Randomized controlled open study of sublingual immunotherapy
for respiratory allergy in real-life: clinical efficacy and more
Allergen immunotherapy (IT), together with allergen
avoidance and drug therapy, is a cornerstone in the
management of respiratory allergy (1). Immunotherapy is
capable of modifying the immunological response to the
offending allergens at the earliest stages, so that clinical
symptoms are progressively improved. The traditional
subcutaneous route is well established since several
decades and its efficacy has been confirmed in numerous
trials (2). The possible risk of severe (even fatal) adverse
events (3) encouraged the search for safer noninjection
approaches for administering IT (4). During the last
15 years, the sublingual route [sublingual immunotherapy
(SLIT)] was extensively investigated, and many controlled
trials confirmed its efficacy in respiratory allergy (5, 6). In
addition, both clinical trials and postmarketing surveil-
lance studies confirmed the optimal safety profile in both
adults and children (7–9). Based on these results, the most
recent official document, the ARIA guideline (10), valid-
ated the clinical use of SLIT also in paediatric patients.
At present, some concerns still exist about SLIT. First,
the overall number of patients studied in the controlled
trials is considered small; secondly, there is no informa-
tion about the adherence to the treatment (that is self-
administered); thirdly, it is not clear if the magnitude of
the efficacy of SLIT, can be considered clinically relevant
(11). In addition, subcutaneous IT displayed a preventive
effect on both the occurrence of new sensitizations (12)
and the onset of asthma (13), but such evidence still lacks
SLIT has been available in Italy (and other Mediter-
ranean countries, such as Spain and France) for more
than 10 years; therefore a solid clinical experience is
available in the field and a great number of patients
currently receive SLIT. Thus, we studied, in a randomized
fashion, a large population of patients with respiratory
allergy (rhinitis and/or asthma) because of common
allergens. After a baseline clinical evaluation, patients
were randomized to receive SLIT or drug treatment only.
Background: Some aspects of sublingual immunotherapy (SLIT) still need to
be addressed: magnitude of the clinical efficacy, effect on the bronchial
hyperreactivity adherence to treatment, preventive effect. We attempted to
clarify these points in a randomized open, controlled, two parallel group study in
a real-life setting.
Methods: Five hundred and eleven patients with allergic rhinitis with or without
intermittent asthma were randomized to drugs only or drugs + SLIT (rate 2 : 3)
for 3 years. The clinical score (symptoms + drug intake) was measured each
year during the allergen exposure. Pulmonary function test, methacholine
challenge and skin tests were performed at the beginning and at the end of the
study. Adherence to treatment was assessed by measuring the consumed extract.
Results: Three hundred and nineteen patients received SLIT and 192 drugs only.
Dropouts were 15% in the SLIT group and 12% in the controls. There was a
significant improvement of clinical scores in the SLIT group: baseline 147 ± 3.3,
first year 72.9 ± 1.3, second year 68.3 ± 1.8, third year 54.7 ± 2.8 (P < 0.0001
vs baseline). Control group: baseline 138 ± 2.3, first year 124.1 ± 3.7, second
year 111 ± 3.3, third year 121 ± 3.8 (P ¼ NS). Only four patients reported
systemic itching. Adherence was >80% in 72% and >60% in 18% of patients.
The number of patients with a positive MCh challenge decreased significantly
after 3 years only in the SLIT group. New skin sensitizations appeared in 38% of
the controls and in 5.9% of the SLIT patients (P ¼ 0.01).
Conclusion: Sublingual immunotherapy approximately halved the clinical scores
and significantly reduced the bronchial hyperreactivity. Similarly to subcuta-
neous immunotherapy, SLIT displayed a preventive effect on the onset of new
skin sensitizations. The adherence rate was quantitatively satisfactory.
M. Marogna1, I. Spadolini2,
A. Massolo3, G. W. Canonica4,
1Pneumology Unit, Cuasso al Monte, Macchi
Hospital Foundation, Varese;2Medical Department,
Anallergo S.p.A., Florence;3Section of Behavioural
Ecology, Ethology and Wildlife Management,
Department of Environmental Sciences, Siena
University;4Allergy & Respiratory Diseases,
Department of Internal Medicine, Genoa University,
Key words: adherence; bronchial hyperreactivity;
preventive effect; respiratory allergy; sublingual
Allergy & Respiratory Diseases
University of Genoa
L.go R.Benzi 10
Accepted for publication 5 January 2004
Allergy 2004: 59: 1205–1210
Printed in UK. All rights reserved
Copyright ? Blackwell Munksgaard 2004
The clinical efficacy and safety of SLIT were the primary
endpoints. Taking advantage of the large population, this
study could also elucidate some of the controversial
aspects: adherence to treatment, prevention of new
sensitizations, effect on bronchial hyperresponsiveness
and age-efficacy relationship.
