Patients with Atopic Dermatitis and Insufficient Response to Conventional Systemic Therapy in Germany: A Health Claims Data Analysis

Abstract

Introduction

Atopic dermatitis (AD) is a prevalent, chronic, inflammatory skin disorder causing significant quality-of-life impairment. Some patients need systemic therapy depending on disease course and effectiveness of topical treatment. Current systemic treatments may have limitations for long-term use and/or for different patient age groups. This study investigates conventional systemic therapy use and indicators of insufficient disease control on the basis of German statutory health insurance health claims data.

Methods

This retrospective cohort study used claims-based data from the Institute for Applied Health Research Berlin GmbH (InGef) sample database from 1 October 2019 to 31 December 2022, with the index period defined as 1 October 2021 to 30 September 2022. The pre-index period was from 1 October 2019 to 30 September 2021, and the observation period was from 1 October 2021 to 31 December 2022. Patients diagnosed with AD (ICD-10-GM code L20.8 or L20.9) with continuous insurance during the index period were included.

Results

Of 4 million eligible patients in the InGef sample database, 3400 were eligible for systemic drug therapy. Of these patients, 1016 were treated with targeted systemic therapy, and 1719 treated with conventional systemic therapy had insufficient disease control. The overall 1-year administrative prevalence of AD was estimated at 2.4%, and the incidence of AD was estimated at 0.3%. Prevalence was highest in children aged ≤ 4 years (7.0%) and decreased with advancing age. The most prevalent criterion of insufficient disease control was AD-related infections, affecting 58.4% of patients, followed by prolonged use of topical treatment (44.2%) and frequent active flares (36.9%).

Conclusions

These findings highlight the challenges in managing AD with conventional systemic therapies and underscore the need for improved treatment strategies. Insights into the patterns of systemic therapy use and disease control can inform future therapeutic approaches and policy decisions to enhance patient outcomes in AD management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-026-01749-3.

Plain Language Summary

Atopic dermatitis is a skin disease that causes severe itching, pain, and trouble sleeping, and makes daily life harder. In Germany, about 4 out of every 100 people have atopic dermatitis. It is almost two times as common in people younger than 15 years of age than in the overall population. Patients with atopic dermatitis often need continuous treatment with medicines applied on the skin. Patients with moderate-to-severe disease may need additional treatment with medicines called conventional systemic therapies. These are types of medicines that decrease swelling and help your immune system. Some patients still cannot control their atopic dermatitis using these conventional systemic therapies. The purpose of this study was to identify patients in Germany who do not achieve good control of their atopic dermatitis with conventional systemic treatments. We looked at health insurance data from Germany and found that the most common signs of poor disease control with these treatments were atopic dermatitis-related infections (58 out of 100 patients). About 12 out of 100 patients who had insufficient disease control while using conventional systemic therapies had been hospitalized due to their atopic dermatitis. This study highlights that some patients do not respond well to conventional systemic therapies and may benefit from more advanced treatments that target atopic dermatitis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-026-01749-3.

Key Summary Points

Why carry out this study?

Atopic dermatitis (AD) is a prevalent, chronic, inflammatory skin disorder that frequently requires long-term treatment due to its relapsing nature; however, current systemic therapy treatment options may have limitations for long-term use or for patients aged ≤ 18 years.

The study aimed to identify the population of patients with AD treated with conventional systemic therapy in Germany and describe indicators of insufficient disease control within this group.

What was learned from the study?

The overall 1-year administrative prevalence of AD was estimated at 2.4%; prevalence was highest in the youngest age group (0–4 years) and decreased with increasing age.

AD-related infections were the most common indicator of insufficient disease control, followed by prolonged use of topical treatment and high number of active flares.

The study highlights the need for better characterization and understanding of systemic therapy use and disease control in patients with AD, particularly for those treated with conventional systemic treatments.

Introduction

Atopic dermatitis (AD) is a common chronic inflammatory skin disorder characterized by symptoms such as intense itch, pain, and sleep disturbances and a significant reduction in quality of life [1]. The prevalence of AD in the general German population is approximately 4.2%. AD is more common in children and adolescents aged < 15 years, with a prevalence of 9.4% compared with 5.5% in adolescents aged 15‒19 years and estimates ranging from 1.6% to 4.1% in adults aged > 19 years [2, 3]. The chronic relapsing/remitting nature of AD may necessitate long-term treatment [1, 4].

