Is obstructive sleep apnea associated with erythrocytosis? A systematic review and meta-analysis.
Level 3 - non-randomized controlled study
Systematic review and meta-analysis of observational studies
PubMed 35434329 · doi:10.1002/lio2.751
What was done
A systematic review and meta-analysis searching PubMed, Web of Science, and Cochrane Library through September 1, 2021, for studies comparing hematocrit values between patients with obstructive sleep apnea (OSA) and controls. Pooled standardized mean differences (SMD) with 95% confidence intervals were calculated, and subgroup analyses were performed by disease severity, sex, and publication year.
What was found
Across 11 studies with 4,608 patients with OSA, hematocrit was significantly higher in OSA patients versus controls (SMD 0.19; 95% CI, 0.08–0.29; p < .01). Stratified by severity, hematocrit was significantly higher only in severe OSA (SMD 0.34; 95% CI, 0.08–0.59; p < .01), with no significant differences in mild or moderate OSA. Elevations remained significant in studies including only female patients (SMD 0.25; 95% CI, 0.12–0.38; p < .01) and in studies published after 2012 (SMD 0.17; 95% CI, 0.06–0.28; p < .01).
Why it matters
This review shows that while OSA leads to a slight elevation in hematocrit, particularly in severe cases, the increase is modest and unlikely by itself to cause clinically meaningful erythrocytosis.
Limits
The total number of control participants is not reported in the abstract. The abstract does not specify whether primary studies controlled for important confounders such as smoking status, obesity hypoventilation syndrome, altitude, or daytime hypoxemia, nor does it provide absolute hematocrit values.
Cited by
- contradicts Elevated hematocrit and hemoglobin in physically unfit, non-exercising individuals is a common clinical indicator of sleep apnea.