Patients and methods
Overall study design
The study was randomized, open and controlled, with two groups
of allergic patients receiving SLIT plus drugs or drugs only for
The patients were evaluated in an observation period of 1 year
and then in a 3-year course of SLIT, by assessing the clinical scores
during the exposure to the causal allergen. Skin prick test and
pulmonary function test (PFT) with methacholine (MCh) challenge
were performed at baseline and after 3 years. A dropout analysis
and a quantitative assessment of the adherence to treatment were
also carried out. The study design is summarized in Fig. 1.
Patients and diagnosis
Outpatients seen at the Allergy Unit, Cuasso al Monte Hospital
(Varese, Italy), were enrolled. Inclusion criteria were:
• Clinical history of respiratory allergy at least in the past
2 years. Clinical criteria included recurrent episodes of
wheezing, cough or chest tightness (diurnal or nocturnal) and
typical rhinitis symptoms (sneezing, itching, rhinorrhea, con-
gestion) with or without eye itching and redness.
• Skin prick test positivity to one or more of the common
inhalant allergens, but moulds and pet dander.
• Age between 15 and 65 years.
• Intermittent asthma according to GINA criteria (14), and with
a FEV1within normal limits (i.e. >79% of predicted value).
Patients who had received previous courses of IT, with anatomical
abnormalities of the upper respiratory tract or suffering from
malignancies or systemic immunological disorders were excluded
from this study.
The patients were followed up for 1 year with a standard phar-
macological treatment, then they were randomized, following a
computer-generated list, to receive SLIT or drug therapy alone
Skin test and PFT
Prick tests were performed according to international guidelines
(15) with commercial standardized extracts (Alk Abello, Lainate,
Milan, Italy) of the following allergens: house dust mites, grasses,
parietaria, cat dander, dog dander, birch, olive, ragweed, mug-
worth, Alternaria and Cladosporium. Tests were carried out on the
forearm, using positive (histamine 1%) and negative (saline) con-
trols for comparison. The results were expressed as the mean of the
major diameter of the wheal plus its orthogonal. Reactions >5 mm
were considered positive.
Pulmonary function tests were performed by a computerized
spirometer (Masterlab Yaeger, Wurtzburg, Germany). The MCh
challenges were carried out when the patients were asymptomatic
and free of medications (inhaled and oral) for at least 15 days, and
they were performed in each patient in the same period of the year.
A dosimeter (Yaeger), activated by the inhalatory effort was used
and increasing doses of MCh were administered, starting from 125
to 1200 lg. The test was considered positive (MCh+) if the dose
causing a fall of 20% of FEV1was equal or <1200 lg (16, 17).
Specific IT and pharmacological treatment
SLIT was prescribed only for the clinically relevant allergen, based
on clinical history and skin positivity. In a few patients with mul-
tiple sensitizations, the main causal allergen was not immediately
clear. In those cases, a nasal provocation test was carried out, and
the allergen eliciting symptoms at the lowest doses was chosen (18).
For ethical reasons (expected better outcome of SLIT) the rand-
omization was set at 3 : 2 in favour of SLIT.
The SLIT (Anallergo, Florence, Italy) was prepared as a
glycerinated solution to be administered as sublingual drops in the
morning, after the patient had fasted. The patients were carefully
instructed by the physician about the self-administration, and
detailed written instructions were provided. All the extracts were
standardized through combined radioallergosorbent test (RAST)-
inhibition and bioequivalence method: the potency was expressed
as RAST-Units/ml (RU/ml). The build-up phase, of about
50 days, involved the administration of the extract at progressively
increasing concentrations (100, 300, 1000, 3000 RU/ml). In the
maintenance phase, five drops from the 10 000 RU/ml vial were
given three times a week. The SLIT was administered continu-
ously for approximately of 3 years. In those patients receiving
pollen IT a dose reduction by one-third was performed in the
The mean cumulative dose per year was about 390 mcg Der p 1/
Der p 2, 70 mcg Phl p 1 and Par j 1 and 100 mcg Bet v 1. This
corresponds to about 10 times the dose administered in a corres-
ponding subcutaneous course with the same product.