In Germany, topical agents are typically the first-line treatment; however, patients with severe AD or those for whom topical therapies are insufficient to control AD signs and symptoms may require systemic therapies [4–6]. Systemic agents approved for moderate-to-severe AD by the European Medicines Agency (EMA) include conventional systemics (e.g., oral glucocorticoids and cyclosporine) and biologics such as dupilumab (approved in 2017), tralokinumab (approved in 2021), lebrikizumab (approved in 2023), and nemolizumab (approved in 2025) [7–9]. Other EMA-approved systemic agents include Janus kinase inhibitors such as abrocitinib (approved in 2021), baricitinib (approved in 2020), and upadacitinib (approved in 2021) [10–12]. These treatments are, however, not without limitations; for example, some have limited indications or have only recently received approval for use in pediatric patients, who make up a substantial proportion of the AD patient population. Furthermore, oral glucocorticoids are not recommended for long-term use in adults but may be considered for acute treatment of flares, and they are unsuitable for children and adolescents except in rare circumstances [6]. Cyclosporine may be considered for interval therapy but has limitations for long-term use and should only be used in children and adolescents aged < 16 years in the case of contraindication or a lack of efficacy of approved systemic therapies [6].

The patterns of conventional systemic therapy use and indicators of insufficient disease control in German patients treated with conventional systemic agents are not well described in the literature. The objectives of this study were to identify the population of patients with AD treated with conventional systemic therapy in Germany and estimate the frequency of insufficient disease control in this population on the basis of six predefined indicators.

Methods

Study Design and Setting

Study Design

This retrospective cohort study used claims-based data from the Institute for Applied Health Research Berlin GmbH (InGef) sample database, which is a subsample of the InGef research database. The InGef research database comprises anonymized longitudinal and nationwide data from approximately 9 million insured persons across more than 50 German statutory health insurance (SHI) companies. The InGef sample database includes a subsample of almost 5 million individuals—approximately 5.5% of the SHI population—from the InGef research database and is intended to be representative of the German population in terms of age and sex distribution and measures of morbidity, mortality, and drug usage [13].

Setting

As the InGef sample database contains claims data from more than 50 nationwide SHI companies in Germany, there is no geographical restriction to inclusion of particular regions of Germany. This study included claims data covering the study period from 1 October 2019 to 31 December 2022 (Fig. 1). The population of patients with AD eligible for systemic drug therapy and the subpopulations of patients with AD treated with either targeted or conventional systemic drug therapy were identified for the index period (1 October 2021 to 30 September 2022). The pre-index period was defined as 1 October 2019 to 30 September 2021, and the observation period extended from 1 October 2021 to 31 December 2022.

Fig. 1.

Study design and analysis groups. ^aTopical corticosteroids, topical calcineurin inhibitors, or systemic drugs. ^bSystemic corticosteroids, cyclosporine, off-label drugs (azathioprine, methotrexate, mycophenolate mofetil; patients aged < 16 years: cyclosporine), dupilumab, baricitinib, tralokinumab, upadacitinib, abrocitinib. AD atopic dermatitis, Q quarter

Participants

Prevalent AD Population

Patients with AD were identified on the basis of a documented main or secondary hospital diagnosis or two confirmed outpatient AD diagnoses within two different quarters (defined by the International Classification of Diseases and Related Health Problems, Tenth Revision, German Modification [ICD-10-GM] code L20.8 or L20.9) during the index period and were classified as the prevalent patient population. In the prevalent AD population, only patients with continuous insurance or until death occurred during the index period were considered.

Incident AD Population

Patients from the prevalent AD population without any documented inpatient or outpatient AD diagnosis during the pre-index period were included in the incident patient population. To allow assessment of inclusion criteria for the incident AD population, patients required continuous insurance during the pre-index and index periods.

AD Patient Population Eligible for Systemic Drug Therapy

Patients were included in the population eligible for the systemic drug therapy subgroup if they had ≥ 1 dispensation of an AD-related moderate- to high-potency topical or systemic drug therapy (category 2 or 3; Table S1) during the index period and a dispensation of an AD-related systemic drug therapy (category 3; Fig. 1 and Table S1 [14, 15]) within the index period or 2 years prior; dispensations had to occur within the same quarter as a documented AD diagnosis. For these criteria to be assessed, patients were required to have continuous insurance during the pre-index, index, and observation periods (or until death occurred) and a diagnosis of AD during both the pre-index and index periods (per the criteria above) and to be a minimum of 2 years of age in the index period. Patients with a dispensation of a targeted systemic drug (category 3c-h) were classified separately.

