Vitamin D Deficiency Linked to Increased Obstructive Sleep Apnea Severity in Kids

Vitamin D deficiency was significantly associated with increased obstructive sleep apnea (OSA) severity among children, according to a cross-sectional study.

In a multivariable analysis of kids who were undergoing adenotonsillectomy, obstructive Apnea-Hypopnea Index (AHI) scores (which range from ≥5 to ≥30 apnea and hypopnea events per hour) were significantly lower in children with normal vitamin D levels compared with those with vitamin D deficiency (difference -14.6, 95% CI -27.2 to -2.2), reported Cristina Baldassari, MD, of the Children’s Hospital of the King’s Daughters and Eastern Virginia Medical School in Norfolk, and colleagues.

A 1.0-unit decrease in serum vitamin D levels was associated with an obstructive AHI increase of 0.7 (95% CI 0.04-1.40), they wrote in JAMA Otolaryngology–Head & Neck Surgery.

“If further substantiated, this association could provide additional insights not only into OSA pathophysiologic processes, but also into future treatment paradigms for children,” the authors wrote.

Baldassari told MedPage Today that “there are certain groups of kids that are more likely to have sleep apnea even after we do surgery, and so I’m always looking for different things that might kind of predict why they’re going to do worse, and if so, ways to fix it.”

Vitamin D deficiency is relatively easy to screen for and treat, she said. “It’s kind of a low-hanging fruit, for sure.”

In univariate analysis, vitamin D deficiency was associated with younger age (difference -5.0, 95% CI -7.2 to -2.8), Black race (OR 4.3, 95% CI 1.4-14.3), and female sex (OR 4.8, 95% CI 1.7-12.5), but these lost significance in the multivariable model.

A previous study showed that children with OSA had lower vitamin D levels compared with healthy controls, and an association between vitamin D levels and pediatric OSA was also seen in a study of white children with OSA and age- matched controls. The correlation between Black race and vitamin D deficiency has also been observed, and is thought to be related to decreased sunlight-stimulated vitamin D production of melanin-rich skin in northern latitudes.

However, the mechanisms behind the association between vitamin D levels and OSA severity are not well understood, Baldassari and colleagues noted. Low vitamin D levels have been linked to other conditions, including metabolic dysfunction, cardiovascular disease, asthma, and increased incidence of upper respiratory tract infections. Vitamin D deficiency may also play a role in immunomodulation and tissue growth, and it’s possible it has an anti-inflammatory role that affects adenotonsillar hypertrophy and chronic rhinitis. However, tonsil hypertrophy was not linked to vitamin D deficiency in this study.

“Perhaps low vitamin D levels could affect pharyngeal tone during sleep. Further research is needed to better understand how vitamin D levels affect OSA severity,” the authors wrote.

Baldassari said that “the thought was … if we can show vitamin D levels are lower, and they seem to impact outcomes … if we treat the vitamin D, will it make them less likely to have sleep apnea, even after surgery? And will they do better with surgery when we treat?” These are questions she said she plans to address in future studies.

For this study, Baldassari and team included 72 children ages 2 to 16 years with severe OSA (AHI ≥20 on polysomnogram) who were undergoing adenotonsillectomy at a tertiary care pediatric otolaryngology clinic from 2017 to 2022.

Those with neuromuscular disorders, craniofacial anomalies, history of OSA treatment with positive airway pressure, prior tonsil or adenoid surgery, and/or a history of vitamin D deficiency were excluded.

Mean patient age was 6.7 years, 52.8% were male, and 47.2% were white. The mean baseline AHI was 42.8, 49% had obesity, and 37.5% had vitamin D deficiency.

Upon enrollment, fasting blood samples were collected directly after anesthesia and analyzed for serum 25-hydroxyvitamin D levels, with levels less than 20 ng/mL considered deficient. These were assessed for correlation with polysomnography metrics.

The authors noted that they were limited by their use of a point-of-time estimation of vitamin D levels, as opposed to a duration of vitamin D deficiency, and post-surgery levels were unavailable. Vitamin D levels depend on geography because sunlight exposure varies by latitude, so this single-center study may not be generalizable to other locations, or to children with milder OSA.