Food allergen sensitization patterns in a large allergic population in Mexico.

INTRODUCTION AND OBJECTIVES: Although food allergy is recognized as a growing worldwide public health problem, there continues to be limited data on prevalence rates in developing and emerging countries. Most prevalence estimates are based on self-reports, with only few studies using objective assessments. The aim was to analyze the frequency of sensitization to food allergens by serum specific IgE in a large group of unselected allergic patients in Mexico. MATERIALS AND METHODS: We analyzed data registries from patients of all ages with suspected food allergy referred to a specialized laboratory in Mexico City from January 2016 to April 2018. A descriptive analysis, and an age/food-group comparison were made. RESULTS: A total of 2633 subjects tested for food allergy were identified during the study period; 1795 subjects fulfilled the inclusion criteria. The overall positivity (sIgE≥0.35kUA/L) to at least one food was 24%. The most frequently positive foods were hazelnut, apple, shrimp, peanut, egg white, egg yolk, peach, almond, tomato, bean, milk, strawberry, kiwi, maize and wheat. Positivity for some foods was more frequent across different age groups, in young children (≤5 years) milk; in older children (6-17 years): peanut, almond, wheat, soy and maize; in adults: apple. We also found other foods with high positivity but less than 50 samples: rye 60%, mango 42.9%, carrot 37.5%, cashew 27.3%, banana 21.1% and oat 20.6%. CONCLUSION: Our study reported the presence of a differential regional IgE sensitization pattern as compared with the internationally reported one, highlighting the importance of local staple foods.

National clinical practice guidelines for allergen immunotherapy: An international assessment applying AGREE-II.

BACKGROUND: Since 1988, numerous allergen immunotherapy guidelines (AIT-GLs) have been developed by national and international organizations to guide physicians in AIT. Even so, AIT is still severely underused. OBJECTIVE: To evaluate AIT-GLs with AGREE-II, developed in 2010 by McMaster University methodologists to comprehensively evaluate GL quality. METHODS: Allergist, from different continents, knowledgeable in AIT and AGREE-II trained were selected into the project team. The project received methodologists' guidance. AIT-GLs in any language were sought from 1980 to 2016; AIT-GLs were AGREE II-evaluated by at least 2 team members, independently; discrepancies were resolved in a second round, by team discussion or methodologists' consulting. RESULTS: We found 31 AIT-GLs (15 post-2010), ranging from local consensus reports to international position papers (EAACI, AAAAI-ACAAI, WAO). Pre-2010 GLs scored 1.6-4.6 (23%-67%) and post-2010 GLs scored 2.1-6 (30%-86%), on a 7-point Likert scale. The highest scores went to: German-Austrian-Swiss (6.0), Mexican (5.1), and the AAAAI/ACAAI AIT-GL (4.7). These were also the only 3 GLs that received "yes" of both evaluators to the item: "I would recommend this GL for use." The domains of "Stakeholder involvement" and "Rigor of Development" only scored 3/7, and "Applicability" scored the lowest. Strikingly, newer GLs only scored clearly better in "Editorial independence" and "Global evaluation." CONCLUSIONS: In AIT-GLs, there is still a lot of room for improvement, especially in domains crucial for the dissemination. For some GLs, the "Scientific rigor" domain flawed. When resources are limited, transculturizing a high-quality GL might be preferable over developing a GL from zero. Our study and AGREE-II could help to select the best candidate. CLINICAL IMPLICATIONS: We here evaluate allergen immunotherapy guideline (AIT-GL) quality. Only high-quality AIT-GLs should be consulted for AIT management decisions. In low-resource settings, transculturization of these is preferred over developing low-quality guidelines.

Recommendations for the prevention and diagnosis of asthma in children: Evidence from international guidelines adapted for Mexico.

