
==== Front
Eur J Neurol
Eur J Neurol
10.1111/(ISSN)1468-1331
ENE
European Journal of Neurology
1351-5101
1468-1331
John Wiley and Sons Inc. Hoboken

39152571
10.1111/ene.16401
ENE16401
EJoN-24-0624.R1
Original Article
Headache
An interdisciplinary integrated specialized one‐stop outpatient clinic for idiopathic intracranial hypertension—a comprehensive assessment of clinical outcome
A comprehensive assessment of clinical outcome
Bsteh et al.
Bsteh Gabriel https://orcid.org/0000-0002-0825-0851
1 2 gabriel.bsteh@meduniwien.ac.at

Macher Stefan https://orcid.org/0000-0001-8068-1528
1 2
Krajnc Nik 1 2
Marik Wolfgang 2 3
Michl Martin 4
Müller Nina 1 2
Zaic Sina 1 2
Harreiter Jürgen 5
Novak Klaus 2 6
Wöber Christian 1 2
Pemp Berthold 4
1 Department of Neurology Medical University of Vienna Vienna Austria
2 Comprehensive Centre for Clinical Neurosciences and Mental Health Medical University of Vienna Vienna Austria
3 Department of Neuroradiology Medical University of Vienna Vienna Austria
4 Department of Ophthalmology Medical University of Vienna Vienna Austria
5 Division of Endocrinology, Department of Internal Medicine Medical University of Vienna Vienna Austria
6 Department of Neurosurgery Medical University of Vienna Vienna Austria
* Correspondence
Gabriel Bsteh, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18‐20, Vienna 1090, Austria.
Email: gabriel.bsteh@meduniwien.ac.at

16 8 2024
10 2024
31 10 10.1111/ene.v31.10 e1640106 5 2024
29 3 2024
19 6 2024
© 2024 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.
https://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Abstract

Background and purpose

Management of idiopathic intracranial hypertension (IIH) is complex requiring multiple specialized disciplines. In practice, this creates considerable organizational and communicational challenges for healthcare professionals and patients. Thus, an interdisciplinary integrated outpatient clinic for IIH (comprising neurology, neuroophthalmology, neuroradiology, neurosurgery and endocrinology) was established with central coordination and a one‐stop concept. Here, the aim was to evaluate the effects of this one‐stop concept on objective clinical outcome.

Methods

In a retrospective cohort study, the one‐stop era with integrated care (IC) (1 July 2021 to 31 December 2022) was compared to a reference group receiving standard care (SC) (1 July 2018 to 31 December 2019) regarding visual impairment/worsening and headache improvement/freedom 6 months after diagnosis. Multivariate binary logistic regression models were used to adjust for confounders.

Results

Baseline characteristics of the IC group (n = 85) and SC group (n = 81) were comparable (female 90.6% vs. 90.1%; mean age 33.6 vs. 32.8 years; median body mass index 31.8 vs. 33.0; median cerebrospinal fluid opening pressure 32 vs. 34 cmH2O; at diagnosis, visual impairment was present in 71.8% vs. 69.1% and chronic headache in 55.3% vs. 56.8% in IC vs. SC). IC was associated with a higher likelihood of achieving both headache improvement (odds ratio [OR] 2.24, 95% confidence interval [CI] 1.52–4.33, p < 0.001) and headache freedom (OR 1.75, 95% CI 1.11–3.09, p = 0.031). Regarding the risk of visual impairment and visual worsening IC was superior numerically but not statistically significantly (OR 0.87, 95% CI 0.69–1.16, p = 0.231, and OR 0.67, 95% CI 0.41–1.25, p = 0.354).

Conclusions

Interdisciplinary integrated care of IIH is favourably associated with headache outcomes and potentially also visual outcomes.

endocrinology
frequency
headache
idiopathic intracranial hypertension
impairment
neurology
neuroophthalmology
neuroradiology
neurosurgery
outpatient clinic
severity
vision
worsening
source-schema-version-number2.0
cover-dateOctober 2024
details-of-publishers-convertorConverter:WILEY_ML3GV2_TO_JATSPMC version:6.4.8 mode:remove_FC converted:20.09.2024
Bsteh G , Macher S , Krajnc N , et al. An interdisciplinary integrated specialized one‐stop outpatient clinic for idiopathic intracranial hypertension—a comprehensive assessment of clinical outcome. Eur J Neurol. 2024;31 :e16401. doi:10.1111/ene.16401
==== Body
pmcINTRODUCTION

Idiopathic intracranial hypertension (IIH) (formerly also referred to as pseudotumour cerebri or benign intracranial hypertension) is a syndrome of increased intracranial pressure of unknown aetiology [1]. Considered rare in the general population, IIH typically occurs in obese women of childbearing age with incidence increasing markedly due to the obesity pandemic [2, 3]. In addition to the risk of visual impairment, long‐term outcome is determined by disabling and often chronic headaches [4]. Once a diagnosis of IIH has been made, treatment goals are to preserve vision and alleviate headaches [5]. Treatment of IIH should include a combination of weight loss, pharmacological treatment and, in severe or refractory cases, invasive neurosurgical intervention [5, 6, 7]. Due to the increasing complexity of diagnosing, treating and monitoring patients with IIH, international consensus guidelines recommend that IIH care should be provided in specialized centres with access to the necessary resources and therefore recommend interdisciplinary management of IIH [8, 9]. Despite this broad consensus, there are very few descriptions in the literature as to how such interdisciplinary or multidisciplinary management should be structured and organized in practice.

