Original Paper Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
Received: February 12, 2014 Accepted after revision: June 27, 2014 Published online: August 16, 2014
Predictive Factors for Clinical Response to Allergy Immunotherapy in Children with Asthma and Rhinitis Qiaoling Li Mengrong Li Wei Yue Jinsi Zhou Ruxia Li Jian Lin Yingchun Li Center for Asthma and Allergy Immunotherapy, The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, P.R. China
Abstract Background: To date, no predictive methods for the clinical response to allergy immunotherapy (AIT) are available. We sought to evaluate the pretreatment parameters used in diagnosing allergic asthma and/or rhinitis including allergen skin-prick test responses, serum specific and total IgE (sIgE and tIgE) levels and blood eosinophil counts, and to identify whether these can be used to predict clinical effectiveness in children treated with immunotherapy. Methods: This study involved 185 children who had undergone 3 years of standardized-quality house-dust mite subcutaneous immunotherapy. Clinical characteristics and laboratory parameters were analyzed. A multivariate unconditional logistic regression model and receiver operating characteristic curves were used. Predicted probabilities and predictive areas under the curve were calculated. Results: The clinical response to AIT was effective in 129/185 (69.7%) patients. Four variables were associated with clinical response by multivariate logistic analysis: tobacco smoke exposure [odds ratio (OR) 2.845 and 95% confidence interval (CI) 1.147–7.058; p =
© 2014 S. Karger AG, Basel 1018–2438/14/1643–0210$39.50/0 E-Mail [email protected] www.karger.com/iaa
0.024], a family history of atopy (OR 2.881 and 95% CI 1.240– 6.692; p = 0.014), a serum tIgE level ≥965 kU/l (OR 5.917 and 95% CI 2.320–15.089; p = 0.000) and an sIgE/tIgE ratio ≥6% (OR 0.336 and 95% CI 0.124–0.911; p = 0.032). The sensitivity and specificity of the area under the curve of the serum tIgE were higher than those of serum sIgE and sIgE/tIgE ratio alone. Conclusion: Tobacco smoke exposure, atopic family history, serum tIgE and sIgE/tIgE ratio were in significant correlation with clinical response to AIT in children, which may be helpful for patient selection before immunotherapy. The serum tIgE is superior to both the serum sIgE/tIgE ratio and sIgE levels alone in predicting clinical effectiveness. © 2014 S. Karger AG, Basel
Introduction
Asthma is the most common chronic lower respiratory disease in childhood throughout the world [1]. Allergy immunotherapy (AIT) is an effective treatment for allergic asthma and rhinitis, not only leading to a significant improvement in symptoms, airway hyperresponsiveness and medication requirements, but also changing the course of allergic disease and inducing allergen-specific immune tolerance [2]. Subcutaneous imCorrespondence to: Dr. Mengrong Li Center for Asthma and Allergy Immunotherapy, The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University 109# Xue Yuan West Road, Wenzhou 325027 (P.R. China) E-Mail lmrjohn @ 163.com
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
Key Words Allergy immunotherapy · Serum immunoglobulin E · Tobacco smoke exposure
Materials and Methods We retrospectively analyzed 521 child patients consecutively referred for AIT to the Center for Asthma and Allergy Immunotherapy at The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, China, between June 2007 and June 2013. All patients underwent standardized-quality (SQ) house-dust mite (HDM) immunotherapy administered by SCIT. Only 185 children of 4–14 years of age were enrolled in this study. They all fulfilled the criteria for persistent mild asthma according to the Global Initiative for Asthma (GINA) guidelines [9], and the diagnosis of persistent allergic rhinitis was based on criteria in the WHO Consensus Statement on Allergic Rhinitis and its Impact on Asthma (ARIA) [10]. All patients had a clinical history of at least 1 year of asthma and/or rhinitis related to HDM sensitization. This sensitization was confirmed on the basis of a positive skin-prick test (SPT) response to HDM extract (≥++) and the presence of serum specific IgE (≥ class 2) for both Dermatophagoides pteronyssinus (Der p) and D. farinea (Der f). None of the patients displayed contraindications to AIT, according to the international guidelines [11], and they all completed at least 3 years of SQ HDM immunotherapy administered via SCIT. We did not exclude patients with concomitant subcardinal perennial allergens, such as cat, dog dander, Alternaria sp. and cockroach, because approximately 80% of the screened population had multiple sensitizations.
