An observational study in Vitamin D Deficiency and Obstructive Sleep Apnea, sponsored by Hisar Intercontinental Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-08-26.
Sponsored by Hisar Intercontinental Hospital · Observational
This retrospective observational study evaluates the relationship between vitamin D status and obstructive sleep apnea (OSA) in adults. The study includes 269 participants divided into four groups: healthy controls, participants with simple snoring without OSA, patients with OSA without comorbidities, and patients with OSA with comorbidities.
The main objective is to compare serum 25-hydroxyvitamin D [25(OH)D] levels among these groups and to examine whether vitamin D status is associated with the presence and severity of OSA. Demographic characteristics, body mass index, laboratory measurements, and available overnight polysomnography findings are evaluated using existing medical records. The study also examines the distribution of vitamin D deficiency across the study groups and the relationship between vitamin D categories and OSA severity.
This retrospective comparative study evaluates serum 25-hydroxyvitamin D [25(OH)D] status across clinically distinct obstructive sleep apnea (OSA) phenotypes. Participants were classified into four groups: healthy controls, symptomatic participants with simple snoring/non-OSA (apnea-hypopnea index [AHI] \<5 events/hour), patients with OSA without comorbidities, and patients with OSA with comorbidities. OSA was defined as AHI ≥5 events/hour and categorized as mild, moderate, or severe according to conventional AHI thresholds.
Among patients with OSA, comorbid OSA was defined by the presence of at least one documented chronic condition, including hypertension, diabetes mellitus, cardiovascular disease, dyslipidemia, or hypothyroidism. Demographic and anthropometric characteristics, serum 25(OH)D concentrations, available routine laboratory measurements, and polysomnographic parameters were retrospectively obtained from existing medical records and hospital databases.
The study compares vitamin D status across the four groups and evaluates whether serum 25(OH)D concentrations and vitamin D categories are associated with OSA severity. The study also explores whether differences in vitamin D status across OSA phenotypes persist after accounting for age, sex, and body mass index.
801 studies on the registry are indexed under Vitamin D Deficiency; 60 are open to participants now.
This study's enrollment of 269 is above the median of 138 across 185 observational studies indexed under Vitamin D Deficiency.
Browse Vitamin D Deficiency studies →Hisar Intercontinental Hospital is the lead sponsor of 19 studies on the registry; none are open to participants now.
Counted across the registry records on this site, refreshed daily.
The study population consisted of adults evaluated at Hisar Intercontinental Hospital between 2024 and 2026. Participants included a healthy control group and adults who underwent overnight polysomnography because of symptoms suggestive of sleep-disordered breathing. PSG-evaluated participants were classified as simple snoring/non-OSA (AHI \<5 events/hour), OSA without comorbidities, or OSA with comorbidities. The final study population included 269 participants: 81 healthy controls, 49 non-OSA participants, 50 patients with non-comorbid OSA, and 89 patients with comorbid OSA.
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.
Adults aged 18 years or older. Participants with available serum 25-hydroxyvitamin D [25(OH)D] measurements. For PSG-evaluated groups, availability of overnight polysomnography data allowing classification according to the apnea-hypopnea index (AHI).
Participants meeting the predefined criteria for one of the study groups: healthy control, simple snoring/non-OSA, OSA without comorbidities, or OSA with comorbidities.
Exclusion Criteria:
Missing or insufficient data required for study-group classification. Missing serum 25(OH)D measurements. Incomplete polysomnographic data preventing determination of OSA status or severity in PSG-evaluated participants.
Individuals without documented obstructive sleep apnea or the predefined comorbid conditions, included as the healthy reference group. No study-specific intervention was assigned.
Symptomatic participants who underwent polysomnography and had an apnea-hypopnea index (AHI) \<5 events/h. No study-specific intervention was assigned.
Participants with OSA (AHI ≥5 events/h) without documented hypertension, diabetes mellitus, cardiovascular disease, dyslipidemia, or hypothyroidism. No study-specific intervention was assigned.
Participants with OSA (AHI ≥5 events/h) and at least one documented comorbid condition, including hypertension, diabetes mellitus, cardiovascular disease, dyslipidemia, or hypothyroidism. No study-specific intervention was assigned.
Serum 25-Hydroxyvitamin D Levels Across Study Groups
Serum 25-hydroxyvitamin D \[25(OH)D\] concentrations were compared among healthy controls, simple snoring/non-OSA participants, patients with OSA without comorbidities, and patients with OSA with comorbidities.
Time frame: During the retrospective study period (2024-2026)
Distribution of Vitamin D Status Across Study Groups
Participants were categorized according to serum 25-hydroxyvitamin D \[25(OH)D\] concentrations as \<20 ng/mL, 20-30 ng/mL, or \>30 ng/mL. The distribution of these vitamin D categories was compared among healthy controls, simple snoring/non-OSA participants, patients with OSA without comorbidities, and patients with OSA with comorbidities.
Time frame: During the retrospective study period (2024-2026)
Association of Vitamin D Status With Polysomnographic Severity of OSA
The association of serum 25-hydroxyvitamin D \[25(OH)D\] status with polysomnographic severity of obstructive sleep apnea was evaluated using AHI and OSA severity categories (mild, moderate, and severe). Available polysomnographic parameters, including oxygen desaturation index (ODI) and minimum oxygen saturation (SpO₂), were also evaluated.
Time frame: During the retrospective study period (2024-2026)
Plan to share: No — Individual participant data will not be publicly shared because the study is based on retrospective clinical and laboratory records containing potentially sensitive patient information. De-identified data may be made available from the corresponding author upon reasonable request and subject to institutional and ethical approval.
No publications or documents are linked to this record.
This study is completed, as verified in Aug 2026. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Hisar Intercontinental Hospital