An interdisciplinary integrated special outpatient clinic for IIH has recently been established at our centre providing a one‐stop approach to diagnosis and treatment. Although such one‐stop approaches are often promoted as a means of improving care, especially for chronic diseases with complex management, objective data on their outcome are very scarce. To date, there are no data on the explicit effects of interdisciplinary integrated care on the outcome of IIH.

The aim of this study was to describe the effects of specialized one‐stop interdisciplinary integrated care for IIH on clinical outcome parameters and to compare it with standard care.

METHODS

This study was designed as a retrospective cohort study by analysing the Vienna IIH (VIIH) database of the Department of Neurology, Medical University of Vienna, which is described in detail elsewhere [10]. As of 30 September 2023, the VIIH database contained a cohort of 289 patients with definite IIH according to the modified Friedman criteria [11]. VIIH case reports contain demographic data, details of diagnostic and therapeutic procedures as well as the course of IIH.

Study periods

Study periods covered the time from 1 July 2021 to 31 December 2022 for integrated care (IC) and 1 July 2018 to 31 December 2019 for standard care (SC). Two identical periods were chosen to minimize seasonal effects and the period from 1 January 2020 to 30 June 2021 was excluded to minimize direct and indirect influences of the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemic and the measures to combat the pandemic.

Intervention group: one‐stop specialized interdisciplinary integrated care

The interdisciplinary integrated IIH special outpatient clinic located at the Vienna General Hospital/Medical University of Vienna was established on 1 April 2021. Outpatient care is provided in the outpatient clinics of the Departments of Neurology, Neuroophthalmology and Endocrinology, and inpatient care at the Department of Neurology and, if necessary, in the Department of Neurosurgery (Figure 1). Appointments for examinations and treatment are coordinated through a central coordination by the Department of Neurology to take place at each department on the same day (‘one‐stop approach’) and communicated to patients in a clear and structured manner in writing. Referrals from specialists in ophthalmology or neurology with a (suspected) diagnosis of IIH are received centrally and reviewed within two working days by a specialist from the IIH special outpatient clinic and an appointment for the first examination is made according to urgency. Without referral from an ophthalmologist or neurologist, patients can present themselves independently or on referral from a general practitioner at the general neurology outpatient clinic, from where they can be referred to the IIH special outpatient clinic. Visits are scheduled to last at least 60 min doctor–patient contact (20 min for each of neurology, neuroophthalmology and endocrinology including ruling out secondary endocrinological causes of intracranial hypertension as well as dietology and weight management) for the first presentation and at least 30 min (10 min for each of neurology, neuroophthalmology and endocrinology) for check‐ups. The results of diagnostic processes and the choice of treatment options for patients of the IIH special outpatient clinic are discussed in a monthly interdisciplinary IIH board meeting chaired by neurology (comprising neuroophthalmology, neuroradiology, neurosurgery and endocrinology) and a joint recommendation is made based on the guidelines of the German Society of Neurology and local standardized operating procedures detailed elsewhere [10, 12]. Necessary prescriptions for drug therapies are requested and issued by the IIH special outpatient clinic and given or sent directly to the patient. For patients with language barriers, a professional interpreter (either in person or via a video interpreting service) is used for all visits. Patients remain in control in the IIH special outpatient clinic long term with check‐ups scheduled at intervals of 2 weeks to 6 months depending on the course of disease and individual necessity.

FIGURE 1 Structural process of the interdisciplinary integrative IIH outpatient clinic in Vienna.

Reference group—standard care

Standard care was assessed in the period before establishment of the IIH special outpatient clinic and required the patients to make appointments for clinical assessments, imaging and other instrumental examinations on their own without centralized coordination or comprehensive use of interpreters. Diagnostic processes and the choice of treatment generally followed the same standardized operating procedures as in the intervention group, apart from the use of glucagon‐like‐peptide‐1‐receptor agonists (GLP‐1‐RA) in patients with IIH and a body mass index (BMI) ≥30, which was introduced in March 2022.

Inclusion and exclusion criteria

All patients from the VIIH database with definite IIH according to the modified Friedman criteria and available follow‐up of ≥6 months were included. To avoid censored data, patients were excluded if the time from the first visit to the 6‐month follow‐up was either before the start or after the end of the defined time periods (1 July 2018 to 31 December 2019 or 1 July 2021 to 31 December 2022).

Outcome parameters and covariates

Clinical assessment included visual and headache outcome parameters and was determined 6 months after baseline, that is, the diagnosis of IIH. Visual impairment was defined as a visual acuity deviation of ≥0.1 logarithm of the minimum angle of resolution (log MAR; determined by Sloan tables at distance after subjective refraction) and/or <−2.0 mean deviation in decibels (dB) in the static threshold perimetry determined by the 30‐2 Swedish Interactive Threshold Algorithm (SITA) [13]. Visual worsening was defined as deterioration of visual acuity by ≥0.2 log MAR and/or by ≥2.0 dB in the static threshold perimetry compared to baseline at diagnosis [13]. Headache improvement was defined as a ≥50% reduction in headache severity (on the numerical rating scale) and/or headache frequency (determined by monthly headache days [MHD]) compared to baseline. Headache freedom was defined as <1 MHD.

