Allergen immunotherapy associated with less nasal inhaler use in the short term

Key takeaways:

• Patients were treated for grass, birch and/or mugwort pollen allergy.
• Patients with persistent allergic rhinitis reported even less nasal inhaler use during the first 5 years of immunotherapy.

Patients treated with allergen immunotherapy for pollen used less nasal inhaler medication during their first 5 years of treatment than patients who did not use immunotherapy, according to a study published in Allergy.

However, this difference in nasal inhaler medication use did not persist after 5 years of immunotherapy, Peter Bager, PhD, MS, senior researcher, department of epidemiology research, Statens Serum Institut, and colleagues wrote.

The 7,760 patients (43.9% women) who used intranasal corticosteroids (INS) for their allergic rhinitis before beginning allergen immunotherapy included 4,373 treated for grass, 1,374 treated for birch, 60 treated for mugwort and 2,134 treated for a combination of these allergens.

The researchers matched these patients against a group of 15,520 patients (44.3% women) with allergic rhinitis who did not receive allergen immunotherapy. Also, 70% of the immunotherapy group halted treatment after 4 years, 87% stopped after 5 years and 94% stopped after 6 years.

Proportions of patients who used nasal inhalers increased and then peaked in the 3 years prior to baseline before dropping immediately after in the treatment and control groups alike, the researchers said.

Compared with the control group, the treatment group had smaller proportions of patients who used nasal inhalers through 5 years after baseline, including odds ratios of 0.84 (95% CI, 0.81-0.88) between 0 and 2 years after baseline and 0.88 (95% CI, 0.84-0.92) between 3 and 5 years after baseline.

But these proportions in the treatment group remained constant later whereas proportions in the control group fell. So, the treatment group had relatively higher proportions of nasal inhaler users later, including odds ratios of 1.03 (95% CI, 0.97-1.08) between 6 and 9 years after baseline and 1.18 (95% CI, 1.11-1.26) between 10 and 18 years after baseline.

The researchers reported that patterns of eyedrop usage between the treatment and control groups resembled the patterns in INS usage.

The treatment group had a higher proportion of patients who used oral antihistamines than the control group with differences that mostly grew over time from baseline, including odds ratios of 1.24 (95% CI, 1.18-1.29) at 0 to 2 years, 1.19 (95% CI, 1.14-1.25) at 3 to 5 years, 1.29 (95% CI, 1.23-1.36) at 6 to 9 years and 1.44 (95% CI, 1.35-1.54) at 10 to 18 years.

Patients who used nasal inhalers for 2 of the 3 years before baseline, including 30.5% of the treatment group, had outcomes that resembled the overall findings.

However, the treatment group had a lower proportion of patients who used nasal inhalers for all 3 of the pre-baseline years and then continued to use them through 9 years after baseline, compared with the control group, but these proportions evened out after 10 years.

Odds ratios for these patients included 0.59 (95% CI, 0.54-0.64) from 0 to 2 years, 0.64 (95% CI, 0.59-0.71) from 3 to 5 years, 0.82 (95% CI, 0.75-0.91) from 6 to 9 years and 0.95 (95% CI, 0.84-1.08) from 10 to 18 years.

Among the patients who only used nasal inhalers during 1 of the 3 years before baseline, including 44.9% of the treatment group, the treatment group saw a larger proportion of patients who were using nasal inhalers at 3 years after baseline.

Usage of eyedrops and oral antihistamines had similar patterns when the researchers stratified results based on pre-baseline use of nasal inhalers.

When the researchers analyzed the patients who used a nasal inhaler during the previous pollen season, the treatment group had a smaller proportion of patients who used a nasal inhaler after baseline compared with the control group. In other words, the researchers said, these patients tended to stop using their nasal inhalers.

Odds ratios for these patients included 0.76 (95% CI, 0.72-0.79) for 0 to 2 years, 0.86 (95% CI, 0.81-0.93) for 3 to 5 years, 0.94 (95% CI, 0.87-1.02) for 6 to 9 years and 0.94 (95% CI, 0.86-1.04) for 10 to 18 years.

But when the researchers analyzed the patients who did not use a nasal inhaler during the previous pollen season, the treatment group had a higher proportion of patients who used a nasal inhaler after baseline, compared with the control group.

Or, the researchers said, these patients tended to start using a nasal inhaler when they had not used one during the previous pollen season.

Odds ratios for these patients included 1.02 (95% CI, 0.95-1.1) from 0 to 2 years, 1.11 (95% CI, 1.04-1.19) from 3 to 5 years, 1.23 (95% CI, 1.15-1.32) from 6 to 9 years and 1.33 (95% CI, 1.23-1.44) for 10 to 18 years.

There were similar proportions when the researchers assessed eyedrop and oral antihistamine use, they said, even after they stratified for use before the baseline.

Sensitivity analyses found similar results for patients who were treated for only one of the three allergens or with the recommended 3 years of treatment, which included at least four filled prescriptions in the first 3 years.

Patients who were treated for multiple allergens had a smaller proportion who used nasal inhalers during the first 10 years after baseline compared with the control group, but after that, the treatment and control groups had equal proportions.

Further, the researchers reported almost equal use of the different Anatomic Therapeutic Chemical main anatomical groups of medications, except for allergen immunotherapy prescriptions, among the treatment and control groups each year.

Both groups reported nearly equal long-term use of general practitioner services as well, the researchers added, except during the first 5 years after baseline when general practitioner services related to allergen immunotherapy could not be excluded.

Based on the number of prescribed allergic rhinitis medication packages reported, the researchers said, less than 50% of the cohort used at least one nasal inhaler during each pollen season, and less than 20% used at least two.

Overall, the researchers said, patients using immunotherapy for pollen allergies used nasal inhalers less during their first 5 years of treatment than patients not on immunotherapy, particularly among patients with persistent allergic rhinitis, but these differences did not persist later in their treatment.

The researchers also called for further research to determine if greater use of allergen immunotherapy among patients with allergic rhinitis could reduce disease burden and costs.