Exhaled nitric oxide in contrasting population samples of Finnish and Russian Karelia

Abstract

To the Editors: Considerable differences between countries in prevalence of asthma and atopy have been reported that show association between increased risk and western lifestyle and urbanisation 1. The allergy substudy of the National FINRISK Study and the Karelia Allergy Study, both carried out in North Karelia, Finland, and the Pitkaranta region, Russia, revealed a significantly higher occurrence of asthma and atopic diseases on the Finnish side, the disparity showing a growing generational trend 2, 3. Despite the geographical neighbourhood, the sensitisation rates for airborne allergens, determined with skin-prick tests or specific immunoglobulin (Ig)E levels, were four-fold in children and two- to three-fold in adults from Finnish Karelia, which may be attributed to the higher level of urbanisation, western type of living conditions and poor microbial environment 4. Exhaled nitric oxide (eNO) is a noninvasive marker of airway inflammation, and is usually increased in patients with asthma. eNO is strongly associated with atopy in population-based studies 5–9. Also, many other factors, such as sex and anthropometric dimensions, tobacco smoking and acute respiratory infections, have been reported to influence eNO levels. To date, there are no reports of the differences in eNO levels between populations with different degrees of urbanisation and living conditions. We postulated that different atopic prevalences between Finnish and Russian Karelia might be reflected in the levels as well as the determinants of eNO. Therefore, in the Karelia Allergy follow-up study in 2007, we measured eNO levels in adult population samples from Finnish and Russian Karelia, and investigated the effect of several demographic, disease-related and environmental factors. Random samples of adults aged 25–54 yrs were drawn from the population register and electoral rolls in Finnish and Russian Karelia, with …