Relevant covariates were defined as follows: severity of papilloedema on the Frisén scale from 0 (no papilloedema) to 5 (severe papilloedema) at diagnosis; resolution of papilloedema defined as Frisén scale 0 6 months after baseline; amount of weight loss achieved 6 months from baseline as a percentage loss; use of invasive therapy (ventriculo‐peritoneal shunt or optic nerve sheath fenestration) [10].

Data curation and data analysis

The data relevant to this study were extracted from the VIIH database. The data contained in the VIIH database had already been regularly examined for outliers by two independent auditors (GB and PP). In addition, a random sample of 10% of the recorded patients was analysed to confirm the quality of the original data collection. In order to further mitigate possible biases in the analysis of retrospective clinical data, a thorough quality control of the extracted data was carried out again for this study, in which the data were examined for outliers and a random sample of 5% of the recorded patients was re‐evaluated entirely.

Statistical analyses were performed using R Statistical Software (version 4.0.0). Univariate group comparisons were performed using the chi‐squared test, Fisher exact test, Mann–Whitney U test or independent t test (with Welch correction for unequal standard deviations between the groups) as appropriate. Univariate correlation analyses were calculated using Pearson or Spearman‐rho tests, depending on the presence of a normal distribution. To investigate clinical outcome, the proportions of outcome parameters reached were initially compared univariately between IC and SC. Subsequently, multivariate analyses were performed using binary‐logistic bias‐reduced logistic regression models according to Firth (a method based on penalized likelihood, which increases the efficiency of the estimators in logistic regression models with small samples; R package ‘logistf’, version 1.24.1) with outcome parameters as the dependent variable and group affiliation as the independent variable (IC vs. SC) [14]. The corrected Akaike information criterion was used to select the best‐fitting model from a predefined set of known relevant covariates (for visual outcomes, age, BMI, cerebrospinal fluid [CSF] opening pressure, visual impairment at diagnosis, percentage weight loss, resolution of papilloedema, use of invasive therapy; for headache outcomes, age, BMI, CSF opening pressure, MHD/headache severity at baseline, extent of papilloedema, weight loss, resolution of papilloedema and use of invasive therapy) and all other variables displaying an association with the respective outcome parameter p < 0.2 in univariate analyses [15]. Predefined subgroup analyses were conducted for patients with a language barrier (defined as German language proficiency ≤B1) and patients with a first‐generation migration background in order to explicitly examine the effects of IC on these potentially underserved patient groups. To check for the only systematic difference between IC and SC in standardized operating procedures for treatment, sensitivity analyses were conducted by removing patients who received GLP‐1‐RA.

The robustness of all regression models to unidentified confounding factors (bias) was quantified using the Rosenbaum sensitivity test according to the Hodges–Lehmann gamma [16]. Missing values were treated by multiple (20‐fold) imputation using the MNAR (missing not at random) approach with pooling of estimates according to Rubin's rules [17]. Significance level was set at a two‐sided p value <0.05.

RESULTS

Of 91 and 90 patients diagnosed with IIH during the respective study periods, 85 patients in the IC group and 81 in the SC group were included. Characteristics of both groups are shown in Table 1. There were no statistically significant differences between the groups at baseline, neither in terms of clinical nor demographic aspects.

TABLE 1 Characteristics in integrated and standard care.

	Integrated care (n = 85)	Standard care (n = 81)	p value	
Female a	77 (90.6)	73 (90.1)	0.999 d	
Age at diagnosis (years) b	33.6 (9.8)	32.8 (10.3)	0.250 e	
Time from referral to diagnosis c (days)	15 (1–62)	19 (1–82)	0.319 f	
Education level a	0.993 d	
≤9 years	34 (40.0)	33 (40.7)	
High school degree	29 (34.1)	27 (33.3)	
University degree	22 (25.9)	21 (25.9)	
Place of residence a	0.851 d	
Vienna	64 (75.3)	62 (76.5)	
Outside Vienna	21 (24.7)	19 (23.5)	
BMI (kg/m2) c	31.8 (18.2–60.5)	33.0 (17.3–65.6)	0.523 f	
CSF opening pressure (cmH2O) c	33 (26–59)	31 (26–63)	0.422 d	
Papilloedema grade (Frisén scale) c	3 (0–5)	3 (0–5)	0.872 f	
Visual impairment a	61 (71.8)	56 (69.1)	0.736 d	
Headache severity (NRS) c	5.5 (0–10)	6.0 (0–10)	0.572 f	
Headache frequency (MHD) c	18 (0–30)	17 (0–30)	0.644 f	
Chronic headache c	47 (55.3)	46 (56.8)	0.877 d	
First generation migration background a	49 (57.7)	48 (59.3)	0.833 d	
Language barrier (level ≤B1)	27 (31.8)	28 (34.6)	0.701 d	
Time from diagnosis to treatment initiation c (days)	1 (0–17)	2 (0–29)	0.451 f	
Acetazolamide during observation period a	83 (97.7)	80 (98.8)	0.999 d	
Maximum dosage (mg) c	750 (250–2000)	750 (250–2000)	0.893 f	
Topiramate during observation period a	14 (16.5)	16 (19.8)	0.688 d	
Maximum dosage (mg) c	62.5 (25–200)	50 (25–200)	0.724 f	
AntiCGRPmAbs during observation period a	7 (8.2)	11 (13.6)	0.323 d	
Invasive treatment (ventriculoperitoneal shunt) a	8 (9.3)	7 (8.6)	0.999 d	
Abbreviations: antiCGRPmAbs, anti‐calcitonin gene related peptide monoclonal antibodies; BMI, body mass index; CSF, cerebrospinal fluid; MHD, monthly headache days; NRS, numerical rating scale.

a Absolute number (percentage).

b Mean (standard deviation).

c Median (range).

d Calculated with chi‐squared test.

e Calculated with t test for independent groups.

f Calculated with Mann–Whitney U test.

