The FEV1/FVC ratio compares air exhaled in the first second to total forced vital capacity, distinguishing obstructive from restrictive lung patterns. Lower ratios suggest obstruction (e.g., COPD). In underwriting, ratios, bronchodilator response, and stability over time inform ratings. Combined with symptoms and oxygen use, the ratio helps quantify functional impairment and mortality risk.

Field underwriting requests recent spirometry to document the ratio and bronchodilator response. If results show mild obstruction with good control, advisors advocate for credits. Worsening ratios or oxygen dependence push cases toward higher tables or declines. Timing applications after improvement can help.