High Fitness Levels Attenuate the Increased Risk of Hypertension Due to Low Socioeconomic Status in Middle-Aged Men: A Cohort Study

Hypertension (HTN) is the most common modifiable risk factor for cardiovascular disease, the leading cause of mortality globally. Several studies have documented a relationship between low socioeconomic status (SES) and increased risk of HTN.1 Pathways underlying the relationship include the presence of factors that are strongly related to lower SES such as lower levels of education, unhealthy lifestyles such as excessive alcohol consumption, limited access to health care, and higher prevalence of comorbid conditions.1 The health benefits of physical activity (PA) are wellestablished and these include the prevention of vascular diseases such as HTN.2 Cardiorespiratory fitness (CRF), considered to be the gold standard for assessing aerobic exercise capacity, is an indicator of cardiopulmonary function and can be increased though increased PA and exercise training.3 Cardiorespiratory fitness is an established and independent risk marker for vascular outcomes including hypertension.4 There is increasing evidence showing that higher levels of CRF can attenuate the increased risk of adverse outcomes due to other risk factors. For instance, we have previously shown that high CRF levels can attenuate (i) the increased risk of mortality due to SES,5(ii) the increased risk of sudden cardiac death due to low SES,6 (iii) the increased risk of pneumonia due to inflammation,7 and (iv) the increased risk of chronic obstructive pulmonary disease due to lowSES.8Several reports have also observed that the association of obesity with adverse outcomes is reduced on accounting for CRF levels.9</p

Cardiorespiratory Fitness, Inflammation, and Risk of Chronic Obstructive Pulmonary Disease in Middle-Aged Men: A COHORT STUDY

Purpose: Chronic obstructive pulmonary disease (COPD) is characterized by chronic lung inflammation. The relationship between cardiorespiratory fitness (CRF) and COPD has not been well characterized. We aimed to evaluate the independent and joint associations of inflammation (high-sensitivity C-reactive protein [hsCRP]) and CRF with COPD risk in a cohort of White men. Methods: Among 2274 men aged 42-61 yr at baseline, serum hsCRP level was measured using an immunometric assay and CRF was assessed using a respiratory gas exchange analyzer. The level of hsCRP was categorized as normal and high (≤3 and >3 mg/L, respectively) and CRF as low and high. We corrected for within-person variability in exposures using repeat measurements taken several years apart. Results: A total of 116 COPD cases occurred during a median follow-up of 26.0 yr. The age-adjusted regression dilution ratio of hsCRP and CRF was 0.57 (95% CI, 0.50-0.64) and 0.58 (95% CI, 0.53-0.64), respectively. Comparing high versus normal hsCRP levels, the multivariable-adjusted HR for COPD was 1.79 (95% CI, 1.20-2.68). The COPD risk decreased linearly with increasing CRF. The multivariable-adjusted HR for COPD per 1-SD increase in CRF was 0.75 (95% CI, 0.60-0.95). Compared with men with normal hsCRP-low CRF, high hsCRP-low CRF was associated with an increased COPD risk, 1.80 (95% CI, 1.12-2.89), with no evidence of an association for high hsCRP-high CRF and COPD risk, 1.35 (95% CI, 0.68-2.69). Conclusions: Both hsCRP and CRF are associated with COPD risk in middle-aged men. However, high CRF levels attenuate the increased COPD risk related to high hsCRP levels