Visual outcome

At 6 months’ follow‐up, visual impairment seemed to be slightly less frequent in IC than in SC (50.6% vs. 58.0%; p = 0.354). In the subgroups with migration background and language barrier, visual impairment was found in 51.0% (25/49) and 51.9% (14/27) in IC compared to 60.4% (29/48) and 64.3% (18/28) in SC (p = 0.416 and p = 0.418). In the multivariate regression model, IC was not associated with a statistically significant reduction in the risk of visual impairment at follow‐up 6 months after baseline (odds ratio [OR] 0.87, p = 0.231; see Table 2 and Figure 2). Again, risk reduction appeared slightly larger in the subgroups with migration background (OR 0.81, p = 0.202) and language barrier (OR 0.79, p = 0.173). The presence of visual impairment at baseline was the only statistically significant predictor of visual impairment at follow‐up (OR 6.05, p < 0.001; Table 2 and Figure 2).

TABLE 2 Multivariate analysis of the impact of integrated care on clinical outcome in patients with IIH 6 months after diagnosis.

	Odds ratio a	95% CI	p value	
Visual impairment	
Integrated care (vs. reference of standard care)	0.87	0.69–1.16	0.231	
Visual impairment at baseline	6.05	2.30–15.9	<0.001	
Weight loss (per 5%)	0.74	0.51–1.12	0.103	
Invasive treatment	2.61	0.76–14.8	0.175	
Visual worseningb	
Integrated care (vs. reference of standard care)	0.67	0.41–1.25	0.354	
Visual impairment at baseline	2.02	1.19–3.86	0.039	
Weight loss (per 5%)	0.77	0.28–1.13	0.146	
Invasive treatment	7.21	1.54–33.7	0.028	
Headache improvement	
Integrated care (vs. reference of standard care)	2.24	1.52–4.33	<0.001	
Headache frequency at baseline (per 5 MHD)	0.82	0.61–0.94	0.013	
Remission of papilloedema	1.42	0.88–1.96	0.192	
Weight loss (per 5%)	1.97	1.31–2.75	<0.001	
Headache freedom	
Integrated care (vs. reference of standard care)	1.75	1.11–3.09	0.031	
Age (per 5 years)	0.82	0.69–1.14	0.212	
Headache frequency at baseline (per 5 MHD)	0.69	0.48–0.82	<0.001	
Weight loss (per 5%)	1.29	0.91–2.08	0.197	
Note: Corrected Akaike information criterion was used to select the best‐fitting model from known relevant covariates and other variables that were associated with the respective outcome measure with a p value <0.2 in univariate analyses.

Abbreviation: CI, confidence interval; IIH, idiopathic intracranial hypertension; MHD, monthly headache days.

a Calculated using binary‐logistic bias‐reduced logistic regression models according to Firth with clinical endpoints as the dependent variable and group affiliation as the independent variable (integrated interdisciplinary one‐stop shop vs. standard care). Values above/below 1 indicate a higher/lower probability of clinical endpoints occurring.

FIGURE 2 Impact of integrated care on clinical outcome in the overall cohort and in subgroups with migration background and language barrier. Calculated using binary‐logistic bias‐reduced logistic regression models according to Firth with clinical endpoints as the dependent variable and group affiliation as the independent variable (integrated specialized outpatient clinic vs. standard care). Values above 1 indicate outcome favouring care in the integrated interdisciplinary one‐stop shop compared to standard care.

Visual worsening occurred in 8.2% and 12.4% of patients in IC and SC, respectively (p = 0.448). In the subgroup with migration background, visual worsening tended to be less frequent in IC than in SC (8.2% [4/49] vs. 14.6% [7/48], p = 0.356). A similar trend was seen in the language barrier subgroup (11.1% [3/27] vs. 25.0% [7/26], p = 0.295). In multivariate analysis, IC was not associated with a significant reduction in the risk of visual worsening (OR 0.67, p = 0.354; see Table 2 and Figure 2). Similarly, there were only numerical trends favouring IC over SC (but no statistically significant differences) in the subgroup analyses for migration background (OR 0.54, p = 0.112) and language barrier (OR 0.44, p = 0.097; Figure 2). The presence of visual impairment at baseline (OR 2.02, p = 0.039) and invasive treatment (OR 7.21, p = 0.028) were associated with a higher risk of visual worsening (Table 2).