BACKGROUND: With the availability of high-quality asthma guidelines worldwide, one possible approach of developing a valid guideline, without re-working the evidence, already analysed by major guidelines, is the ADAPTE approach, as was used for the development of National Guidelines on asthma. METHODS: The guidelines development group (GDG) covered a broad range of experts from medical specialities, primary care physicians and methodologists. The core group of the GDG searched the literature for asthma guidelines 2005 onward, and analysed the 11 best guidelines with AGREE-II to select three mother guidelines. Key clinical questions were formulated covering each step of the asthma management. RESULTS: The selected mother guidelines are British Thoracic Society (BTS), GINA and GEMA 2015. Responses to the questions were formulated according to the evidence in the mother guidelines. Recommendations or suggestions were made for asthma treatment in Mexico by the core group, and adjusted during several rounds of a Delphi process, taking into account: 1. Evidence; 2. Safety; 3. Cost; 4. Patient preference - all these set against the background of the local reality. Here the detailed analysis of the evidence present in BTS/GINA/GEMA sections on prevention and diagnosis in paediatric asthma are presented for three age-groups: children with asthma ≤5 years, 6-11 years and ≥12 years. CONCLUSIONS: For the prevention and diagnosis sections, applying the AGREE-II method is useful to develop a scientifically-sustained document, adjusted to the local reality per country, as is the Mexican Guideline on Asthma.

Similar biological activity in skin prick test for Oralair® (8200 BAU) and Grazax® (6200 BAU) reinforces effective SLIT dosing level.

In Europe, allergen extracts are standardized based on skin prick wheal size in 20-30 allergic subjects. To understand the biological activity of clinically effective Sublingual immunotherapy, we used this method to determine the biological activity of solution and tablet Timothy grass pollen (TIM) extracts, compared to an FDA-approved extract (Reference) of 10 000 BAU/ml. Blinded, quadruplicate skin prick tests with concentrate and three serial half-log dilutions allowed the construction of a semilogarithmic regression line per extract. Bioequivalent allergy units (BAU) values were obtained from the comparison with reference. Extracts and dilutions showed a neat linear dose response (all: R2 > 0.98) in 33 rhinitis patients. Relative potencies: Staloral® 12 000 BAU/ml, Soluprick® 10 300 BAU/ml, Oralair® 8200 BAU, and Grazax® 6200 BAU. Even though all extract concentrates differed in wheal size (P = 0.01-0.001), Grazax® producing a 25% smaller wheal size than Oralair® , and the biological activity of these clinically effective TIM tablets led in the same range (6200-8200 BAU; 0.92-1.23 cm2 ). SLIT dose-finding studies for other pollens might start with allergen extracts producing 1.1 cm2 wheal surface.

Real life study of three years omalizumab in patients with difficult-to-control asthma.

BACKGROUND: Even though there are multiple options for the treatment of asthma, there still exists a fair group of patients with difficult-to-control asthma. We describe for the first time the real-world effects of three-year omalizumab treatment on patients with difficult-to-control asthma, seen in a social security hospital in a Latin American country. METHODS: Difficult-to-control asthmatic patients from the out-patient clinic of a regional hospital were recruited to receive a three-year omalizumab course. Efficacy parameters were asthma control test (ACT) score; FEV1; daily beclomethasone maintenance dose; and unplanned visits for asthma exacerbations (emergency room (ER), hospitalisations, intensive care). RESULTS: 52 patients were recruited, 47 completed the three-year treatment (42 female, 15-67 years, mean age 43.5). Comparing efficacy parameters of the year before omalizumab with the 3rd year of omalizumab: mean ACT improved from 12.4 to 20.5, mean FEV1 from 66.3% (standard deviation (SD) 19.1%) to 88.4% (SD 16.2%) of predicted, while mean beclomethasone dose reduced from 1750 to 766 mcg/day and there was a significant reduction in patients experiencing ER visits (from 95% to 19%, p<0.0001), hospitalisation (38% to 2%, p<0.0001) and intensive care (4% to 0, NS). Five patients discontinued omalizumab, two because of an adverse event (anaphylaxis, severe headache, both resolved without sequelae). CONCLUSION: Omalizumab improved most clinical parameters of Mexican patients with difficult-to-control asthma. Especially the rates of ER visits and hospitalisation were significantly reduced, thus reducing costs. Omalizumab was generally well tolerated.

Patterns of skin prick test positivity in allergic patients: usefulness of a nationwide SPT chart review.