AD Patient Classification by Type of Systemic Therapy

The population of patients eligible for systemic drug therapy was further stratified on the basis of whether they had a dispensation of a targeted systemic therapy (category 3c-h) during the pre-index or index period. As such, patients treated with targeted systemic therapy were assumed to have had inadequate disease control with conventional systemic therapy and were classified separately. Patients without a dispensation of a targeted systemic therapy were included in the subgroup of patients treated with conventional systemic therapy and were assessed for criteria of insufficient disease control.

Outcomes

Outcomes assessed in this study were administrative prevalence over a 1-year period and incidence proportion of AD during the index period. Insufficient disease control, operationalized by six predefined criteria, was analyzed during the index and observation periods (only applicable to criteria IV. High use of topical treatment and V. Prolonged use of topical treatment) in patients without a claim for a targeted systemic therapy during the pre-index or index period (i.e., patients treated with conventional systemic drug therapy). Further details on operationalization of the criteria are provided in Table S2.

Statistical Methods

The variables included in this study were calendar year, person identifier, age, sex, health insurance status, inpatient diagnosis, inpatient procedure, hospitalization, outpatient diagnosis, physician specialty, and drug prescriptions. The role of each variable, corresponding data sources, and operational definitions are listed in Table S3.

The InGef sample database comprises several claims-based datasets relevant to this study, which include the following:

• Core data including age, sex, and insurance status

• Inpatient data including diagnoses with exact dates of admission; main discharge and secondary (ICD-10-GM codes), diagnostic, and therapeutic procedure (operation and procedure) codes; dates of hospital admission and discharge; and costs

• Outpatient data including diagnoses related to a quarter (ICD-10-GM codes), diagnostic confidence (e.g., confirmed, suspected), diagnostic and therapeutic procedures (Einheitlicher Bewertungsmaßstab/Uniform Assessment Scale codes) with exact dates, and costs

• Outpatient drug prescriptions including the drug prescribed and dispensed (Pharmazentralnummer [can be mapped to ATC codes]), exact date of prescription and dispensation, and costs

• Sick leave and sickness benefits data including diagnoses (ICD-10-GM codes) related to the sick leave, exact dates of the start and end of sick leave and sickness benefit payments, and costs

The InGef sample database has been validated against national data regarding relevant indicators, which show that indicators of morbidity, mortality, and drug use are generally in good accordance with national data, indicating external validity of the database [13]. As this study had no a priori hypotheses and thus no planned confirmatory analyses, no sample size calculation was conducted.

All outcomes were stratified by age group. Systemic therapy subpopulations were also stratified by the quarter of the first observable dispensation of a systemic therapy combined with a documented AD diagnosis (hospital main or secondary discharge or confirmed outpatient diagnosis) during the index period or pre-index period. Patients with a claim for a targeted systemic therapy were also stratified by dispensed AD-related targeted systemic therapy. Patients treated with conventional systemic drug therapy and with signs of insufficient disease control were quantified by various combinations of disease control criteria. Position and dispersion (mean, median, minimum, maximum, SD) were reported. A sensitivity analysis of variation in outpatient specialist consultations is defined in Table S4. All outcomes were extrapolated to the SHI population (on the basis of data from the KM 6 statistics of the Federal Ministry of Health) and the German population (on the basis of data from the Destatis statistics of the Federal Statistical Office).

Ethical Approval

Because all patient‐level data in the database are anonymized to comply with German data protection regulations and German federal law, neither approval by an ethics committee nor patient consent were required. The research was conducted in accordance with the Declaration of Helsinki.

Results

Patient Populations

Of 4,728,945 patients in the InGef sample database, 4,194,029 were eligible for inclusion in the analysis, including 100,762 patients in the prevalent patient population and 9468 in the incident patient population (Fig. 2). A total of 3400 patients met the inclusion criteria for the patient population that was eligible for systemic drug therapy (Fig. 3 and Table 1). Of these, 1016 patients were included in the subgroup of patients treated with targeted systemic therapy. This extrapolated to 18,068 and 20,965 patients with AD who were treated with systemic targeted therapy in the SHI and German populations, respectively.