Headache outcome

Headache improvement was achieved significantly more often in IC than in SC (89.4% vs. 65.4%, p < 0.001), which was also true for the subgroups with migration background (89.8% [44/49] vs. 58.3% [28/48], p < 0.001) and language barrier (88.9% [24/27] vs. 50.0% [14/28], p = 0.003). In multivariate analysis, IC was significantly associated with a higher probability of headache improvement compared to SC (OR 2.24, p < 0.001; Table 2 and Figure 2). Lower headache frequency at baseline (OR 0.82 per 5 days/month, p = 0.013) and a higher degree of weight loss (OR 1.97 per 5% loss, p < 0.001) were independent predictors of headache improvement (Table 2). The effect of IC on headache improvement appeared even more pronounced in the subgroups of patients with migration background (OR 2.87, p < 0.001) and language barrier (OR 3.22, p < 0.001; Figure 2).

Similar to headache improvement, headache freedom was observed significantly more frequently in IC than in SC (36.8% vs. 21.0%, p = 0.031). Again, this effect remained significant in the subgroup with migration background (36.7% [18/49] vs. 16.7% [8/48], p = 0.038) and language barrier (40.7% [11/27] vs. 14.3% [4/28], p = 0.037). In the multivariate model, IC showed a significantly higher probability of achieving headache freedom with reference to SC (OR 1.75, p = 0.031; see Table 2 and Figure 2). Lower headache frequency at baseline was the only other independent significant predictor of headache freedom (OR 0.69 per 5 days/month, p < 0.001). Similar to the findings for headache improvement, the superiority of IC over SC seemed to be larger in the subgroups with migration background (OR 2.27, p < 0.001) and language barrier (OR 3.07, p < 0.001; Figure 2). Sensitivity analyses removing patients who received GLP‐1‐RA (n = 24) did not indicate a relevant impact on visual or headache outcome.

DISCUSSION

Aiming to describe the effects of one‐stop specialized interdisciplinary IC for IIH, it was found that the clinical outcome in terms of headache improvement and headache freedom was significantly improved by IC, with an almost doubling of the probabilities of achieving headache improvement (OR 2.24) and headache freedom (OR 1.74) independent of other influencing factors. Importantly, these effects not only remained significant but appeared more pronounced in subgroups of patients with migration background and language barrier. There were no statistically significant differences in visual outcomes between the interdisciplinary integrated one‐stop shop and SC, although trends towards better outcome with IC were observed.

In the literature, there is only one comprehensive description of an interdisciplinary or multidisciplinary organizational structure for IIH patients, which is established at the Danish Headache Centre in Copenhagen [6]. There are several descriptions of multidisciplinary treatment protocols for IIH, which unanimously advocate the involvement of various specialist disciplines rather than care provided by a single discipline [9, 18, 19, 20, 21, 22, 23]. Some protocols are limited to neurology, (neuro) ophthalmology and neurosurgery to identify patients whose visual function is acutely at risk [9, 21, 22]. Others recommend the additional involvement of secondary disciplines or healthcare professions to address other relevant aspects of IIH, for example nutritional counselling and physiotherapy to support weight loss or concomitant psychological and/or psychiatric care to treat patients' comorbidities such as depression or eating disorders [6, 8, 19, 23, 24]. A one‐stop structure for IIH, such as the Vienna Interdisciplinary Integrated Specialized Outpatient Clinic for IIH, has not yet been described in the field of IIH. Although interdisciplinary/multidisciplinary management of IIH is generally recommended, there are no data on the explicit effects of interdisciplinary/multidisciplinary structures of IIH care on clinical outcome.

Visual outcome

Objectively measurable clinical outcome in IIH is typically determined by the highest associated health risk, the risk (or progression) of visual impairment. Rates of visual worsening in observational studies range from 10% to 28% [10, 18, 25, 26, 27, 28, 29, 30, 31]. Although there are no head‐to‐head studies, indirect comparisons suggest that visual outcome in observational studies is slightly better in centres offering multidisciplinary/interdisciplinary care [10, 18, 25, 26, 27, 28, 29, 30, 31]. At a Spanish tertiary hospital, the implementation of a multidisciplinary follow‐up protocol significantly reduced the rate of necessary invasive therapies, suggesting an indirect improvement in visual outcome [18]. However, such indirect comparisons should be viewed with great caution due to a variety of potential biases including selection bias and inherent differences in healthcare systems, such as preferred treatment methods or access to specialized care. Of note, visual outcome has improved over the last 20 years regardless of the type of care organization, which may introduce a time bias into this indirect comparison [32]. In our study, the rate of visual worsening in SC (12.4%) was in line with observational studies from centres offering multidisciplinary/interdisciplinary care. The rate of 8.2% in IC conveys a 33% risk reduction of visual deterioration in the multivariate analysis. Whilst the threshold of statistical significance was not reached, this is probably due to the low event rate in a relatively short follow‐up and the number of cases available, that is, insufficient power.

Headache outcome

Whilst visual impairment is often the primary concern in IIH, long‐term outcome is also determined by the disabling and often chronic headache [4]. However, data on headache outcome in IIH are significantly less extensive than those on visual outcome. In the available studies, a significant improvement (i.e., ≥50%) in headache is reported in 23%–67% of patients with slightly better results in centres using multidisciplinary/interdisciplinary care [10, 25, 27, 28, 32, 33, 34, 35, 36]. In the present study, the rate of significant headache improvement (65%) in SC is in line with the upper echelon of centres offering multidisciplinary/interdisciplinary care. IC was associated with a statistically significant and clinically relevant increase of the headache improvement rate (89%), doubling the probability of achieving headache improvement and headache freedom independent of other factors. It is hypothesized that this improvement is primarily due to earlier and improved access to standardized and systematic headache treatment provided by specialized neurologists within the one‐stop‐shop concept. Importantly, our data clearly show that socioeconomically underprivileged groups such as patients with migration background and/or language barrier benefitted even more from the one‐stop shop. Underlying reasons may include the comprehensive availability of interpreters in IC and the equally comprehensive use of multilingual headache calendars, which may significantly facilitate the anamnesis, which is essential for tailoring headache treatment, and thus improve treatment success. Another possible explanation may be the facilitated access to specialized care in one‐stop outpatient clinics, which is otherwise difficult due to the scarcity of services, particularly for underprivileged patient groups, a phenomenon well known in other chronic diseases with complex management [37, 38].

