Impact of Altitude on Erythrocyte Sedimentation Rate: A Cross-Sectional Study Using National Laboratory Data from Saudi Arabia.

Abstract

Background: The erythrocyte sedimentation rate (ESR) is a widely used haematological test that indirectly measures inflammation in the body. It is influenced by various factors, including age, sex, and physiological condition. Altitude is another critical factor due to its impact on red blood cell physiology and plasma protein composition. This study aims to evaluate how altitude influences ESR values in the Saudi Arabian population, considering demographic and clinical variables.

Methods: This cross-sectional study analyzed data from 158,539 participants collected from 42 commercial laboratory branches across 13 administrative regions in Saudi Arabia from 1 January 2015 to 31 December 2022. Participants were categorized based on city altitude and demographic characteristics including body mass index (BMI), alanine transaminase (ALT), chronic kidney disease (CKD), glycated haemoglobin (HbA1c), and thyroid-stimulating hormone (TSH) level. Univariate and multivariate logistic regression models were used to assess the factors influencing elevated ESR.

Results: The study analyzed 158,539 participants, with an equal sex distribution (49.9%) and a mean age of 40 years. The adjusted model results showed a CKD prevalence of 3%, with a higher prevalence at lower altitudes (3.8% at 0-500 meters). ESR levels were significantly influenced by sex, age, altitude, and clinical measurements. Males were less likely to have elevated ESR than females (odds ratio (OR) = 0.470, 95% confidence interval (CI): 0.440-0.510, p < 0.001). Older age was a strong predictor of elevated ESR, with those aged 90+ at a fourfold higher risk (OR = 4.540, 95% CI: 1.410-14.548, p = 0.011). Higher altitude was associated with reduced ESR, with an odds ratio of 0.660 (95% CI: 0.560-0.769, p < 0.001) above 2000 meters.

Conclusion: Altitude significantly impacts ESR values, highlighting the need for altitude-specific reference ranges to improve diagnostic accuracy in high-altitude regions. The results also emphasize the importance of considering demographic and clinical factors when interpreting ESR. These findings can guide clinicians in refining diagnostic algorithms and optimizing patient management strategies in diverse geographical settings.