The analogy between diagnosing hypertension and COPD is seriously flawed: 140/90 is not a ratio. Either high systolic BP or high diastolic BP increases the risk of death. Hypertension is a modifiable risk factor, not a disease like COPD. Thresholds for defining and treating high BP have always been based on increased risk of cardiovascular events and death.1
Blood glucose, BP, hemoglobin, electrolyte concentrations, and many other physiologic variables are controlled by multiple feedback mechanisms; therefore, normal values for these tests in healthy people change little with aging. This is not true for lung function or the elasticity, reserve, and resilience of many other tissues and organ systems. Only two things in life remain certain: physiologic aging leading to death and taxes.