalence of 0.03% observed in two independent SHI data sets is lower than expected. The findings of considerable potential misdiagnosis add to the underdiagnosis of HS in general and underline the need for future strategies to early detection and valid diagnosis of HS.

Background There are currently no published population-based data on prurigo and pruritus epidemiology in Germany.Objectives We present the prevalence, incidence and comorbidity frequency of prurigo and pruritus in Germany. Methods This was a retrospective healthcare research study based on anonymized routine data from the German health insurance company DAK-Gesundheit. Evaluations were carried out for 2 006 003 adults who were insured as of 31 December 2010. Prurigo and pruritus diagnoses were based on International Classification of Diseases, Tenth Revision, German Modification (ICD-10-GM) codes. ResultsPrevalence was determined to be 0.21% (adjusted for sex and age 0.19%) for prurigo and 2.21% (adjusted 2.14%) for pruritus in 2010. The adjusted rates extrapolated to the total German population in 2010 show that 130 685 adults would have received a prurigo diagnosis and 1 461 024 a diagnosis of pruritus. In 2011, incidence of new prurigo and pruritus cases was 0.13% (adjusted 0.12%, extrapolated 77 263 cases) and 1.51% (adjusted 1.46%, extrapolated 978 885), respectively. Adults with prurigo suffered most frequently from hypertension (35.16%), hyperlipidaemia (24.95%) and depression (21.97%); all were reported more frequently in patients with prurigo compared with the general population (P < 0.001). Similarly, adults with pruritus suffered most frequently from hypertension (31.28%), hyperlipidaemia (23.52%) and depression (18.91%) compared with patients without pruritus (P < 0.001).Conclusions Our data show that prurigo is a relatively rare but significant disease and that pruritus is frequent and very variable in appearance, and both have a high comorbidity burden.

Summary Background Palmoplantar pustulosis (PPP) is a chronic pustular skin condition on the palms and soles. The disease is often seen in combination with plaque psoriasis, and whether PPP is a variant of psoriasis has been debated. The disease prevalence of PPP and co‐occurring psoriasis is not yet established and the patient group remains understudied. Objectives To estimate the prevalence of PPP and co‐occurring psoriasis in three population‐based cohorts and to provide information on patient demographics and characteristics. Methods Administrative healthcare registries and insurance databases from the U.S.A., Denmark and Germany were used as data sources. Patients with PPP were defined by a single International Classification of Diseases 10th Revision code for PPP during a 1‐year period. Information regarding co‐occurring plaque psoriasis and other comorbidities was extracted. Furthermore, use of antipsoriatic medication was identified. Results In total 1435, 751 and 1832 patients with PPP were identified in the U.S., Danish and German populations, with estimated 1‐year prevalences of 0·009%, 0·005% and 0·08%, respectively. Plaque psoriasis was present in 14·2–61·3% of patients with PPP. Patients with co‐occurring psoriasis had an overall higher prevalence of psoriatic arthritis. Similarly, medication use was more prevalent in patients with PPP with co‐occurring psoriasis, and especially pronounced was the use of biologic therapies. Conclusions This large observational study on patients with PPP provides detailed information regarding patient demographics, comorbidities and medication use. The 1‐year prevalence of PPP varied in the three studied populations, possibly due to differences in diagnostics and recording practices. Psoriasis frequently co‐occurred in patients with PPP. What's already known about this topic? Palmoplantar pustulosis (PPP) is a skin disease of the palms of the hands and soles of the feet and is known to be related to psoriasis. Whether PPP is a distinct disease or a variant of psoriasis is not yet established. The condition is understudied in terms of disease prevalence, disease predictors, patient characteristics and comorbidity. What does this study add? In this study using data from three large population‐based cohorts we found low prevalence rates (< 0·1%) of PPP. The prevalence of psoriasis was estimated at between 14·2% and 61·3% in patients with psoriasis. Patients with PPP with co‐occurring psoriasis have a higher prevalence of psoriatic arthritis and use of antipsoriatic drugs.