An experience estimating food allergy prevalence in Mexican adults: going beyond self-report

To the Editor, We read with great interest the article by Morales-Romero et al. [1], which provides valuable data on the prevalence of adverse food reactions and food allergy (FA) among adults in western Mexico. Their finding that self-reported FA prevalence has remained stable over a decade is an important contribution in a country with limited epidemiological data on FA. The authors rightly acknowledge that survey-based studies may overestimate the prevalence of FA, highlighting the need for studies incorporating objective diagnostic criteria. In this context, we wish to share our experience from a population-based study on FA in northwestern Mexico, which highlights the challenge of estimating FA prevalence rates based on objective diagnostic criteria in our country. We conducted a 2-phase, cross-sectional study in a representative sample of adults (n = 834) from Culiacán, Sinaloa, using a validated questionnaire. Suspected cases of immediate-type FA were identified in phase 1, and skin prick tests (SPTs) were performed in phase 2 (the Research Ethics Committee of the Center for Research and Teaching in Health Sciences from the Autonomous University of Sinaloa approved the study, Registry No. 191-2025). Eighteen participants met the criteria to undergo SPTs (no medical diagnosis of FA, but suspected of it), but only 3 of them (16.7%) agreed to take the test, which hampered a statistically robust estimation of SPT-positive FA prevalence. Certainly, a positive SPT does not guarantee a clinical reaction to the suspected food, but a negative one has a high negative predictive value, allowing us to make estimates closer to the real prevalence than when only surveys are conducted. In fact, food sensitization was confirmed in 2 of the 3 cases tested in our study (Table 1). We speculate that the low response rate at follow-up for performing SPTs may stem from factors common in the research field, such as fear of medical procedures, logistical barriers for participants, or a general distrust, which are significant obstacles to consider [2]. Table 1. - Demographic characteristics and SPT results of participants with suspected FA Participant ID 010 Participant ID 014 Participant ID 018 Age (years) 25 26 21 Sex Female Female Male Positive control 8 mm 6 mm 6 mm Negative control 1 mm 1 mm 0 mm Raw fish 4 mm (+) Not evaluated Not evaluated Cooked fish 5 mm (+) Not evaluated Not evaluated Raw shrimp Not evaluated 0 mm (−) 6 mm (+) Cooked shrimp Not evaluated 1 mm (−) 7 mm (+) Tomato Not evaluated Not evaluated 2 mm (−) Results of 3 adults from Culiacán, Sinaloa, with suspected IgE-mediated FA without a prior medical diagnosis. Skin prick tests (SPTs) were performed using the prick-by-prick technique with fresh foods (raw and cooked). A positive control (histamine) and a negative control (saline solution) were included for each participant. The test was read after 15–20 minutes, and a result was considered positive (+) when the wheal diameter was ≥3 mm larger than the negative control. A negative result (−) was indicated by a wheal diameter