Predictive Factors for Clinical Response to AIT
Before immunotherapy, blood was collected for the analysis of levels of serum tIgE and sIgE and blood eosinophil counts. Atopic family history, early-life environmental tobacco smoke exposure and the time of onset of respiratory symptoms were obtained from parents. Spirometry was conducted at baseline and once a year for the 3-year period of AIT, if the child cooperated. The study was approved by the ethical committee of the University Hospital and parents gave their written informed consent. Immunotherapy Specific SCIT was performed using Alutard R SQ Der p (ALKALBELLO AS, Hørsholm, Denmark), a standardized aluminum hydroxide-absorbed Der p. Treatment was initiated at a dose of 20 SQ units, increasing weekly until a target maintenance dose of 100,000 SQ units was reached. The whole treatment included a 15-week up-dosing (up to 100,000 SQ units) and a 3-year maintenance at a dose of 100,000 SQ units with injection intervals of 6 ± 2 weeks. The specialist would adjust the injection dosage properly according to the child’s reaction to the allergen preparations, but the cumulative allergen dosage for each child was about the same. Immunological Parameters Blood samples were taken before treatment and at the end of immunotherapy for serum sIgE and tIgE antibody assays. All analyses were performed in our central laboratory with the fluoroimmunoassay technique (UniCAP, Pharmacia Diagnostics, Uppsala, Sweden). Results were expressed in kilounits per liter (kU/l) for serum tIgE and in allergen-specific kilounits per liter (kUA/l) for sIgE. Serum tIgE levels were determined with a detection limit of 2 kU/l and an upper limit of 5,000 kU/l and serum sIgE levels were 0.35–100 kUA/l. The identical sIgE level was measured for any positive allergen presented in the SPT to confirm the concomitant subcardinal allergens, but we only analyzed and gave the explicit value of serum Der p-specific IgE which was the major allergen among our subjects. We used the following formula: sIgE/tIgE ratio = (sIgE/tIgE) × 100. Blood Eosinophil Counts The absolute blood eosinophil counts were determined with an automatic cytoanalyzer (Mindray, Shenzhen, China) with the normal value being ≤0.45 × 109/l. Skin-Prick Test SPTs with a standard aeroallergen panel included Der p, Der f, cat and dog epithelia, Alternaria sp., cockroach and grass, tree and weed pollens (ALK-ABELLO AS). A drop of each allergen extract was introduced via lancets into the skin on the volar side of the forearm. Histamine (10 mg/ml) and glycerinated saline were used as positive and negative controls. After 15 min, the mean of the largest diameter of the wheal and its perpendicular diameter was recorded as the response. A response of at least 3 mm greater than the saline control was deemed positive. We excluded the influential factors before the test and took an accurate record of each allergen and the wheal diameters for each patient. In addition, we calculated the skin index as the ratio of allergen wheal diameter divided by the histamine wheal size, so the SPT result for each allergen was also defined in terms of the skin index values: ≤0.5 (+), >0.5 and ≤1.0 (++), >1.0 and ≤2.0 (+++) and >2.0 (++++).
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
211
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
munotherapy (SCIT) was introduced into clinical practice early in the 20th century, and its efficacy has been confirmed by many double-blind, placebo-controlled trials and meta-analyses [3–5]. The clinical benefits of AIT are differentially weighed against safety issues, so recommendations from guidelines vary across countries. Although AIT does benefit many patients, it carries the risk of anaphylaxis and not all patients will experience an improvement. So, apart from searching for safer and more effective AIT strategies [6–8], there is also a need for identifying AIT-responsive and nonresponsive endotypes and phenotypes to be able to provide instructions based on clinical evidence for the selection of patients. In this study, we report the clinical results of 185 patients who received 3 years of SCIT at our immunotherapy center. We retrospectively examined the relationship of clinical characteristics and laboratory parameters for these patients, including the diameter of the wheal induced by the allergen, serum tIgE and sIgE levels, blood eosinophil counts and the clinical response to AIT. For the prediction of patients’ responses to AIT, we used receiver operating characteristic (ROC) curves to determine the sensitivity, specificity and predicted values for serum sIgE, serum tIgE and the serum sIgE/tIgE ratio, all obtained before the commencement of immunotherapy.
