Indoor Allergens Assessing and Controlling Adverse Health Effects (1993) / Chapter Skim
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2 Magnitude and Dimensions of Sensitization and Disease Caused by Indoor Allergens
2 Magnitude and Dimensions of Sensitization and Disease Caused by Indoor Allergens
Pages 44-85
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From page 44... ...
For example, the observation that allergy often develops by age 5 suggests that interventions are needed for infants and young children. Incidence and prevalence rates can be determined for the entire population, or they can be specified by gender, age, ethnic group, socioeconomic class, geographical region, or time of year.
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From page 45... ...
rates for specific age ranges Comparison of the probability of developing asthma among people with and without skin test reactivity Attributable fraction Attributable fraction Generally speaking, mild disease causes symptoms but only intermittently requires medication and infrequently alters life activities. Moderately severe disease may require regular physician visits, regular medication, and lost time from work or school.
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From page 46... ...
antibody against one or more common allergens. The presence of skin test reactivity indicates an increased risk for one of several diseases including allergic rhinitis and asthma, but at the time skin test reactivity is detected, disease may or may not be present.
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From page 47... ...
Prevalence rates of sensitization also increase somewhat with the use of a greater number of allergens during testing (Barbee et al., 1987~. Table 2-3 and Figure 2-3 show estimates of the prevalence of sensitization in certain population samples to specific allergens as determined by skin test reactivity.
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From page 49... ...
49 cdo~ a: 3 u: 0 a' Cal C)
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From page 50... ...
Infants of parents with allergic disease develop positive skin tests at higher rates than infants in population-based studies. Skin prick test reactivity during the first year of life has been reported as ranging between 30 and 70 percent of at-risk infants-i.e., those who have one or both parents with allergic disease (Zeiger, 1988~.
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From page 51... ...
51 o o v: o o · cd o to to At - ~ o · At .
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From page 52... ...
. Exposure to environmental tobacco smoke is another example of an environmental risk factor in that it appears to be associated with increased skin test reactivity in children (Burrows and Martinez, 1989)
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From page 53... ...
found lower rates of skin test reactivity among current smokers than either nonsmokers or ex-smokers; ax-smokers had higher rates of skin test reactivity than nonsmokers. The study team interpreted this finding as demonstrating a self-selection process; that is, smokers with skin test reactivity would stop smoking.
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From page 54... ...
Ispaghula, psyllium Wood dust (western red cedar, oak, mahogany, zebrawood, redwood, Lebanon cedar, African maple, eastern white cedar) Colophony (pine resin)
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From page 55... ...
Allergic Rhinitis Sinusitis Asthma Allergic Dermatitis :: Allergic Broncho- pulmonary Aspergillosis Hypersensitivity Pneumonitis 0 10 20 Prevalence (°/0) FIGURE 2-4 Estimated range of prevalence of diseases in total U.S.
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From page 56... ...
* The data on aeroallergen exposure, which were derived from Sporik and colleagues, were obtained from a cohort of newborns, each of whom had one parent with allergic disease.
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From page 57... ...
The diagnosis is based on one or more of the following: history of episodic symptoms, signs of asthma on physical examination (chiefly wheezing) , or pulmonary function test results demonstrating reversible airflow obstruction and bronchial hyperreactivity (see Chapter 51.
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From page 58... ...
Diagnostic criteria may be influenced by the local language, customs, and definitions and by physician habits, questionnaires, and study objectives (Kryzanowski et al., 1990~. Examples of the epidemiologic definition of asthma include a history of episodic or persistent wheezing, a physician diagnosis of asthma, evidence of reversible airflow obstruction on pulmonary function tests, evidence of bronchial hyperreactivity, or a combi
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From page 59... ...
Another problem with calculating attributable fractions is the issue of competing risks. Individuals may be exposed simultaneously to several risk factors, such as house dust mite, cockroach, and cat allergens.