Limitations

The retrospective design of the study entails a number of limitations. The lack of randomization may induce several biases, for example a selection bias in the sense of an unbalanced selection of patients in a treatment group. However, this is mitigated by the VIIH database, which includes most IIH patients from our geographical area, and the very unselective inclusion criteria [10, 39]. Comparing patients from different time periods could theoretically lead to a systematic bias of the mean shift (Will Rogers phenomenon), for example due to changes in the diagnostic and treatment processes or an immortality‐of‐time bias [39, 40]. This is particularly relevant because the SARS‐CoV‐2 pandemic and the measures to combat the pandemic lie between the investigated period of SC and that of the intervention group. However, the comparison period for SC was chosen to minimize the direct and indirect influences of the SARS‐CoV‐2 pandemic and the measures to combat the pandemic. It is possible that patient behaviour regarding use of medical services may have changed as a result. Still, Rosenbaum sensitivity tests with Hodges–Lehmann gamma indicated robustness to bias by unidentified confounders [16]. Due to limited sample size owing to the rarity of IIH, correction for multiple comparisons was not applied, increasing the likelihood of a type I error. However, this is mitigated by a priori defined research questions and by the use of the corrected Akaike information criterion in the multivariable models. Finally, there are other areas of healthcare that are probably relevant for managing patients with IIH which are currently not included in our interdisciplinary IIH concept, such as psychiatry consultations targeting the high prevalence of psychiatric comorbidities in IIH [41, 42]. This is an important future direction that it is aimed to achieve.

In conclusion, the present study conducted in a representative and large (considering the rarity of IIH) sample of patients with IIH shows that one‐stop interdisciplinary IC independently improves headache outcome and potentially also visual outcome, particularly in socioeconomically disadvantaged patient groups with migration background and/or language barrier.

For clinical routine, this supports international consensus recommendations that IIH should be managed at specialized centres with access to the necessary resources including an interdisciplinary team [8, 9]. Providing structured central coordination to facilitate and improve access to interdisciplinary management is clearly an important direction to further improve outcome. This is deemed especially relevant as over 90% of patients with IIH currently do not have access to interdisciplinary/multidisciplinary care [43]. Our data can be leveraged in the interaction with stakeholders and decision‐makers to ensure that IIH patients are provided with the best possible care in the most efficient way.

AUTHOR CONTRIBUTIONS

Gabriel Bsteh: Conceptualization; investigation; writing – original draft; methodology; formal analysis; data curation; supervision. Stefan Macher: Investigation; writing – review and editing; methodology. Nik Krajnc: Investigation; methodology; validation; writing – review and editing; data curation. Wolfgang Marik: Investigation; methodology; writing – review and editing. Martin Michl: Investigation; methodology; writing – review and editing. Nina Müller: Investigation; methodology; writing – review and editing. Sina Zaic: Investigation; methodology; writing – review and editing. Jürgen Harreiter: Investigation; methodology; writing – review and editing. Klaus Novak: Investigation; methodology; writing – review and editing. Christian Wöber: Investigation; methodology; writing – review and editing. Berthold Pemp: Investigation; methodology; writing – review and editing; supervision.

FUNDING INFORMATION

There was no funding to this research.

CONFLICT OF INTEREST STATEMENT

Gabriel Bsteh: has participated in meetings sponsored by, received speaker honoraria or travel funding from Biogen, Celgene/BMS, Lilly, Merck, Novartis, Roche, Sanofi‐Genzyme and Teva, and received honoraria for consulting Biogen, Celgene/BMS, Merck, Novartis, Roche, Sanofi‐Genzyme and Teva. He has received unrestricted research grants from Celgene/BMS and Novartis. Stefan Macher: declares no conflict of interest relevant to this study. Nik Krajnc: has participated in meetings sponsored by, received speaker honoraria or travel funding from Alexion, BMS/Celgene, Janssen‐Cilag, Merck, Novartis, Roche and Sanofi‐Genzyme and held a grant for a Multiple Sclerosis Clinical Training Fellowship Programme from the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS). Wolfgang Marik: declares no conflict of interest relevant to this study. Martin Michl: declares no conflict of interest relevant to this study. Nina Müller: declares no conflict of interest relevant to this study. Sina Zaic: declares no conflict of interest relevant to this study. Jürgen Harreiter: declares no conflict of interest relevant to this study. Klaus Novak: declares no conflict of interest relevant to this study. Christian Wöber: has received honoraria for consultancy/speaking from Apomedica, Curelator, Eli Lilly, Grünenthal, Hermes, Lundbeck, Novartis, Pfizer, Ratiopharm/Teva and Stada. Berthold Pemp: has received honoraria for consultancy/speaking from Chiesi, GenSight, Novartis and Santen.