Assessment of Symptoms and Concomitant Medication The effectiveness of immunotherapy was based on the improvement of clinical symptoms and the reduction of concomitant drugs. We conducted a routine follow-up before each allergen injection and recorded the following in detail: nycterohemeral symptoms (rhinitis and pulmonary symptoms), concomitant medications (e.g. oral second-generation antihistamine, inhaled corticosteroids, leukotriene receptor antagonists and inhaled short-acting β2-agonists) and adverse reactions (immediate/late and local/systemic). All the children completed a Childhood Asthma Control Test or an Asthma Control Test every 2 or 3 months. The specialist adjusted the drugs based on individual symptoms (visual analog scale score) and asthma control levels. At the end of the immunotherapy, the children (and their parents) were asked the question: ‘Do you feel better than you did before therapy?’ The answer could be one of the following: a noticeable improvement, a mild improvement, no improvement or the disease became even worse. All the children had regular clinic follow-up for at least 2 years after the treatment, or telephone follow-up with the specialist for those who could not come to the clinic on schedule. The long-term follow-up included symptoms control, drug use and a brief assessment of the disease-related quality of life. The clinical response to AIT was considered to have been effective if: (1) when a patient entered the third year of immunotherapy, drugs were no longer needed or the dosage of concomitant medicine was reduced to 25% of that at baseline and (2) there was no need for any additional medication, symptoms became well-controlled and quality of life was satisfactory during the 2-year followup, and an overall assessment by the parents and children at the end of immunotherapy was a ‘noticeable’ or ‘mild’ improvement. If the conditions above were not met, the AIT was considered to have been ineffective. Pulmonary Function Measurements Lung function was measured before the immunotherapy with a JAEGER MasterScope Body automated system. Children were tested at least 24 h after the last inhaled short-acting bronchodilator. Values were expressed as a percentage of predicted values. Airway responsiveness to methacholine was assessed in subjects with FEV1 >80% predicted. The cumulative dose of methacholine (in micrograms) that produced a 20% decrease in FEV1 (PD20FEV1) which could represent airway responsiveness was calculated. There was no significant difference in FEV1 or PD20FEV1 between the children with different responses to AIT, as we showed in another article (unpubl. data). Statistical Analysis All the analyses were performed using computer software (SPSS version 18.0; SPSS, Chicago, Ill., USA). Data were reported as the arithmetic mean and 95% confidence interval (CI) for the mean when the distribution of the data was normal. When normality was rejected, data were examined after logarithmic transformation and presented as the geometric mean and the 95% CI for the
212
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
Table 1. Pretherapeutic basic characteristics of 185 patients with
SCIT Age, yearsa Male/female, n Atopic family history (yes/no), n Tobacco smoke exposure (yes/no), n Asthma/asthma + rhinitis/rhinitis, n Age at onset of symptoms, yearsa Response to AIT (effective/ineffective), n SPT wheal diameter, mma Categories of aeroallergena Serum tIgE level, kU/lb Serum sIgE level, kUA/lb Blood eosinophil count, cells × 109/la Serum sIgE/tIgE ratioa Systemic adverse reaction (yes/no), n
8.0 (7.6–8.5) 148/37 88/97 46/139 43/92/50 4.3 (3.9–4.6) 129/56 7.7 (7.2–8.3) 4.4 (4.1–4.7) 475.2 (407.4–553.4) 44.3 (38.0–51.3) 0.54 (0.47–0.61) 12.6 (11.3–14.0) 56/129
a
Mean (95% CI). Geometric mean after logarithmic transformation (95% CI).
b
geometric mean. The Kolmogorov-Smirnov test was used to evaluate the normal distribution. Group comparison tests were performed with the two-sided t test. Categorical variables between groups were compared by using the χ2 test and the nonparametric Mann-Whitney U test was used to determine significance. According to the results of the univariate analysis, the multivariate unconditional logistic regression model was used to determine the independent predicting factors for the AIT clinical response. For clinical practice, continuous variables would be changed to categorical variables, and the cut-off values were determined based on their ROC curve, area under the curve (AUC), sensitivity, specificity and Youden index score. After this, the logistic regression analysis was repeated. Stepwise multiple regression analysis (backward: Wald; entry: 0.05, removal: 0.10) was used. We expressed results as odds ratios (ORs) and their 95% CIs. For all tests, p < 0.05 was considered statistically significant and all p values quoted are twosided.
Results
Study Population and Basic Characteristics A total of 185 children (age 8.0 ± 3.0 years; 47 males and 138 females) meeting the criteria outlined above were enrolled our study. Fifty patients were affected by rhinitis only, and 135 were affected by asthma only or asthma combined with rhinitis. The response to AIT was considered effective in 129 (69.7%) patients and ineffective in 56 (30.3%). HDM was the most clinically problematic allergen; all patients were sensitized to it. There was polysensitization in 88.5%, with 21.2% sensitized to ≥5 aeroallergens. Patient characteristics are denoted in table 1. No Li/Li/Yue/Zhou/Li/Lin/Li
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
Visual Analog Scales Patients were instructed to grade their symptoms retrospectively (in the last 2–3 months) by marking these off on a straight line ranging from 0 (no symptoms) to 10 (the highest level of symptoms). Visual analog scales were evaluated for both rhinitis and asthma at the start of treatment and then every 2 or 3 months.