The following medications were allowed: nasal cromolyn, oral
antihistamines (loratadine or cetirizine 10 mg, 1 tablet/day), intra-
nasal corticosteroid (beclometasone dipropionate 1 puff b.i.d.),
inhaled albuterol (100 mcg two to three puff on demand).
Clinical diary card
Patients were instructed to fill a diary card during the periods of
significant exposure to their causal allergens. The diaries were
Year 1 Year 2 Year 3
Figure 1. Study design. MCh, methacholine challenge.
Marogna et al.
recorded in: November to February for mites, March and April
for birch, May and June for grasses and parietaria, July–October
for ragweed and mugwort. The following symptoms were consid-
ered: nasal itching, sneezing, rhinorrhea, obstruction, cough,
wheezing, and conjunctival itching/redness. Each symptom was
scored as 0 ¼ absent, 1 ¼ mild, 2 ¼ moderate, 3 ¼ severe. In
addition, each dose of each rescue drug was scored as 1. For each
patient, the monthly sum of drugs + symptoms was obtained, the
mean sum of the months in each period of observation (2–
4 months depending on the allergen) was used for statistical ana-
Safety and adherence
Patients were required to record on a proper diary card, at each
dose, any local or systemic adverse event possibly related to SLIT
administration and the time of onset. For convenience, the reactions
were subdivided into: systemic (asthma, rhinitis, urticaria, angi-
oedema, generalized itching, diarrhoea, vomiting) and local (oral
itching/swelling, oedema of the tongue). Any other suspected
adverse event had to be described. The patients were instructed to
contact the centre when they needed medical advice.
Adherence was assessed by measuring with a pipette the
remaining volume of extract in the returned vials and comparing it
with the expected amount of extract consumed during a given
period of treatment. The volume of the extract actually consumed
by each patient was expressed as a percentage of the expected
consumption. Using this method, adherence was graded as: poor
(<40%); insufficient (<60%); good (<80 and >60%); excellent
Comparisons between frequencies have been tested by Pearson chi-
squared, whilst the Mann–Whitney U-test was performed to verify
differences between the two groups (19, 20) both regarding the mean
patients? age and the symptom score at the four timepoints. The
probability level has been computed using a complete randomiza-
tion method (permutation or exact test; Pexact) or by a Monte Carlo
(21) simulation based on a 10 000 sampled tables (PMonte Carlo)
when computation was not possible. The type I error (a) has been
set at the 0.01 level. The means (age, symptom scores, etc.) have
been reported with the standard error of mean (±SE). The General
Linear Model (GLM) for repeated measures (22) was used to assess
the effect of age (< or ‡18 years) and gender as random factors on
symptom scores and their variations. All the statistical analyses
have been computed using the Statistical Package for Social
Sciences ver. 10.05 (SPSS?, SPSS Inc., Chicago, IL).
Five hundred and eleven patients completed the baseline
assessment (1-year observation) and were randomized
(through a computer-generated list) to receive SLIT (319
patients) or drug therapy alone (192 patients). The two
groups were homogenous for all demographic character-
istics but sex. The clinical and demographic characteris-
tics of the patients are summarized in Table 1.
Each patient received SLIT only for one allergen as
follows: 166 mites, 89 grasses, 56 birch, six parietaria and
Drop-outs and safety
During the 3 years of the controlled study 70 patients
dropped-out: 48 patients (15%) in the SLIT group and 22
patients (12%) in the control group. The overall differ-
ence between the two groups was not significant (v2¼
4.05; d.f. ¼ 1; PMonte Carlo¼ 0.051). Noteworthy, 14 of
22 (63.6%) control patients vs nine of 48 (18.7%) SLIT
patients dropped out because of intolerable worsening of
symptoms (v2¼ 29.096; d.f. ¼ 1; PMonte Carlo< 0.001),
requiring more aggressive treatment including systemic
corticosteroids. The five dropouts because of adverse
events in the SLIT group were: three oral itching, one
asthma and one abdominal pain. Thus, 271 patients of
the SLIT group and 170 patients of the control group
could be analysed at the end of the 3-year period of
observation (Fig. 2).