BACKGROUND: A previous survey on allergens used by Mexican allergists in their skin prick test (SPT) panel showed wide variation. Humidity varies in different zones of Mexico. This might lead to differences in natural exposure and allergic sensitisation throughout the country. We aim to describe the SPT sensitivity patterns in the different climatic zones in Mexico and to show the usefulness of a structured SPT chart-review including multiple clinics in obtaining these allergen sensitisation patterns. METHODS: A retrospective, structured chart-review of SPT results was undertaken in allergy clinics throughout Mexico. Ratios of SPT positivity were calculated for individual allergens, per climatic zone and nation-wide. Per allergen group the most important allergens were identified. Statistically significant differences between zones and the nation-wide data were tested with Pearson's Chi-squares test. RESULTS: 4169 skin test charts were recollected. The most important allergens causing sensitisation were very similar in different zones, despite climate variation. The allergen with highest ratio of SPT positivity was Dermatophagoides pteronyssinus (51%), with trees (Ash-27%, Alder-22%, Oak19%), and Bermuda grass (26%) as second and third. In the hot zones (humid and dry) Aspergillus was statistically significant more frequently than in more temperate zones. Cockroaches thrive in big cities and humid zones and Mesquite and Poplar in dry zones. Weeds are less important. CONCLUSION: Mexico has its own SPT sensitisation pattern, which is different from America and Europe. A structured chart-review of SPT results is able to show this and might be a tool for allergists in other countries.

A comparison of in vitro potency between European and Mexican allergen extracts and US (CBER/FDA) reference extracts.

BACKGROUND: The most important allergen manufacturers are based in Europe and in the US. In some countries local products are also sold. No comparison between European, US and local products has been made until now. AIM OF THE STUDY: To determine total protein content and total specific IgE binding capacity or major allergen content of diagnostic extracts from European, US and Mexican origins relative to the CBER/FDA reference extracts for Dermatophagoides pteronyssinus (Dpt), Bermuda grass and cat (10,000(B) AU/mL). METHODS: Diagnostic extracts were purchased from various manufacturers, blinded and shipped to the analysing laboratory, where the following assays were conducted: total protein concentration (Bradford), specific IgE competition ELISA (Dpt and Bermuda grass) and determination of Fel d 1 U/mL. When available, CBER/FDA recommended tests and reagents were used. RESULTS: Total protein content of US reference extracts was higher than all other extracts. Relative potency of European and US-bought Dpt extracts 3,300-4,400 AU/mL, Bermuda grass 800-2,500 BAU/mL and cat 2.1-4.4 Fel d IU/mL (Ref. 19 U/mL), with one exception. Locally produced Mexican products were almost all below 1,000 (B)AU/mL. CONCLUSIONS: Three diagnostic extracts from European manufacturers and from Mexican providers which obtain extracts in US have a <50% relative potency compared to 10,000 (B)AU/mL US extracts. Locally produced Mexican extracts have much lower total protein content and specific IgE binding capacity. These in vitro results must be complemented with other in vitro and in vivo skin prick tests to obtain a more complete picture of comparison of potency. Nevertheless results are quite consistent for the allergens tested here.

Treacher-Collins syndrome and co-existing dermatomyositis.

BACKGROUND: Treacher-Collins syndrome, an autosomal dominantly inherited malformation of structures derived from the first and second branchial arch, has an incidence of 1:10,000 newborns. The prevalence of dermatomyositis at less than 24 years of age has been estimated at 1 per 100,000. The occurrence of both Treacher-Collins syndrome and dermatomyositis combined in the same patient should occur once in every 1,000,000,000 subjects. METHODS: We report a patient with Treacher-Collins syndrome who developed dermatomyositis at the age of 5 years. RESULTS: No other patient with both Treacher-Collins syndrome and an autoimmune disease has been reported. The thymus originates from the third branchial pouch and is unaffected by the syndrome. In Treacher-Collins syndrome the affected gene has been mapped to the fifth chromosome, while dermatomyositis is related to HLA B8 and DR3, coded on the sixth chromosome. No immunologic alteration has been described in patients with Treacher-Collins syndrome. CONCLUSION: This is the first report of a patient with Treacher-Collins syndrome and dermatomyositis. There is no genetic or physiopathologic explanation for the concurrence of both conditions.