Table 2. Characteristics of patients with effective and ineffective clinical responses to AIT
Characteristic
Patients, n (%) Age, yearsa Males/females, n Males, % Females, % Atopic family history (yes/no), n Positive history, % No history, % Tobacco smoke exposure (yes/no), n Exposure, % No exposure, % Asthma/asthma + rhinitis/rhinitis, n Asthma, % Asthma + rhinitis, % Rhinitis, % Onset of symptoms, yearsa Categories of aeroallergena SPT wheal diameter, mma Serum tIgE level, kU/lb Serum sIgE level, kUA/lb Blood eosinophil count, cells × 109/l Serum sIgE/tIgE ratioa Systemic adverse reaction (yes/no), n Adverse reaction, % No reaction, %
Clinical response
p value
effective
ineffective
129 (69.7) 8.2 (7.6–8.7) 104/25 80.6 19.4 51/78 39.5 60.5 26/103 20.2 79.8 28/69/32 21.7 53.5 24.8 4.4 (4.0–4.8) 4.3 (4.0–4.6) 7.7 (7.0–8.3) 355.2 (301.4–418.7) 38.9 (32.3–46.8) 0.50 (0.43–0.58) 13.9 (12.4–15.4) 37/92 28.7 71.3
56 (30.3) 7.7 (7.0–8.4) 44/12 78.6 21.4 37/19 66.1 33.9 20/36 35.7 64.3 15/23/18 26.8 41.1 32.1 4.0 (3.4–4.6) 4.7 (3.9–5.5) 7.9 (6.8–9.0) 932.4 (722.9–1,202.3) 59.5 (47.0–75.2) 0.63 (0.49–0.75) 9.7 (7.2–12.2) 19/37 33.9 66.1
0.3 0.7
0.001
0.024
0.298
0.363 0.349 0.704 0.000 0.004 0.107 0.004 0.293
a
Mean (95% CI). Geometric mean after logarithmic transformation (95% CI).
fatal anaphylaxis occurred during the treatment. Details on adverse reactions and interventions are described elsewhere [12]. Univariate Analysis The independent-sample t test, χ2 test and MannWhitney U test were used to compare the differences between patients with and without an effective clinical response to AIT. When compared to patients with an effective clinical response to AIT, those without an effective response had a positive parental allergic asthma/rhinitis history (p < 0.01), higher percentages of early-life tobacco smoke exposure (p < 0.05), increased levels of serum tIgE (p < 0.0001) and sIgE (p < 0.005) and lower serum sIgE/ tIgE ratio percentages (p < 0.001; table 2). We did not find a relationship between the total dose received and the clinical response as all the patients in each group received an equal dose.
Multivariate Analysis A multivariate unconditional logistic regression model was used to determine the independently predicting factors for the clinical response to AIT. When 5 variables were included based on the results of the univariate analysis, only 3 of these displayed statistical differences, i.e. tobacco smoke exposure (OR 2.938 and 95% CI 1.177– 7.334; p = 0.021), atopic family history (OR 2.685 and 95% CI 1.173–6.145; p = 0.019) and tIgE levels (OR 0.998 and 95% CI 0.998–0.999; p = 0.000). Considering the colinearity of variables for clinical practice, continuous variables were changed to categorical variables, and the cutoff values were determined based on the combination of sensitivity, specificity, Youden index, ROC curve and AUC (fig. 1). Five variables were again included, and 4 still showed statistical differences by repeated logistic regression (table 3), indicating tobacco smoke exposure (OR 2.845 and 95% CI 1.147–7.058; p = 0.024), atopic
Predictive Factors for Clinical Response to AIT
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
213
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
b
Table 3. Multivariate analysis for independently predicting factors for the clinical response to AIT
Variable/predicting factor
Adjusted OR
95% CI
p value
Tobacco smoke exposure Atopic family history tIgE sIgE sIgE/tIgE ratio
2.845 2.881 5.917 1.976 0.336
1.147–7.058 1.240–6.692 2.320–15.089 0.773–5.049 0.124–0.911
0.024 0.014 0.000 0.155 0.032
The 3 continuous variables (i.e. serum tIgE and sIgE and sIgE/ tIgE ratio), were changed to categorical variables.