During the 3 years of SLIT treatment, four of 271
patients (1.5%), reported one episode of generalized
itching (without apparent skin lesions) within 30 min
after taking the dose. These four adverse events appeared
during the maintenance phase and self-resolved without
therapy in <2 h. Those patients were instructed to
temporarily halve the dose, then to gradually increase it
again. This intervention allowed tolerating the maximum
The monthly clinical score differed significantly at each
time point, including baseline, as shown in Fig. 3. The
symptom scores significantly improved only in the SLIT
group, where they approximately halved since the first
year (baseline 147 ± 3.3, first year 72.9 ± 1.3, second
year 68.3 ± 1.8, third year 54.7 ± 2.8; P < 0.0001 vs
baseline). No change was seen in the control group
(baseline 138 ± 2.3, first year 124.1 ± 3.7, second year
111 ± 3.3, third year 121 ± 3.8; P ¼ NS at all times).
Also the inter-group comparisons showed a significant
difference at the all time points (Fig. 3). The results of the
GLM for repeated measures showed that the proportion
of reduction of clinical scores because of treatment was
significantly differentinthe 3-yearperiod (GLM
Table 1. Demographic and clinical data at baseline (randomization)
SLIT ControlTest d.f. PMonte Carlo
Rhinitis + asthma
Sensitized to HDM
Sensitized to pollens 153 (48.0%)
1.29 (180/139) 1.70 (121/71) v2¼ 5.593
128 (40.1%)72 (37.5%) v2¼ 0.938
191 (59.9%)120 (62.5%)
166 (52.0%) 98 (51.0%) v2¼ 0.127
U ¼ 22 296.5
W ¼ 59 152.5
U and W, values of the Mann–Whitney test; v2, chi square estimate; d.f., degree of
freedom of the chi-square test; PMonte Carlo, P-values using the Monte Carlo esti-
SLIT in real life
within-subjectseffects: F ¼ 237.077;d.f. ¼ 3;P < 0.001).
Interestingly, in the subgroup of patients with age
<18 years the reduction of symptom scores was signifi-
cantly more pronounced than in patients aged ‡18 years
effect: F ¼ 212.183, d.f. ¼ 1; P ¼ 0.002). No difference in
clinical efficacy among allergens could be detected.
The adherence to the prescribed SLIT treatments (inde-
pendent of the allergen extract used) over the 3-year
period resulted as follows: excellent (>80%) in 195 of 271
(72%) patients, good (from 60 to 80%) in 49 of 271
(18%) cases, and poor or insufficient in 27 of 271 (10%)
Pulmonary function test and methacholine challenge
The pulmonary function remained within the normal
range (FEV1>80%) at the interim visits and at the final
visit in all patients and no case of persistent asthma
(needing for stable therapy with inhaled steroids)
appeared. There was a significant evolution of the
MCh challenge results (Table 2). In the SLIT group,
there was a significant reduction of MCh positive cases,
from 160 of 271 patients at baseline (either rhinitics and
asthmatics) to 63 of 271 at the third year (v2¼ 143.572;
d.f. ¼ 1; PMonte Carlo< 0.001), whereas no significant
reduction was observed in the control group where the
MCh+ patients were 106 of 170 at baseline and 95 of
170 at the third year (v2¼ 3.032; d.f. ¼ 1; PMonte
Mean monthly score
2nd Year3rd Year
Figure 3. Mean monthly symptom scores in SLIT and control
patients at baseline, after 1, 2 and 3 years of treatment. Above
the bars are reported the P-values for the Mann–Whitney test
Mean, 95% CI
Percentage reduction of climical score
Figure 4. Clinical improvement in each year of treatment
(expressed as the proportion of reduction from the baseline
scores) in paediatric and adult patients.
1st year: 1dropouts
1 no improvement
4 spont. discontin.
11 protocol deviation
5 side effects
5 no improvement
2 spont. discontin.
8 protocol deviation
3rd year:12 dropouts
3 no improvement
1 spont. discontin.
8 protocol deviation
1st year: : 9 dropouts
5 no improvement
1 spont. discontin.
3 protocol deviation
2nd year: 6 dropouts
5 no improvement
1 protocol deviation
3rd year: 7 dropouts
4 no improvement
1 spont. discontin.
2 protocol deviation
Figure 2. Study flowchart and dropout analysis.
