Given the potentially inaccurate inferences when extrapolating research findings from different countries, especially on allergic conditions where the “drivers” of risk may be substantially different and vary dramatically among regions of the same country [14], it is crucial to have national estimates of epidemiological trends in these conditions. This is particularly important in Latin America, where the diversity of environmental conditions is high [15]. Colombia is a country of over 41 million inhabitants, predominantly urban (72%), where about 30% live in the four largest cities (Bogota, Medellin, Cali and Barranquilla). Similar to other countries in the Andean region (Venezuela, Ecuador, Peru, Bolivia), Colombia is experimenting changes consistent with a society in transition, with an aging population, where the main causes for death are chronic diseases. Colombia´s GIP, life expectancy, mortality rates and other basic health indicators are closer to those of Peru and Ecuador [16].

For Colombia, while previous research on asthma and other allergic conditions can serve as a good base for comparisons [5,6,17]‐[19], there is limited information available for both adults and children simultaneously on the current burden and impact of allergic conditions. This is the case as well for many Latin American countries, and certainly for those in the Andean and Caribbean regions.

The current study used the same questions as the ISAAC initiative worldwide, and was conducted in the same cities in Colombia as a previous study from the same research group eleven years ago [17]. However, differences in age groups, methods and in data analysis, as well as in allergens used for sIgE, preclude a formal comparison between the two surveys, or with others conducted previously in Colombia and abroad. Thus, contrasts discussed here can only suggest potential tendencies over time. Our study suggests that the prevalence of symptoms of all three conditions is increasing in Colombia. This tendency towards an increase is similar to that found in ISAAC studies over an average of 8years in the region; for the 13–14 age group, Latin America was one of the few regions in the world (with Africa) that had more centres increasing prevalence of all three diseases simultaneously [4]. The wide variations observed in this study in the prevalence of the three conditions, as well as those observed between cities and for the different age groups, have been found previously elsewhere [24], as well as for Latin American countries [25]. These differences suggest that local factors may dramatically alter the prevalence of these conditions, and they can include a wide number of both genetic and environmental characteristics acting simultaneously and synergistically. The study by Mallol et al [25] that included three cities in Colombia (Bogota, Cali, Barranquilla), did not find a positive associations between asthma and the socioeconomic variables studied (latitude, altitude, national gross income, poverty). The Isaac III study in Bogota, however, found that asthma symptoms were correlated with the presence of a cat in the home, higher maternal education, watching televison 1 to 2 hours per day, and the use of acetaminophen and antibiotics in the last year [18]. In that same study, rhinoconjunctivitis symptoms were associated with previous acetaminophen and antibiotic use, and higher maternal education and cesarean birth [26]. Additional risk factors in Latin America have also been postulated and described in detail by Cooper et al elsewhere [27,28].

The prevalence of current asthma symptoms (12%) seems to have increased in Colombia with respect to results obtained 11years ago (10%) [16]. The age group where asthma symptoms where most frequent in both surveys is the 1–4year old group. It is likely that some of these symptoms correspond to wheezing episodes associated with respiratory viral infections early in life [29]; recent evidence, however, also suggest that bronchial obstruction during acute respiratory infection in childhood is clearly associated with subsequent asthma, especially among school-aged children at risk for repeated asthma exacerbations [30], making it relevant to quantify and to include in epidemiological studies. In the current survey we found an increase in current asthma symptoms for those subjects 5–17years of age. In the ISAAC I-III 13–14 age group, similar increases were found in Latin America for Mexico, Costa Rica, Panama, Chile, and Argentina [4].

Disease severity for asthma remains high when compared with results 11years ago. This may be due to under-diagnosis of asthma; in both surveys, the frequency of physician diagnosis is very low when compared to symptom-based prevalence, especially for subjects below age 18years of age, suggesting limited access to specialized health care in these age groups. Suboptimal asthma control can be another explanation for persistent disease severity, due to lack of general physician awareness on current guidelines on effective treatment strategies for asthma [31,32]. Disease burden to the patient and the caregiver was important in our study, with more of 60% of asthma patients reporting out-of-pocket expenses. Inappropriate ambulatory care of subjects with asthma can also be associated with increased hospitalization due to exacerbations; asthma is an ambulatory care sensitive condition where the need for hospitalization can be a marker of inappropriate health care [33]. Additionally, the mean number of days lost from work or school is our study is consistent with moderate persistent asthma, a stage of severity associated with substantial health care costs and hospitalizations in previous studies in the literature [34,35].

While the presence of asthma independent of increased IgE levels is not uncommon [36], the majority (60%) of subjects with asthma symptoms in the past year met the criteria for atopy in our study. This is lower than the frequency obtained in the previous study in 1999 (76%), but still high. The frequency of atopy may vary between regions and countries, which is expected because it depends on environmental and genetic factors [37]. There were statistically significant differences in atopy between cases and a control group in our study. In our population, the high frequency of atopy among controls may be explained in part because of exposure to helminths, mainly Ascaris lumbricoides infections, early in life [38]. Nematode exposure induces specific IgE responses and increases total IgE levels. In the tropics, permanent exposure to mite allergens and parasite infections during childhood may induce sIgE to cross-reacting allergens from mites and Ascaris[39,40].

The prevalence of AR symptoms also seems to have increased with respect to the previous study (from 23% to 32%) [17], but with a modest increase compared to a more recent survey in three Colombian cities that used the same ISAAC methodology during 2002 [41]. The larger increase in AR symptoms (than that seen for asthma symptoms) is in line with the ISAAC I-III comparisons in Latin America, where more centres had an increase for AR than for asthma [4]. With 28% current prevalence of rhinoconjunctivitis in children 5–17years old (data not shown), Colombia would be among the countries in the region with the largest prevalence, as detected by ISAAC methodology [4,6,41]. Similarly, the prevalence of AE symptoms (14%) increased markedly in comparison to results obtained 11years ago (4%). The current prevalence of AE symptoms has increased as well when compared with results obtained for Colombia during 2002 in the 6–7 and 13–14year old population [5].