~Teachingcenter的醫學筆記~

參考自這裡的內容：https://www.google.com/patents/WO2010129860A2?cl=en

Stage I:
Mild risk
FEV1/FVC ratio less than 70% (比值小於70%)
FEV1 at least 80% of predicted value (至少還要有80%的預測值)
May have symptoms (可能已經有症狀了，但多半還算輕微)

Stage II:
Moderate risk
FEV1/FVC ratio less than 70% (比值當然還是小於70%，不然就沒病啦)
FEV1 about 50~80% of predicted value (約是50~80%的預測值)
May have chronic symptoms (病人會說有"老問題"，也通常是老了才會來看醫生)

Stage III:
FEV1/FVC ratio less than 70%
FEV1 about 30~50% of predicted value (只剩30~50%囉)
Have chronic symptoms (也是抱怨"老問題"，但開始會比較積極配合治療了)

Stage IV:
FEV1/FVC ration less than 70%
FEV1 less than 30% of predicted value (不太需要活動的病人)
or
FEV1 less than 50% of predicted value
with
Severe chronic symptoms (若是生活需要一點活動力，病人馬上就會不行了，雖然他們會很積極配合治療，但是都有點太晚了...)