100
Diagnostic Performance for Prediction of Effective Clinic Response to AIT Using Basic Characteristics before Immunotherapy Figure 1 shows the sensitivity and specificity obtained by calculating ROC curves for serum tIgE and sIgE levels and serum sIgE/tIgE ratios and the pairwise comparisons of the ROC curves. As shown in table 4, the AUC was 0.772 for serum tIgE levels (95% CI 0.699–0.834), 0.695 for serum sIgE/tIgE ratio (95% CI 0.617–0.765) and 0.645 for serum sIgE levels (95% CI 0.566–0.719). When compared with each other, significant differences were found between the tIgE levels and the sIgE/tIgE ratio alone (p < 0.05) and the sIgE levels alone (p < 0.005). No significant difference was found between the sIgE/tIgE ratio and sIgE levels (p > 0.05). Our ROC analysis of the serum tIgE showed that a level of
Received: February 12, 2014 Accepted after revision: June 27, 2014 Published online: August 16, 2014
Predictive Factors for Clinical Response to Allergy Immunotherapy in Children with Asthma and Rhinitis Qiaoling Li Mengrong Li Wei Yue Jinsi Zhou Ruxia Li Jian Lin Yingchun Li Center for Asthma and Allergy Immunotherapy, The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, P.R. China
Abstract Background: To date, no predictive methods for the clinical response to allergy immunotherapy (AIT) are available. We sought to evaluate the pretreatment parameters used in diagnosing allergic asthma and/or rhinitis including allergen skin-prick test responses, serum specific and total IgE (sIgE and tIgE) levels and blood eosinophil counts, and to identify whether these can be used to predict clinical effectiveness in children treated with immunotherapy. Methods: This study involved 185 children who had undergone 3 years of standardized-quality house-dust mite subcutaneous immunotherapy. Clinical characteristics and laboratory parameters were analyzed. A multivariate unconditional logistic regression model and receiver operating characteristic curves were used. Predicted probabilities and predictive areas under the curve were calculated. Results: The clinical response to AIT was effective in 129/185 (69.7%) patients. Four variables were associated with clinical response by multivariate logistic analysis: tobacco smoke exposure [odds ratio (OR) 2.845 and 95% confidence interval (CI) 1.147–7.058; p =
© 2014 S. Karger AG, Basel 1018–2438/14/1643–0210$39.50/0 E-Mail [email protected] www.karger.com/iaa
0.024], a family history of atopy (OR 2.881 and 95% CI 1.240– 6.692; p = 0.014), a serum tIgE level ≥965 kU/l (OR 5.917 and 95% CI 2.320–15.089; p = 0.000) and an sIgE/tIgE ratio ≥6% (OR 0.336 and 95% CI 0.124–0.911; p = 0.032). The sensitivity and specificity of the area under the curve of the serum tIgE were higher than those of serum sIgE and sIgE/tIgE ratio alone. Conclusion: Tobacco smoke exposure, atopic family history, serum tIgE and sIgE/tIgE ratio were in significant correlation with clinical response to AIT in children, which may be helpful for patient selection before immunotherapy. The serum tIgE is superior to both the serum sIgE/tIgE ratio and sIgE levels alone in predicting clinical effectiveness. © 2014 S. Karger AG, Basel
Introduction
Asthma is the most common chronic lower respiratory disease in childhood throughout the world [1]. Allergy immunotherapy (AIT) is an effective treatment for allergic asthma and rhinitis, not only leading to a significant improvement in symptoms, airway hyperresponsiveness and medication requirements, but also changing the course of allergic disease and inducing allergen-specific immune tolerance [2]. Subcutaneous imCorrespondence to: Dr. Mengrong Li Center for Asthma and Allergy Immunotherapy, The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University 109# Xue Yuan West Road, Wenzhou 325027 (P.R. China) E-Mail lmrjohn @ 163.com
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
Key Words Allergy immunotherapy · Serum immunoglobulin E · Tobacco smoke exposure
Materials and Methods We retrospectively analyzed 521 child patients consecutively referred for AIT to the Center for Asthma and Allergy Immunotherapy at The Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, China, between June 2007 and June 2013. All patients underwent standardized-quality (SQ) house-dust mite (HDM) immunotherapy administered by SCIT. Only 185 children of 4–14 years of age were enrolled in this study. They all fulfilled the criteria for persistent mild asthma according to the Global Initiative for Asthma (GINA) guidelines [9], and the diagnosis of persistent allergic rhinitis was based on criteria in the WHO Consensus Statement on Allergic Rhinitis and its Impact on Asthma (ARIA) [10]. All patients had a clinical history of at least 1 year of asthma and/or rhinitis related to HDM sensitization. This sensitization was confirmed on the basis of a positive skin-prick test (SPT) response to HDM extract (≥++) and the presence of serum specific IgE (≥ class 2) for both Dermatophagoides pteronyssinus (Der p) and D. farinea (Der f). None of the patients displayed contraindications to AIT, according to the international guidelines [11], and they all completed at least 3 years of SQ HDM immunotherapy administered via SCIT. We did not exclude patients with concomitant subcardinal perennial allergens, such as cat, dog dander, Alternaria sp. and cockroach, because approximately 80% of the screened population had multiple sensitizations.