Fig. 2.

Patient flow for the prevalent and incident patient populations. AD atopic dermatitis

Fig. 3.

Patient flow for the patient populations eligible for systemic drug therapy. ^aHospital main/secondary discharge diagnosis. ^bAD-related medication (category 2 or 3): topical glucocorticoids (II–IV), topical calcineurin inhibitors (pimecrolimus, tacrolimus), and AD-related systemic therapies (category 3). ^cAD-related systemic therapies (category 3): systemic glucocorticoids, cyclosporine, and targeted systemic therapies (category 3c–3h). ^dTargeted systemic drugs (category 3c–3h): off-label drugs (azathioprine, methotrexate, mycophenolate mofetil; patients < 16 years: cyclosporine), dupilumab, baricitinib, tralokinumab, upadacitinib, abrocitinib. AD atopic dermatitis, Q quarter

Table 1.

Patient populations eligible for systemic therapy, stratified by age and sex

Subpopulation	Age group	Female	Male	Total
Patient population eligible for systemic drug therapy, n	Total, N	1853	1547	3400
	2–11 years	192	287	479
	12–17 years	58	68	126
	≥ 18 years	1603	1192	2795
Patients treated with targeted systemic therapy	Total, n	481	535	1016
	2–11 years, n (%)	11 (6)	13 (5)	24 (5)
	12–17 years, n (%)	25 (43)	21 (31)	46 (37)
	≥ 18 years, n (%)	445 (28)	501 (42)	946 (34)
Patients treated with conventional systemic therapy with insufficient disease control	Total, n	967	752	1,719
	2–11 years, n (%)	128 (67)	173 (60)	301 (63)
	12–17 years, n (%)	17 (29)	29 (43)	46 (37)
	≥ 18 years, n (%)	822 (51)	550 (46)	1,372 (49)

The majority of patients (n = 946 [93.1%]) receiving targeted systemic therapy were aged ≥ 18 years, while 2.4% (n = 24) and 4.5% (n = 46) of patients were aged 2–11 years and 12–17 years, respectively (Table 1). A further 2381 patients were included in the subgroup of patients treated with conventional systemic drug therapy (Fig. 3). This extrapolated to 41,161 and 48,467 patients with AD in the SHI and German populations, respectively. A substantial proportion of patients in this subgroup were children or adolescents; patients aged 2–11 years and 12–17 years made up 19.1% (n = 455) and 3.4% (n = 80) of the subgroup, respectively.

Prevalence and Incidence of AD in Germany

The overall 1-year administrative prevalence of AD was estimated at 2.4%. Prevalence was highest in the youngest age group (0–4 years [7.0%]) and decreased with advancing age (Fig. 4a). There were 1,764,254 and 2,076,701 patients with AD extrapolated to the SHI and German populations, respectively. The administrative incidence of AD during the index period was estimated at 0.3%. Incidence was highest in the youngest age group (0–4 years [1.5%]) and decreased with advancing age (Fig. 4b). There were 164,348 and 192,595 patients with newly diagnosed AD extrapolated to the SHI and German populations, respectively.

Fig. 4.

Estimated a) prevalence and b) incidence of AD in Germany by age and sex extrapolated to the SHI-insured and German populations. AD atopic dermatitis, SHI statutory health insurance

Characterization of Systemic Therapy Use in Patients Treated with Targeted Systemic Therapy

A total of 826 patients (81.3%) in the subgroup treated with targeted systemic therapy had the first observable dispensation of a targeted systemic drug during the pre-index period. Dupilumab was the most prescribed drug during the pre-index and index periods, followed by off-label drugs (Table 2). No patients in the subgroup treated with conventional systemic therapy with insufficient disease control had a claim for a targeted systemic therapy per the study design. Most patients (70.9%) in this subgroup had the first observable dispensation of a conventional systemic drug (i.e., systemic glucocorticoids or cyclosporine) prior to the fourth quarter of 2021, while 17.3% and 11.8% had the first observable dispensation between the fourth quarter of 2021 and the first quarter of 2022 and between the second and third quarters of 2022, respectively.

Table 2.

