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.