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Wise et al.

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later, the National Health and Nutrition Examination Survey (NHANES) 1976–1980 was conducted among a geographically representative sample of the U.S. population. This survey gave broadly similar estimates for prevalence of AR, defined as “physician diagnosis of hay fever or frequent nasal and/or eye symptoms that varied by both season and pollen during the last 12 months, not counting colds or the flu.” 453 A more recent report based on NHANES (2005-2006), presented population prevalence figures in which two-thirds were over the age of 20 years, and showed the lifetime prevalence of physician-diagnosed hay fever was 11.3%, with 6.6% having symptoms in the last 12 months. However, reliance on physician diagnosis of AR is likely to considerably under-estimate the actual prevalence of AR, since many patients self-diagnose and self-treat. Surveys involving patient self reporting AR have shown that one-third of the population reported “sneezing and/or nasal symptoms in the absence of cold or a flu,” with about 24% reporting that this was seasonal in nature, and a further 10% reporting these symptoms occurred year-round (ie, perennial). 454 In the early 1990s, the European Community Respiratory Health Survey (ECRHS), a multicenter population-based study of adults age 20 to 44 years in 23 countries (mainly Western Europe, but also Australia and New Zealand), used a self-completed questionnaire to estimate the prevalence of “hay fever or nasal allergies.” Prevalence varied between 10% and 40% across participating centers, 455 with even more participants (12-65%) reporting that they experienced a runny or stuffy nose or started to sneeze on exposure to sources of allergen. 456 If a positive SPT was included in the disease definition, the prevalence of AR fell by a variable amount (absolute fall in prevalence between 4% and 16% across all centers). In the Swiss Study of Air Pollution and Lung Disease in Adults (SAPALDIA), conducted around the same time as the ECRHS, the prevalence of self-reported “nasal allergies including hay fever” in adults aged 18 to 60 years was 17.9%, and the prevalence of current symptoms (“hay fever this year or last year”) was 14.2%. 457 Prevalence estimates were lower if a positive SPT was included (11.2% for current hay fever with at least 1 positive SPT and 9.1% for current hay fever with positive SPT to 1 of grass, birch, or Parietaria ). More recently, the Global Allergy and Asthma Network of Excellence (GA 2 LEN) study suggested the prevalence of “nasal allergies and hay fever” varied between 22% and 41% in adults age 18 to 75 years living in the 12 participating European nations. 458 Population-based studies have shown increases in AR prevalence in the adult population in recent decades. For example, in Renfrew Paisley, UK, the prevalence of hay fever was higher in adults and children in 1996 than in their mothers and fathers at an equivalent age in 1972. 459 Hay fever prevalence doubled between 1981 and 1990 in Busselton, Australia, 460 increased in Italy from 1991 to 2010, 461 and increased in 8 of 11 cities in China surveyed in 2005 and again in 2011. 462 In Uppsala, Umea, and Goteborg, in Sweden, “hay fever and nasal allergies” increased from 21% to 31% between 1990 and 2008, 463 although recent reports from Stockholm suggest there may be a leveling off in the increase in nasal allergies over more recent years. 464

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From these data, the lifetime prevalence of AR in the United States can be estimated between 11% (physician-diagnosed) and approximately 33% (self-reported). In Europe,

Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.