Obstructive sleep apnea and immunity: Relationship of lymphocyte count and apnea hypopnea index

Objectives: The impact of chronic poor quality sleep on immunity as seen in obstructive sleep apnea (OSA) has not been evaluated. We aim to explore the relationship between lymphocytes, neutrophil, and total leukocyte counts with severity stratified apnea hypopnea index (AHI) in patients with OSA. Methods: A retrospective review of 119 patients' medical records diagnosed with OSA from October 2005 to July 2006 was performed. Data collected included demographics, comorbidities, total leukocyte, neutrophil, and lymphocyte count, body mass index (BMI), AHI, and Epworth sleepiness scores (ESS). Three AHI strata were constructed: mild (5-14), moderate (15-29), and severe (>30). Data were fitted in a linear regression model on which lymphocyte counts were the dependent variable against age, BMI, and AHI. An interaction product was also explored (age*BMI). All tests were two-sided; a P < 0.05 was considered statistically significant. We used Statview Version 5.01 (SAS Institute, Inc., Cary, NC) for the analysis. Results: Our study showed a linear association among AHI and BMI (P = 0.0017), but did not show association between lymphocyte count with either BMI (P = 0.33) or AHI (P = 0.90). A negative association between lymphocytes and age (P = 0.02) that persisted after adjustments for BMI and AHI was found. An interaction product (age*AHI) was not associated with lymphocyte count (P = 0.87). No correlation was found between peripheral blood count (P = 0.29) or neutrophil counts (P = 0.38) and AHI. Conclusion: We found OSA-induced sleep interruption not associated with lymphocyte, neutrophil, or peripheral blood cell count alterations. This information is useful for researchers evaluating the influence of sleep disruption on immunity.