PATIENT CONSENT STATEMENT

The study was approved by the ethics committee of the Medical University of Vienna (ethics approval number 2216/2022). As this is a retrospective study, the ethics committee did not require a written declaration of consent from the study participants.

ACKNOWLEDGEMENTS

All the VIIH investigators, clinical research staff and especially the patients are thanked for helping to collect these data. The named individuals were not compensated for their help. VIIH investigators in alphabetical order: Bsteh, Gabriel (Department of Neurology, Medical University of Vienna); Grechenig, Christoph (Department of Ophthalmology, Medical University of Vienna); Kirchner, Karl (Department of Ophthalmology, Medical University of Vienna); Krajnc, Nik (Department of Neurology, Medical University of Vienna); Macher, Stefan (Department of Neurology, Medical University of Vienna); Michl, Martin (Department of Ophthalmology, Medical University of Vienna); Mitsch, Christoph (Department of Ophthalmology, Medical University of Vienna); Müller, Nina (Department of Neurology, Medical University of Vienna); Pemp, Berthold (Department of Ophthalmology, Medical University of Vienna); Reitner, Andreas (Department of Ophthalmology, Medical University of Vienna); Wöber, Christian (Department of Neurology, Medical University of Vienna); Zebenholzer, Karin (Department of Neurology, Medical University of Vienna).

DATA AVAILABILITY STATEMENT

Data supporting the findings of this study are available from the corresponding author upon reasonable request by a qualified researcher and upon approval by the ethics committee and the data‐clearing committee of the Medical University Vienna.
==== Refs
REFERENCES

