Association of Elevated Levels of Vascular Endothelial Growth Factor in Obstructive Sleep Apnea Syndrome with Patient Age rather than with Obstructive Sleep Apnea Syndrome Severity

Abstract

Background: Although certain studies report high levels of vascular endothelial growth factor (VEGF) in obstructive sleep apnea syndrome (OSAS), the effect of systemic hypoxia on circulating VEGF remains controversial. Objectives: To study the association of serum VEGF and OSAS in a large group of patients. Methods: One hundred patients with OSAS (mean age 58.1 ± 12.4 years, mean body mass index 30.6 ± 5.4 kg/m²) were tested for serum VEGF levels, and the findings were correlated with the severity of OSAS, as determined by the apnea-hypopnea index (AHI) on the basis of polysomnography and background data. Results: The mean AHI was 40.0 ± 21.2 (range 10–106). Mean minimal oxygen saturation was 80.6 ± 11.7% (range 43–98%) and mean time of oxygen saturation under 90% was 50.0 ± 75.0 min (range 0–300 min). The mean VEGF level was 445.2 ± 289.8 pg/ml in the study group (vs. 280 pg/ml reported in normal controls). The mean platelet count was 233.8 ± 64.4 10³/ml and the mean VEGF/platelet ratio was 1.95 ± 1.40 pg/10⁶. There was no association of VEGF or VEGF/platelets with the severity of OSAS. However, both factors showed a significant correlation with patient age (r = 0.224, p = 0.01 and r = 0.425, p = 0.01, respectively). Age was the only parameter to significantly predict VEGF and VEGF/platelets on multivariate analysis (R² = 0.713, p = 0.001 and R² = 0.844, p = 0.001, respectively). Conclusion: The elevation of serum VEGF in OSAS is not associated with the severity of the disease, but it is associated with patient age. VEGF might be involved in the long-term adaptive mechanism in OSAS, and its age-dependent increase might partly explain the reduced mortality in elderly OSAS patients.

Skeletal Muscle Morphology and Aerobic Capacity in Patients with Obstructive Sleep Apnoea Syndrome

“…The occurrence of hypoxia is strengthened by the high levels of plasma VEGF reported in patients with OSAS [41,42,43]. Thus, intermittent local hypoxia during sleep might cause an increase in VEGF levels as shown in other studies [41,42,43] and an increase in microvessel network as shown in our study.…”

“…In this respect, OSAS is characterized by arterial oxygen desaturation during sleep with severe nighttime hypoxia (60–80% oxygen saturation), presumably causing local tissue hypoxia [39, 40]. The occurrence of hypoxia is strengthened by the high levels of plasma VEGF reported in patients with OSAS [41,42,43]. Thus, intermittent local hypoxia during sleep might cause an increase in VEGF levels as shown in other studies [41,42,43] and an increase in microvessel network as shown in our study.…”

Endothelial Function and Circulating Endothelial Progenitor Cells in Patients with Sleep Apnea Syndrome

“…Patients with sleep apnea have increased plasma levels of VEGF [15,16,17,18,19]. Recent findings suggest that vascular function is impaired in OSA and that endothelial dysfunction may precede and predispose these patients to cardiovascular events [20,21,22,23,24].…”

Vascular Endothelial Growth Factor and Sleep Apnea: Clutching at Straws in the Night

“…Many but not all studies have found elevated VEGF levels in subjects with OSAS [6] . Some but not all investigations have observed a correlation between the severity of OSAS (as measured by the apnea/hypopnea index) and VEGF [6] .…”

“…Many but not all studies have found elevated VEGF levels in subjects with OSAS [6] . Some but not all investigations have observed a correlation between the severity of OSAS (as measured by the apnea/hypopnea index) and VEGF [6] . The relationship between OSAS and VEGF may be obscured by a possible correlation between VEGF and age, but reports vary as to whether this relationship exists [6] .…”