An observational study in Chiari Malformation Type I, sponsored by Karolinska Institutet. Enrolling by invitation at 1 site in Sweden. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-14.
Sponsored by Karolinska Institutet · Observational
The goal of this observational survey study is to investigate factors that may affect the health-related quality of life (HRQoL) in adults with Chiari malformation type 1 (CM1). The main questions it aims to answer are:
How do CM1 patients rate their HRQoL compared to the general population? Are there any factors that lead to better or worse HRQoL in CM1 patients? Is there a difference in HRQoL in operated versus non-operated CM1 patients?
Participants will be identified via the Swedish National Board of Health and Welfare's Patient register. They will be asked to participate in a survey of HRQoL containing standardized questionnaires, and their answers will be analyzed together with data from the Patient register. Their questionnaire answers will also be compared to normative Swedish data.
This is an observational, cross-sectional survey study investigating health-related quality of life (HRQoL) in adults with Chiari malformation type 1 (CM1).
A total of 1,004 adults with CM1 will be invited to participate, including 666 patients who have undergone surgery for CM1 and 338 patients who have not. Participants were identified through the Swedish National Board of Health and Welfare's National Patient Register, which holds data on all inpatient episodes as well as specialized outpatient visits in Sweden.
Operated patients were identified based on diagnosis of Arnold Chiari Malformation (ICD-code Q07.0) and posterior fossa decompression (procedure code ABE50) recorded in the National Patient Register between 2011 and 2024. Non-operated patients were identified based on a diagnosis of CM1 (ICD-10 code Q07.0) recorded during a visit to a neurosurgical outpatient clinic between 2021 and 2024. Patients with a diagnosis of spina bifida (ICD-10 code Q05.X) were excluded from the overall cohort. Non-operated patients with a record of duraplasty (procedure code AAK10) or another operation on the cranium or dura (procedure code AAK99) were excluded.
Participants will be contacted by mail and invited to complete an online survey administered through REDCap, hosted by Karolinska Institutet. The survey includes the Swedish version of the EQ-5D-3L, including the EQ Visual Analogue Scale (EQ-VAS), the Hospital Anxiety and Depression Scale (HADS), and a study-specific questionnaire focusing on clinical characteristics, medication use, sick leave, return to work, and attitudes toward surgical treatment.
Survey data will be linked to relevant information from the National Patient Register and the Swedish Social Insurance Agency. Register data will include information on diagnoses, surgical treatment, comorbidities, and relevant social insurance variables.
The primary outcomes are HRQoL measured using the EQ-5D-3L index score and EQ-VAS score. HRQoL will be compared with normative data collected from a general population in Stockholm, Sweden. HRQoL and associated factors will also be compared between operated and non-operated participants.
A priori power calculations indicated that, assuming a clinically relevant difference of 0.10 in EQ-5D index score, a standard deviation of 0.25, and a two-sided α of 0.05, responses from approximately 22% of the study population would be sufficient to achieve 80% power. Since the expected response rate is 30-50%, approximately 1,000 patients were chosen to ensure an adequate sample size.
Descriptive and inferential statistical methods will be used to evaluate differences between groups and identify factors associated with HRQoL. Continuous variables will generally be summarized using medians and interquartile ranges, and categorical variables using frequencies and proportions. Regression analyses will be used to identify possible predictors of better or worse HRQoL.
Participation is voluntary and requires informed consent. Personal data will be handled in accordance with applicable legislation and institutional procedures, with appropriate measures taken to protect participant confidentiality and data security.
34 studies on the registry are indexed under Arnold-Chiari Malformation; 10 are open to participants now.
This study's planned enrollment of 1,004 is above the median of 166 across 14 observational studies indexed under Arnold-Chiari Malformation.
Browse Arnold-Chiari Malformation studies →Karolinska Institutet is the lead sponsor of 1,148 studies on the registry; 276 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The study population consists of adult patients with Chiari malformation type 1 (CM1) identified through the Swedish National Patient Register, which contains nationwide information on inpatient and specialized outpatient care. To ensure diagnostic validity, non-operated patients were included only if they have a documented evaluation at a neurosurgical unit. Operated patients were identified through procedure codes recorded in the register.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Patients identified via the National Patient Register to have 1) diagnosis of Arnold Chiari Malformation (ICD-code Q07.0), 2) received posterior fossa decompression (procedure code ABE50), 3) no record of spina bifida diagnosis (Q05.X), which would indicate Chiari Malformation type 2. The group was limited to the years 2011-2024 to ensure approximately 2/3 of 1000 patients, resulting in 666 eligible participants. Only patients ≥18 years of age at the time the diagnosis was first recorded were included.
Patients identified via the National Patient Register to have 1) diagnosis of Arnold Chiari Malformation (ICD-code Q07.0), 2) the diagnosis recorded at a visit to a neurosurgical unit, 3) no record of posterior fossa decompression (procedure code ABE50) or the similar procedures duraplasty (procedure code AAK10) or another operation on the cranium or dura (procedure code AAK99), 4) no record of spina bifida diagnosis (Q05.X), which would indicate Chiari Malformation type 2. The group was limited to the years 2021-2024 to ensure approximately 1/3 of 1000 patients, resulting in 338 eligible participants. Only patients ≥18 years of age at the time the diagnosis was first recorded were included.
EQ-5D index score
Combined value of the five dimensions of the Euroqol five-dimensional three level (EQ-5D-3L) questionnaire, based on the United Kingdom value set. The index score has a value between 0 and 1, where 1 represents full health.
Time frame: Baseline
EQ-5D VAS score
The Euroqol five-dimensonial (EQ-5D) visual analog scale (VAS). The respondents rate their current health between 0 (worst imaginable health) and 100 (best imaginable health).
Time frame: Baseline
Hospital and Anxiety Depression Scale (HADS), total score
The participant responds to 14 items concerning psychological well-being, resulting in an anxiety score between 0-21 and a depression score 0-21, as well as a total score 0-42, where higher values indicate a more severe condition.
Time frame: Baseline
Employment status
Employment status defined as full time work, part time work, studies, sick leave, sick pension or retirement. For operated patients: employment status before surgery and after surgery For non-operated patients: current employment status
Time frame: Basline
Attitude towards surgery
As part of the study-specific questionnaire, participants in the operated group are asked if they would accept surgery if asked today.
Time frame: Baseline
Plan to share: Yes — Metadata describing the dataset will be made publicly available through the Karolinska Institutet (KI) Data Repository.
Supporting information: Informed consent form, Analytic code
Time frame: Will be available upon publication and as long as the KI Data Repository allows.
Access criteria: The underlying research data contain sensitive personal information and cannot be shared openly. Access may be granted to qualified researchers upon reasonable request and subject to ethical approval, data protection requirements, and institutional review. Access to supporting information, such as ICF and Analytic code, will be available upon request to the corresponding author.
No publications or documents are linked to this record.
Started Aug 2026 (actual). Primary completion is estimated for Nov 2026, 3 months after the start.
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