1 Markey KA , Mollan SP , Jensen RH , Sinclair AJ . Understanding idiopathic intracranial hypertension: mechanisms, management, and future directions. Lancet Neurol. 2016;15 :78‐91.26700907
2 Goudie C , Shah P , McKee J , Foot B , Kousha O , Blaikie A . The incidence of idiopathic intracranial hypertension in Scotland: a SOSU study. Eye. 2019;33 :1570‐1576.31040381
3 Kilgore KP , Lee MS , Leavitt JA , et al. Re‐evaluating the incidence of idiopathic intracranial hypertension in an era of increasing obesity. Ophthalmology. 2017;124 :697‐700.28187976
4 Simone RD , Sansone M , Bonavita V . Headache in idiopathic intracranial hypertension. A CGRP‐dependent head pain? Neurol Sci. 2020;41 :417‐421.
5 Hoffmann J , Mollan SP , Paemeleire K , Lampl C , Jensen RH , Sinclair AJ . European Headache Federation guideline on idiopathic intracranial hypertension. J Headache Pain. 2018;19 :93.30298346
6 Jensen RH , Vukovic‐Cvetkovic V , Korsbaek JJ , Wegener M , Hamann S , Beier D . Awareness, diagnosis and management of idiopathic intracranial hypertension. Lifestyles. 2021;11 :718.
7 Mollan SP , Davies B , Silver NC , et al. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurology Neurosurg Psychiatr. 2018;89 :1088‐1100.
8 Thurtell MJ , Kawasaki A . Update in the management of idiopathic intracranial hypertension. Neurol Clin. 2021;39 :147‐161.33223080
9 Brady T , Vegunta S , Crum AV , et al. Interdisciplinary protocol for the management of vision‐threatening papilledema. J Neuroophthalmol. 2022;42 :495‐501.35439211
10 Pruckner P , Mitsch C , Macher S , et al. The Vienna idiopathic intracranial hypertension database—an Austrian registry. Wien Klin Wochenschr. 2024;136 :32‐39.37650963
11 Friedman DI , Liu GT , Digre KB . Revised diagnostic criteria for the pseudotumor cerebri syndrome in adults and children. Neurology. 2013;81 :1159‐1165.23966248
12 Wüllner U , Fink B , Dodegge M , et al. Idiopathische intrakranielle Hypertension (IIH), S1‐Leitlinie für Diagnostik und Therapie in der Neurologie. Leitlinien für Diagnostik und Therapie in der Neurologie. www.dgn.org/leitlinien. 2019.
13 Rosser DA , Cousens SN , Murdoch IE , Fitzke FW , Laidlaw DAH . How sensitive to clinical change are ETDRS logMAR visual acuity measurements? Invest Ophthalmol Vis Sci. 2003;44 :3278‐3281.12882770
14 Heinze G , Schemper M . A solution to the problem of separation in logistic regression. Stat Med. 2002;21 :2409‐2419.12210625
15 Claeskens G . Statistical model choice. Annu Rev Stat Appl. 2016;3 :233‐256.
16 Rosenbaum PR , Rubin DB . Reducing bias in observational studies using subclassification on the propensity score. J Am Stat Assoc. 1984;79 :516‐524.
17 Council National Research . The Prevention and Treatment of Missing Data in Clinical Trials. National Academies Press (US); 2010. doi:10.17226/12955
18 González‐Hernández A , Tandón‐Cárdenes L , Cabrera‐Naranjo F , et al. Description of the follow‐up protocol for idiopathic intracranial hypertension in the neuro‐ophthalmological unit of a tertiary hospital. Rev Neurol. 2013;56 :505‐509.23658032
19 Mollan SP , Markey KA , Benzimra JD , et al. A practical approach to, diagnosis, assessment and management of idiopathic intracranial hypertension. Pract Neurol. 2014;14 :380‐390.24809339
20 McCluskey G , Mulholland DA , McCarron P , McCarron MO . Idiopathic intracranial hypertension in the northwest of Northern Ireland: epidemiology and clinical management. Neuroepidemiology. 2015;45 :34‐39.26201454
21 Chagot C , Blonski M , Machu J‐L , Bracard S , Lacour JC , Richard S . Idiopathic intracranial hypertension: prognostic factors and multidisciplinary management. J Obes. 2017;2017 :5348928.28884026
22 Toscano S , Fermo SL , Reggio E , et al. An update on idiopathic intracranial hypertension in adults: a look at pathophysiology, diagnostic approach and management. J Neurol. 2020;268 :1‐20.32651671
23 Alves S , Sousa N , Cardoso L , Alves J . Multidisciplinary management of idiopathic intracranial hypertension in pregnancy: case series and narrative review. Braz J Anesthesiol. 2022;72 :790‐794.33757747
24 Puustinen T , Tervonen J , Avellan C , et al. Psychiatric disorders are a common prognostic marker for worse outcome in patients with idiopathic intracranial hypertension. Clin Neurol Neurosurg. 2019;186 :105527.31586855
25 Yri HM , Wegener M , Sander B , Jensen R . Idiopathic intracranial hypertension is not benign: a long‐term outcome study. J Neurol. 2012;259 :886‐894.22008872
26 Best J , Silvestri G , Burton B , Foot B , Acheson J . The incidence of blindness due to idiopathic intracranial hypertension in the UK. Open Ophthalmol J. 2013;7 :26‐29.23898356
27 Lai LT , Danesh‐Meyer HV , Kaye AH . Visual outcomes and headache following interventions for idiopathic intracranial hypertension. J Clin Neurosci. 2014;21 :1670‐1678.24974193
28 Piper RJ , Kalyvas AV , Young AM , et al. Interventions for idiopathic intracranial hypertension. Cochrane Database Syst Rev. 2015;8 :CD003434.
29 Wall M , Falardeau J , Fletcher WA , et al. Risk factors for poor visual outcome in patients with idiopathic intracranial hypertension. Neurology. 2015;85 :799‐805.26245929
30 Hatem CF , Yri HM , Sørensen AL , Wegener M , Jensen RH , Hamann S . Long‐term visual outcome in a Danish population of patients with idiopathic intracranial hypertension. Acta Ophthalmol. 2018;96 :719‐723.29405582
31 Behbehani R , Ali A , Al‐Moosa A . Course and predictors of visual outcome of idiopathic intracranial hypertension. Neuro‐Ophthalmology. 2022;46 :80‐84.35273409
32 Mollan SP , Chong YJ , Grech O , Sinclair AJ , Wakerley BR . Current perspectives on idiopathic intracranial hypertension without papilloedema. Lifestyles. 2021;11 :472.
33 Yri HM , Rönnbäck C , Wegener M , Hamann S , Jensen RH . The course of headache in idiopathic intracranial hypertension: a 12‐month prospective follow‐up study. Eur J Neurol. 2014;21 :1458‐1464.25070715
34 Grech O , Mollan SP , Wakerley BR , Alimajstorovic Z , Lavery GG , Sinclair AJ . Emerging themes in idiopathic intracranial hypertension. J Neurol. 2020;267 :3776‐3784.32700012
35 Mollan SP , Grech O , Sinclair AJ . Headache attributed to idiopathic intracranial hypertension and persistent post‐idiopathic intracranial hypertension headache: a narrative review. Headache. 2021;61 :808‐816.34106464
36 Mollan SP , Wakerley BR , Alimajstorovic Z , et al. Intracranial pressure directly predicts headache morbidity in idiopathic intracranial hypertension. J Headache Pain. 2021;22 :118.34620087
37 Foo CD , Surendran S , Tam CH , et al. Perceived facilitators and barriers to chronic disease management in primary care networks of Singapore: a qualitative study. BMJ Open. 2021;11 :e046010.
38 Settipani CA , Hawke LD , Cleverley K , et al. Key attributes of integrated community‐based youth service hubs for mental health: a scoping review. Int J Ment Health Syst. 2019;13 :52.31367230
39 Kalincik T , Butzkueven H . Observational data: understanding the real MS world. Mult Scler J. 2016;22 :1642‐1648.
40 Sormani MP , Tintore M , Rovaris M , et al. Will Rogers phenomenon in multiple sclerosis. Ann Neurol. 2008;64 :428‐433.18688811
41 Korsbæk JJ , Beier D , Hagen SM , Molander LD , Jensen RH . Psychiatric comorbidities in patients with idiopathic intracranial hypertension: a prospective cohort study. Neurology. 2022;99 :e199‐e208. doi:10.1212/WNL.0000000000200548 35473759
42 Wallentin T , Linnet J , Lichtenstein MB , et al. The impact of eating disorders on idiopathic intracranial hypertension. Cephalalgia. 2024;44 :03331024241237237.
43 Bayır BRH , Yavuz ENV , Baykan B . Idiopathic intracranial hypertension: do we diagnose and manage it appropriately in the light of current data? Clin Neurol Neurosurg. 2021;208 :106879.34418707