Frequency of individual drug dispensations in the subgroup of patients receiving targeted systemic therapy

	Pre-index period		Index period
	n	%	n	%
Off-label drugsa	138	13.6	129	12.7
Dupilumab	545	53.6	667	65.6
Baricitinib	47	4.6	73	7.2
Tralokinumab	9	0.9	56	5.5
Upadacitinib	6	0.6	76	7.5
Abrocitinib	0	0.0	12	1.2

^aAzathioprine, methotrexate, mycophenolate mofetil; patients aged < 16 years: cyclosporine

Insufficient Disease Control in Patients Treated with Conventional Systemic Therapy

Of patients treated with conventional systemic drug therapy, 1719 met ≥ 1 criterion for insufficient disease control (Fig. 3 and Table 1). This extrapolated to 29,526 and 34,826 patients with AD in the SHI and German populations, respectively. A substantial proportion of patients in this subgroup were children or adolescents; patients aged 2–11 years and 12–17 years made up 17.5% (n = 301) and 2.7% (n = 46) of the subgroup, respectively.

In patients with insufficient disease control, the most commonly met criteria across all age groups were AD-related infections (58.4%), followed by prolonged use of topical treatment (44.2%) and high number of active flares (36.9%) (Fig. 5a). Variation in outpatient specialist consultations (criterion I) was the least frequently met criterion in this population. A high number of active flares was present in combination with ≥ 1 additional criterion in 25.9% of patients, most often with AD-related infections (16.5%) (Fig. 5b). Measures of central tendency, position, and dispersion of criteria in patients treated with conventional systemic therapy with insufficient disease control are shown in Fig. S1.

Fig. 5.

Proportions of patients treated with conventional systemic drug therapy with insufficient disease control per a) individual insufficient disease control criteria and b) combinations of criteria. AD atopic dermatitis

When stratified by age, hospitalization due to AD was more frequent in children and adolescents (27.6% and 28.3%, respectively) than in adults (7.9%), whereas high use of topical treatment was less frequent in children (17.3%) compared with the other age groups, which ranged from 28.1% to 28.3% (Table S5). When stratified by the quarter of the first observable dispensation of a systemic drug, the most commonly met criterion across all timepoints was AD-related infections, followed by prolonged use of topical treatment and high number of active flares (Table S6).

Discussion

In this retrospective cohort study of claims-based data from the InGef sample database, the administrative prevalence and incidence of AD in Germany were estimated to be 2.4% and 0.3%, respectively. The highest rates were observed in children aged 0–4 years (prevalence, 7.0%; incidence, 1.5%), and rates consistently decreased with age. The prevalence rate observed in this study is notably lower than in a previous claims-based analysis in Germany, which estimated the 1-year prevalence of AD as 4.21% [2]. This discrepancy may be related to the ICD-10-GM codes used in the current study (L20.8 and L20.9), while the former study used the broader code L20, which includes L20.0 for Besnier prurigo [2].

Of patients who were eligible for systemic therapies, approximately one-third had a dispensation of a targeted systemic drug during the pre-index or index period. These results expand on an earlier study using German health claims data from 2017 in which administration of targeted systemic therapies was rare (dupilumab, 0.3%; off-label use of other drugs [i.e., azathioprine, methotrexate, and cyclosporine], ≤ 0.6%) [16] and on a 2019 study that demonstrated infrequent prescribing of targeted systemic therapy for German patients with AD in 2019 and identified 8151 prescriptions for dupilumab out of 1,263,857 total prescriptions for systemic therapies (6.7%) [2]. Although additional targeted systemic agents, including tralokinumab, baricitinib, and upadacitinib, received EMA approval for the treatment of moderate-to-severe AD during the pre-index period of the current study, only 6.1% of patients treated with a targeted systemic therapy had a dispensation of these drugs, while the majority of dispensations were for dupilumab and off-label use of other systemic drugs. The number of patients receiving targeted systemic therapies increased during the study period, although the uptake was low relative to the number of patients eligible for these treatments. While these findings suggest an increased acceptance of targeted systemic therapies among German clinicians relative to earlier analyses, together they identify a large population of patients who may benefit from treatment with these agents.