Predictive Factors for Clinical Response to AIT
Before immunotherapy, blood was collected for the analysis of levels of serum tIgE and sIgE and blood eosinophil counts. Atopic family history, early-life environmental tobacco smoke exposure and the time of onset of respiratory symptoms were obtained from parents. Spirometry was conducted at baseline and once a year for the 3-year period of AIT, if the child cooperated. The study was approved by the ethical committee of the University Hospital and parents gave their written informed consent. Immunotherapy Specific SCIT was performed using Alutard R SQ Der p (ALKALBELLO AS, Hørsholm, Denmark), a standardized aluminum hydroxide-absorbed Der p. Treatment was initiated at a dose of 20 SQ units, increasing weekly until a target maintenance dose of 100,000 SQ units was reached. The whole treatment included a 15-week up-dosing (up to 100,000 SQ units) and a 3-year maintenance at a dose of 100,000 SQ units with injection intervals of 6 ± 2 weeks. The specialist would adjust the injection dosage properly according to the child’s reaction to the allergen preparations, but the cumulative allergen dosage for each child was about the same. Immunological Parameters Blood samples were taken before treatment and at the end of immunotherapy for serum sIgE and tIgE antibody assays. All analyses were performed in our central laboratory with the fluoroimmunoassay technique (UniCAP, Pharmacia Diagnostics, Uppsala, Sweden). Results were expressed in kilounits per liter (kU/l) for serum tIgE and in allergen-specific kilounits per liter (kUA/l) for sIgE. Serum tIgE levels were determined with a detection limit of 2 kU/l and an upper limit of 5,000 kU/l and serum sIgE levels were 0.35–100 kUA/l. The identical sIgE level was measured for any positive allergen presented in the SPT to confirm the concomitant subcardinal allergens, but we only analyzed and gave the explicit value of serum Der p-specific IgE which was the major allergen among our subjects. We used the following formula: sIgE/tIgE ratio = (sIgE/tIgE) × 100. Blood Eosinophil Counts The absolute blood eosinophil counts were determined with an automatic cytoanalyzer (Mindray, Shenzhen, China) with the normal value being ≤0.45 × 109/l. Skin-Prick Test SPTs with a standard aeroallergen panel included Der p, Der f, cat and dog epithelia, Alternaria sp., cockroach and grass, tree and weed pollens (ALK-ABELLO AS). A drop of each allergen extract was introduced via lancets into the skin on the volar side of the forearm. Histamine (10 mg/ml) and glycerinated saline were used as positive and negative controls. After 15 min, the mean of the largest diameter of the wheal and its perpendicular diameter was recorded as the response. A response of at least 3 mm greater than the saline control was deemed positive. We excluded the influential factors before the test and took an accurate record of each allergen and the wheal diameters for each patient. In addition, we calculated the skin index as the ratio of allergen wheal diameter divided by the histamine wheal size, so the SPT result for each allergen was also defined in terms of the skin index values: ≤0.5 (+), >0.5 and ≤1.0 (++), >1.0 and ≤2.0 (+++) and >2.0 (++++).
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
211
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
munotherapy (SCIT) was introduced into clinical practice early in the 20th century, and its efficacy has been confirmed by many double-blind, placebo-controlled trials and meta-analyses [3–5]. The clinical benefits of AIT are differentially weighed against safety issues, so recommendations from guidelines vary across countries. Although AIT does benefit many patients, it carries the risk of anaphylaxis and not all patients will experience an improvement. So, apart from searching for safer and more effective AIT strategies [6–8], there is also a need for identifying AIT-responsive and nonresponsive endotypes and phenotypes to be able to provide instructions based on clinical evidence for the selection of patients. In this study, we report the clinical results of 185 patients who received 3 years of SCIT at our immunotherapy center. We retrospectively examined the relationship of clinical characteristics and laboratory parameters for these patients, including the diameter of the wheal induced by the allergen, serum tIgE and sIgE levels, blood eosinophil counts and the clinical response to AIT. For the prediction of patients’ responses to AIT, we used receiver operating characteristic (ROC) curves to determine the sensitivity, specificity and predicted values for serum sIgE, serum tIgE and the serum sIgE/tIgE ratio, all obtained before the commencement of immunotherapy.
