Both rhinitis (ARIA) and asthma (GINA) guidelines recommend allergen-specific immunotherapy (SIT) tailored to the specific levels of severity of each disease. Real world studies evaluating congruence between these recommendations and prescribing practice in the single patient with comorbidity are lacking.

An observational polycentric study was carried out in 518 patients recruited from 34 allergy centers throughout Italy. A questionnaire was administered to each consecutive patient over a span of four months.

Taking into account guideline recommendations for both diseases, concomitant in the same patient, three subsets resulted: patients not eligible for SIT (11%); patients eligible for SIT for one disease only (60%); patients eligible for SIT for both diseases (29%). SIT was prescribed in 257 (49.6%) subjects. The level of SIT prescription was about 50% in all three groups. Consistent with the ARIA guidelines, a correlation between the prescription of SIT and the severity of rhinitis was documented (r=0.87; p=0.001). An association with asthma severity was found (p=0.02), but the trend was inconsistent with the GINA recommendations. Young age was the most important factor for SIT prescription both in the eligible for one disease and in the eligible for both diseases subset. The tendency towards worsening of symptoms was a factor for SIT in the eligible for one disease subset.

In mite allergic patients with rhinitis and asthma comorbidity, the severity of rhinitis and the young age are the most important factors driving the SIT prescription. The congruence of SIT prescription was better for the ARIA than GINA guidelines.