Table 2. Evolution of disease and bronchial hyperreactivity. Absolute number of
patients and percentage in parentheses
Pure rhinitis (MCh))
Hyperreactivity (MCh+) 160 (59.1)
111 (40.9) 208 (76.7) <0.001
64 (37.6) 75 (44.1) NS
106 (62.4) 95 (55.9)
P, P-value for the Pearson chi-square test.
Marogna et al.
At the end of the treatment period, one or more new skin
sensitizations with respect of those existing at the time of
randomization appeared in 16 of 271 (5.9%) patients of
the SLIT group and in 64 of 170 (38%) patients of the
control group (v2¼ 70.885; d.f. ¼ 1; PExact< 0.001).
The present guidelines, based on rigorous experimental
studies, have accepted SLIT as a suitable treatment, and a
recent meta-analysis study (6), further confirmed its
efficacy in allergic rhinitis. The published clinical trials
involved a limited number of patients, because of the need
for very selected and homogeneous subjects. The strict
selection allowed to study some specific aspects, such as
the immunological effects at cellular and humoral level
(23–25), but necessarily limited the clinical information.
For instance, the magnitude of the clinical effect was
reported to range between 20 and 60%, and the preven-
tion on the onset of new sensitizations could not be
assessed. In fact, this latter effect could be demonstrated
for subcutaneous IT in retrospective studies, involving
hundreds of patients (26, 27). Moreover, the available
trials do not provide information on the effect of SLIT on
bronchial hyperreactivity, and the adherence, which is a
major concern, was never quantitatively assessed (5, 28).
Studying a large number of patients in a real situation
can provide a more reliable quantitative evaluation of the
effectiveness of the treatment, and allow to better define
other clinical aspects, such as the effect on the onset of new
sensitizations. These are the reasons why we evaluated the
outcome of SLIT in a relatively unselected population and
ina real-life setting. In our study the clinical scores showed
an improvement of about 50% vs baseline values, since the
first year of treatment, despite the scores were significantly
higher in the SLIT group at baseline. Also, It is important
to notice that the clinical effect of SLIT was greater in
support to the believe that IT does better in younger.
Another important finding was the significant modifi-
cation of the nonspecific bronchial hyperresponsiveness to
MCh, which is considered as a distinctive feature of
asthma (29). This is in agreement with other observations
made with both SLIT (30) and injection IT (31) in smallest
groups. The prevention of the onset of new sensitizations
suggests that SLIT, similarly to the subcutaneous route,
acts as a biological response modifier. This fact fits with
the recently demonstrated long-lasting effect of SLIT after
its discontinuation (32). In the controlled trials so far
available, the adherence to treatment was generically
reported as ?satisfactory?, but no systematic assessment
was indeed performed. Our quantitative data probably
represent a more realistic evaluation of the adherence to
SLIT, that did not differ from that reported for drugs (33).
Of course, measuring the volume of the remaining extract
does not warrant that the patients really took the vaccine,
but this approach obviously avoids an overestimation of
the adherence: if the remaining volume of the vaccine is
higher than expected we can be assured that the patient
has not fraudly discharged the extract.
It can be argued that in the present study no immu-
nological parameter [e.g. allergen specific immunoglob-
ulin (Ig)G or IgE, specific reactivity, skin reactivity] was
investigated, but is also true that the clinical improvement
is the only outcome available to define the efficacy of IT.
The so-called ?paraclinical? measures can be considered as
an adjunct, but cannot replace the clinical assessment.
Another possible flaw of the present study is the open
design. We decided to a have large number of subjects in
order to clearly assess the clinical parameters, and
keeping more than 500 patients in a 3-year double-blind
study is difficult to make. Indeed, the patients knew that a
new treatment was added, and therefore a placebo effect,
that may account for up to 30% of the measured outcome
(34), could be expected. Nevertheless, it must be consid-
ered that in our study the change in clinical scores was
>50% and it cannot be explained as a simple psycho-
logical effect. In addition, the change in the number of
skin positivities and MCh reactivity are unlike to be
affected by the placebo effect.
In conclusion, the above results further confirm the
clinical efficacy and effectiveness of SLIT, even if evalu-
ated in a real-life setting. In addition, SLIT was globally
associated with an optimal adherence rate and proved
capable of preventing the onset of new sensitizations.
This work was partly supported by ARMIA (Associazione Ricerca
Malattie Immunologiche e Allergiche).
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