Digit ratio as a risk factor for muscle dysfunction and acute exacerbation in patients with chronic obstructive pulmonary disease

OBJECTIVE: This study investigated the correlations of digit ratio (relative length of second and fourth fingers, 2D: 4D) and muscular strength with the progression of chronic obstructive pulmonary disease (COPD). METHODS: In total, 164 patients with COPD were enrolled in this prospective study. In all patients, the following parameters were measured: body compartments, pulmonary function, digit ratio (i.e., 2D: 4D), muscle function, and levels of partial pressure of oxygen and partial pressure of carbon dioxide in arterial blood. RESULTS: The right-hand digit ratio (R2D: 4D) was associated with dominant hand muscle dysfunction, non-dominant hand muscle dysfunction, and inspiratory muscle dysfunction. Logistic regression analysis showed that right-hand 2D: 4D (odds ratio [OR] = 0.01) and dominant hand muscle dysfunction (OR = 5.60) were significantly associated with past hospital admission. After adjustment for forced expiratory volume in 1 second, the following factors were associated with present acute exacerbations: right-hand 2D: 4D (OR = 0.01), dominant hand muscle dysfunction (OR = 3.83), expiratory muscle dysfunction (OR = 3.80), and inspiratory muscle dysfunction (OR = 3.61). CONCLUSIONS: Lower digit ratio may be associated with higher prevalence of muscle dysfunction. This factor could be used to identify patients with COPD who are at higher risk of acute exacerbation.