Assessment of Symptoms and Concomitant Medication The effectiveness of immunotherapy was based on the improvement of clinical symptoms and the reduction of concomitant drugs. We conducted a routine follow-up before each allergen injection and recorded the following in detail: nycterohemeral symptoms (rhinitis and pulmonary symptoms), concomitant medications (e.g. oral second-generation antihistamine, inhaled corticosteroids, leukotriene receptor antagonists and inhaled short-acting β2-agonists) and adverse reactions (immediate/late and local/systemic). All the children completed a Childhood Asthma Control Test or an Asthma Control Test every 2 or 3 months. The specialist adjusted the drugs based on individual symptoms (visual analog scale score) and asthma control levels. At the end of the immunotherapy, the children (and their parents) were asked the question: ‘Do you feel better than you did before therapy?’ The answer could be one of the following: a noticeable improvement, a mild improvement, no improvement or the disease became even worse. All the children had regular clinic follow-up for at least 2 years after the treatment, or telephone follow-up with the specialist for those who could not come to the clinic on schedule. The long-term follow-up included symptoms control, drug use and a brief assessment of the disease-related quality of life. The clinical response to AIT was considered to have been effective if: (1) when a patient entered the third year of immunotherapy, drugs were no longer needed or the dosage of concomitant medicine was reduced to 25% of that at baseline and (2) there was no need for any additional medication, symptoms became well-controlled and quality of life was satisfactory during the 2-year followup, and an overall assessment by the parents and children at the end of immunotherapy was a ‘noticeable’ or ‘mild’ improvement. If the conditions above were not met, the AIT was considered to have been ineffective. Pulmonary Function Measurements Lung function was measured before the immunotherapy with a JAEGER MasterScope Body automated system. Children were tested at least 24 h after the last inhaled short-acting bronchodilator. Values were expressed as a percentage of predicted values. Airway responsiveness to methacholine was assessed in subjects with FEV1 >80% predicted. The cumulative dose of methacholine (in micrograms) that produced a 20% decrease in FEV1 (PD20FEV1) which could represent airway responsiveness was calculated. There was no significant difference in FEV1 or PD20FEV1 between the children with different responses to AIT, as we showed in another article (unpubl. data). Statistical Analysis All the analyses were performed using computer software (SPSS version 18.0; SPSS, Chicago, Ill., USA). Data were reported as the arithmetic mean and 95% confidence interval (CI) for the mean when the distribution of the data was normal. When normality was rejected, data were examined after logarithmic transformation and presented as the geometric mean and the 95% CI for the
212
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
Table 1. Pretherapeutic basic characteristics of 185 patients with
SCIT Age, yearsa Male/female, n Atopic family history (yes/no), n Tobacco smoke exposure (yes/no), n Asthma/asthma + rhinitis/rhinitis, n Age at onset of symptoms, yearsa Response to AIT (effective/ineffective), n SPT wheal diameter, mma Categories of aeroallergena Serum tIgE level, kU/lb Serum sIgE level, kUA/lb Blood eosinophil count, cells × 109/la Serum sIgE/tIgE ratioa Systemic adverse reaction (yes/no), n
8.0 (7.6–8.5) 148/37 88/97 46/139 43/92/50 4.3 (3.9–4.6) 129/56 7.7 (7.2–8.3) 4.4 (4.1–4.7) 475.2 (407.4–553.4) 44.3 (38.0–51.3) 0.54 (0.47–0.61) 12.6 (11.3–14.0) 56/129
a
Mean (95% CI). Geometric mean after logarithmic transformation (95% CI).
b
geometric mean. The Kolmogorov-Smirnov test was used to evaluate the normal distribution. Group comparison tests were performed with the two-sided t test. Categorical variables between groups were compared by using the χ2 test and the nonparametric Mann-Whitney U test was used to determine significance. According to the results of the univariate analysis, the multivariate unconditional logistic regression model was used to determine the independent predicting factors for the AIT clinical response. For clinical practice, continuous variables would be changed to categorical variables, and the cut-off values were determined based on their ROC curve, area under the curve (AUC), sensitivity, specificity and Youden index score. After this, the logistic regression analysis was repeated. Stepwise multiple regression analysis (backward: Wald; entry: 0.05, removal: 0.10) was used. We expressed results as odds ratios (ORs) and their 95% CIs. For all tests, p < 0.05 was considered statistically significant and all p values quoted are twosided.
Results
Study Population and Basic Characteristics A total of 185 children (age 8.0 ± 3.0 years; 47 males and 138 females) meeting the criteria outlined above were enrolled our study. Fifty patients were affected by rhinitis only, and 135 were affected by asthma only or asthma combined with rhinitis. The response to AIT was considered effective in 129 (69.7%) patients and ineffective in 56 (30.3%). HDM was the most clinically problematic allergen; all patients were sensitized to it. There was polysensitization in 88.5%, with 21.2% sensitized to ≥5 aeroallergens. Patient characteristics are denoted in table 1. No Li/Li/Yue/Zhou/Li/Lin/Li
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
Visual Analog Scales Patients were instructed to grade their symptoms retrospectively (in the last 2–3 months) by marking these off on a straight line ranging from 0 (no symptoms) to 10 (the highest level of symptoms). Visual analog scales were evaluated for both rhinitis and asthma at the start of treatment and then every 2 or 3 months.