Among patients who only had dispensations of a conventional systemic therapy during the pre-index or index period, AD-related infections, prolonged use of topical treatment, and high number of active flares were the most commonly met criteria for insufficient disease control, regardless of age group. Insufficient disease control has a significant negative impact on health-related quality of life, work productivity, and everyday activity [15]. Together, these findings indicate a high disease burden in these patients and further support the use of targeted systemic therapies among patients eligible for systemic drug therapy.

Limitations

This study’s reliance on health insurance claims data presents several limitations. As the claims were recorded for administrative purposes, they are subject to miscoding and did not include patients from clinical trials or private insurance. The InGef database contains information gathered across multiple companies; therefore, a bias may exist relating to variation in data between different types of health insurance. However, since indicators of morbidity, mortality, and drug use in the InGef sample database are generally in good accordance with national data, indicating external validity of the database, biased estimates are unlikely. Over-the-counter drugs are not reimbursed by health insurance in Germany, and therefore these therapies were not captured in this analysis. Additionally, the analysis could not discern the type of physician who prescribed each drug or managed the care of patients. The study criteria did not identify patients as having moderate-to-severe AD (as no evaluation of disease severity was conducted by the clinicians) but instead narrowed down the patient population to candidates for systemic treatment. Furthermore, due to the short observation period, our study was only able to identify patients with AD who had a documented AD diagnosis within this time frame. This approach inherently excludes potential patients with AD who did not seek care for AD-related issues during the observation period and consequently had no recorded AD diagnosis. As a result, we may have failed to identify patients with less severe AD, leading to an underestimation of the true prevalence of AD. This limitation is a common challenge in annual prevalence estimations based on claims data. Finally, drugs that received EMA approval for the treatment of moderate-to-severe AD after the index period were not captured in this analysis, which may therefore not represent the current therapeutic landscape.

Conclusions

Together, these findings demonstrate a need in Germany for targeted systemic treatments for patients with moderate-to-severe AD, especially children and adolescents and those who have insufficient disease control with conventional systemic therapies. Understanding the reasoning behind insufficient disease control may help identify patients likely to benefit from targeted systemic therapy.

Supplementary Information

Below is the link to the electronic supplementary material.

Author Contributions

Carolina Schwedhelm: Interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Leonie Kunk: Study conception and design, interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Dorota Pawlowska-Phelan: Acquisition of data, data analysis, interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Olaf Behmer: Interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Anja Plenske: Study conception and design, interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Jessica Herrath: Study conception and design, interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Diamant Thaçi: Interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted, Agnes Kisser: Study conception and design, interpretation of data, writing – original draft preparation, writing – review and editing, final approval of the version to be submitted. All authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Funding

This study was sponsored by Pfizer Pharma GmbH, Berlin, Germany and the journal’s Rapid Service Fee was funded by Pfizer Inc.

Data Availability

The data used in this study cannot be made available in the manuscript or supplementary material or in a public repository due to the German Federal Data Protection Act (Bundesdatenschutzgesetz). The anonymized data used for this study are stored on a secure drive at InGef GmbH to facilitate the replication of the results. Access to the data used in this study can only be provided to external parties under the conditions of the cooperation contract of this research project and can be assessed upon request after written approval (info@ingef.de), if required.

Declarations

Conflict of interest

Carolina Schwedhelm, Leonie Kunk, Anja Plenske, Jessica Herrath, and Agnes Kisser are employees of Pfizer Pharma GmbH and may hold Pfizer stocks. Dorota Pawlowska-Phelan is an employee of InGef – Institute for Applied Health Research Berlin GmbH, which executes data analysis and manuscript preparation for IGES Institut GmbH. IGES Institut GmbH received funding from Pfizer. Olaf Behmer was an employee of Pfizer Pharma GmbH at the time of this study. Diamant Thaçi is a consultant, advisory board member, and investigator for Pfizer Inc., AbbVie, Almirall, Amgen, Beiersdorf, Bristol Myers Squibb, Boehringer Ingelheim, Celltrion, Fresenius, Eli Lilly and Company, Johnson & Johnson, LEO Pharma, NewBridge, Novartis, Regeneron, Sanofi, Sun Pharma, Takeda, Target RWE, UCB, and Vichy.

Ethical approval

Because all patient‐level data in the database are anonymized to comply with German data protection regulations and German federal law, neither approval by an ethics committee nor patient consent were required. The research was conducted in accordance with the Declaration of Helsinki.