Usually very little. Mild to moderate, well-controlled asthma is frequently underwritten at standard or even preferred rates. Severe asthma with hospitalisations or oral steroid use is assessed more carefully.
Asthma and COPD are both respiratory conditions and they are underwritten nothing like each other. Asthma is generally the mildest respiratory impairment a carrier sees.
What separates mild from severe
Carriers grade it on how much treatment is needed to keep it controlled, and on what happens when it is not:
- Mild — occasional rescue inhaler, no maintenance medication, no attacks needing treatment. Often no effect on the rate class at all
- Moderate — daily maintenance inhaler, good control, no recent emergency care. Standard rates are common
- Severe — frequent oral steroid courses, emergency visits, hospital admissions, or a history of intubation. This is where ratings appear
The items that actually move it
Hospital admissions and any history of intubation carry the most weight, because they indicate the condition has been life-threatening rather than merely present. Repeated courses of oral prednisone signal poor control.
Smoking alongside asthma compounds badly, for the same reason it does in COPD.
What to have ready
Your current medication list, the date of your most recent attack requiring treatment, and any spirometry results. Childhood asthma that resolved is worth stating as resolved — otherwise it reads as current.
The full treatment of this topic is on COPD and respiratory.