Table 2. Characteristics of patients with effective and ineffective clinical responses to AIT
Characteristic
Patients, n (%) Age, yearsa Males/females, n Males, % Females, % Atopic family history (yes/no), n Positive history, % No history, % Tobacco smoke exposure (yes/no), n Exposure, % No exposure, % Asthma/asthma + rhinitis/rhinitis, n Asthma, % Asthma + rhinitis, % Rhinitis, % Onset of symptoms, yearsa Categories of aeroallergena SPT wheal diameter, mma Serum tIgE level, kU/lb Serum sIgE level, kUA/lb Blood eosinophil count, cells × 109/l Serum sIgE/tIgE ratioa Systemic adverse reaction (yes/no), n Adverse reaction, % No reaction, %
Clinical response
p value
effective
ineffective
129 (69.7) 8.2 (7.6–8.7) 104/25 80.6 19.4 51/78 39.5 60.5 26/103 20.2 79.8 28/69/32 21.7 53.5 24.8 4.4 (4.0–4.8) 4.3 (4.0–4.6) 7.7 (7.0–8.3) 355.2 (301.4–418.7) 38.9 (32.3–46.8) 0.50 (0.43–0.58) 13.9 (12.4–15.4) 37/92 28.7 71.3
56 (30.3) 7.7 (7.0–8.4) 44/12 78.6 21.4 37/19 66.1 33.9 20/36 35.7 64.3 15/23/18 26.8 41.1 32.1 4.0 (3.4–4.6) 4.7 (3.9–5.5) 7.9 (6.8–9.0) 932.4 (722.9–1,202.3) 59.5 (47.0–75.2) 0.63 (0.49–0.75) 9.7 (7.2–12.2) 19/37 33.9 66.1
0.3 0.7
0.001
0.024
0.298
0.363 0.349 0.704 0.000 0.004 0.107 0.004 0.293
a
Mean (95% CI). Geometric mean after logarithmic transformation (95% CI).
fatal anaphylaxis occurred during the treatment. Details on adverse reactions and interventions are described elsewhere [12]. Univariate Analysis The independent-sample t test, χ2 test and MannWhitney U test were used to compare the differences between patients with and without an effective clinical response to AIT. When compared to patients with an effective clinical response to AIT, those without an effective response had a positive parental allergic asthma/rhinitis history (p < 0.01), higher percentages of early-life tobacco smoke exposure (p < 0.05), increased levels of serum tIgE (p < 0.0001) and sIgE (p < 0.005) and lower serum sIgE/ tIgE ratio percentages (p < 0.001; table 2). We did not find a relationship between the total dose received and the clinical response as all the patients in each group received an equal dose.
Multivariate Analysis A multivariate unconditional logistic regression model was used to determine the independently predicting factors for the clinical response to AIT. When 5 variables were included based on the results of the univariate analysis, only 3 of these displayed statistical differences, i.e. tobacco smoke exposure (OR 2.938 and 95% CI 1.177– 7.334; p = 0.021), atopic family history (OR 2.685 and 95% CI 1.173–6.145; p = 0.019) and tIgE levels (OR 0.998 and 95% CI 0.998–0.999; p = 0.000). Considering the colinearity of variables for clinical practice, continuous variables were changed to categorical variables, and the cutoff values were determined based on the combination of sensitivity, specificity, Youden index, ROC curve and AUC (fig. 1). Five variables were again included, and 4 still showed statistical differences by repeated logistic regression (table 3), indicating tobacco smoke exposure (OR 2.845 and 95% CI 1.147–7.058; p = 0.024), atopic
Predictive Factors for Clinical Response to AIT
Int Arch Allergy Immunol 2014;164:210–217 DOI: 10.1159/000365630
213
Downloaded by: Wright State University 130.108.121.217 - 10/6/2014 1:11:44 PM
b
Table 3. Multivariate analysis for independently predicting factors for the clinical response to AIT
Variable/predicting factor
Adjusted OR
95% CI
p value
Tobacco smoke exposure Atopic family history tIgE sIgE sIgE/tIgE ratio
2.845 2.881 5.917 1.976 0.336
1.147–7.058 1.240–6.692 2.320–15.089 0.773–5.049 0.124–0.911
0.024 0.014 0.000 0.155 0.032
The 3 continuous variables (i.e. serum tIgE and sIgE and sIgE/ tIgE ratio), were changed to categorical variables.
100
Diagnostic Performance for Prediction of Effective Clinic Response to AIT Using Basic Characteristics before Immunotherapy Figure 1 shows the sensitivity and specificity obtained by calculating ROC curves for serum tIgE and sIgE levels and serum sIgE/tIgE ratios and the pairwise comparisons of the ROC curves. As shown in table 4, the AUC was 0.772 for serum tIgE levels (95% CI 0.699–0.834), 0.695 for serum sIgE/tIgE ratio (95% CI 0.617–0.765) and 0.645 for serum sIgE levels (95% CI 0.566–0.719). When compared with each other, significant differences were found between the tIgE levels and the sIgE/tIgE ratio alone (p < 0.05) and the sIgE levels alone (p < 0.005). No significant difference was found between the sIgE/tIgE ratio and sIgE levels (p > 0.05). Our ROC analysis of the serum tIgE showed that a level of
