Primary outcome measures
Symptoms and drug consumption were primary outcome measures. Symptoms
were validated based on the rhinoconjunctivitis total symptom score
(RTSS) questionnaire 21. Drug consumption was measured
using an MS questionnaire (see the Methods section in this article’s
supplementary information). The RTSS and MS were recorded by the
patients at the end of the birch pollen season (approximately June
1st) and at the end of the grass pollen season
(approximately September 1st) before treatment and for
the following three and four years altogether. The birch- and grass
pollen seasons are quite separate in Sweden.