Cross-Sectional Analysis: Waist-to-Hip Ratio and Oxygen Saturation Association in Men Exposed to Long-Term Chronic...

Background/Objectives: Long-term chronic intermittent hypobaric hypoxia (CIHH) is a common occupational exposure among high-altitude workers, particularly miners in northern Chile. This condition consists of working several days above 2500 m followed by rest at sea level, maintaining this cycle for years, which generates physiological alterations. This study analyzed associations among anthropometric indices and biomedical conditions in miners chronically exposed to long-term CIHH. Methods: This study was a cross-sectional analysis of 120 healthy Chilean male miners working at altitudes above 4400 m under a 7-day work/7-day rest schedule. Eligibility required ≥5 years of CIHH exposure and absence of cardiopulmonary disease, hypertension, diabetes, or oxygen therapy use. The assessments at altitude included oxygen saturation (SpO₂), blood pressure, heart rate, hematological parameters, metabolic parameters, and waist-to-hip ratio (WHR); measurements were obtained 18 h after arrival at altitude. WHR, BMI, SpO₂, and biomedical variables were collected following standardized procedures. Descriptive statistics and group comparisons were performed with Student's t-test or the Wilcoxon test, with statistical significance set at p < 0.05. Normality assumption was assessed using the Shapiro-Wilk test. The association between WHR and SpO₂ was estimated using linear regression, with WHR scaled so that one unit corresponds to a 0.1-unit increase. Adjusted models included BMI, age, and years working under CIHH. Effect sizes and 95% confidence intervals (CIs) were reported. All statistical analyses were performed in the R programming language. Results: Mean SpO₂ was 89.07 ± 0.50% and mean WHR was 0.94 ± 0.01. In unadjusted comparisons, workers with WHR > 0.94 had lower SpO₂ than those below the threshold (88.8 ± 0.54 vs. 90.41 ± 0.50; p = 0.031). In adjusted models, the WHR-SpO₂ association was small and imprecise (β per 0.1-unit WHR = -0.67 pp; 95% CI -2.08 to 0.74). Hemoglobin showed an independent association with SpO₂, while other metabolic variables did not materially contribute. Conclusions: SpO₂ showed a modest inverse association with WHR in long-term CIHH workers. Even small saturation decreases may matter at high altitude. Combined WHR-SpO₂ monitoring may aid occupational surveillance, though longitudinal studies are needed to establish meaningful risk thresholds.