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From page 60... ...
, also called the population attributable risk, is the proportion of the disease that can be attributed to exposure to the risk factor; Ip is the incidence in the population; and Iu is the incidence in the unexposed population. The attributable fraction in the exposed population is calculated as: AF _ Ie-IU e- Ie where AFe is the attributable fraction (exposed)
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From page 61... ...
Trends Over Time Figures 2-7, 2-8, and 2-9 show recent trends over time in asthma prevalence, mortality, and hospitalization rates, respectively. The prevalence rate of asthma in the first half of the century was about 1-2 percent in Caucasian populations in industrialized countries (Gregg, 1989~.
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From page 64... ...
Over the past 20 years, much higher current and cumulative prevalence rates have been reported from surveys of both children and adults; Figure 2-7 shows the rise in rates for 1980-1987 alone. Mortality epidemics occurred in Britain and Australasia around 1960 and in Britain and New Zealand in the 1970s.
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From page 65... ...
The increase in death rates has been seen across ages and races but is particularly notable among African Americans (NHLBI, 1 99 1; Sly, 1 988~. Increases in asthma mortality have been variously attributed to inadequate medical management (especially among minority patients of low socioeconomic status)
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From page 66... ...
age-adjusted death rates, 19791987. Source: NHLBI, 1991.
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From page 67... ...
This relationship has been shown using a variety of definitions of asthma and different study designs. New asthma that develops before age 40 is likely to be associated with allergen skin test reactivity, high total serum IgE, a family history of atopy, and prior symptomatology.
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From page 68... ...
provided evidence that exposure to the aeroallergen Alternaria is a risk factor for sudden respiratory arrest in asthmatics. The O'Hallaren team found that alternaria skin test reactivity was associated with a 200-fold risk of respiratory arrest, the tim ing of which corresponded uniformly with the alternaria season in that region.
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From page 69... ...
. This suggests that similarities in urban and rural asthma prevalence rates may mask significant differences in relevant allergen exposures and sensitivities.
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From page 70... ...
Between 1979 and 1984, the mortality rate rose from 1.8 to 2.5 per 100,000 population among African Americans and from 1.1 to 1.4 per 100,000 among Caucasians. Socioeconomic Status Socioeconomic status seems to contribute significantly to asthma prevalence rates and to indices of disease severity.
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From page 71... ...
Absenteeism and other impacts have not been adequately assessed. Risk Factors Allergy A high degree of skin test reactivity to common allergens correlates well with the rate of allergic rhinitis in population studies (Bur
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From page 72... ...
In a study conducted in Tucson, allergic rhinitis was similar whether skin test reactivity was positive for perennial allergens (such as house dust mites) or seasonal allergens.
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From page 73... ...
. Risk Factors The prevalence of eczema was not related to skin test reactivity in one population-based study (Burrows et al., 1976)
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From page 74... ...
Most of the allergens associated with contact dermatitis are not aeroallergens; however, there have been instances in which airborne contact allergens have produced contact dermatitis. Less Common Diseases Clearly Related to Allergy Allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and humidifier fever are conditions that appear to be less common in the United States than the diseases discussed previously in this chapter.
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From page 75... ...
Table 2-7 lists various causes of hypersensitivity pneumonitis that have been reported in nonindustrial indoor environments. Prevalence No prevalence rates are available for the general population.
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From page 77... ...
occurs infrequently. However, lifeguards at an indoor swimming pool reportedly experienced an extremely high rate of attack of a hypersensitivity pneumonitis-like condition; the causative agent of the disease remains unidentified (Rose and King, 19924.
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From page 78... ...
These include chronic sinusitis and bronchitis, sick building syndrome and other nonspecific syndromes, and acute respiratory illnesses. SINUSITIS Sinusitis is defined as inflammation of the sinuses, which are four pairs of hollow structures that surround the nasal cavity.
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From page 79... ...
, did not show a relationship between reported sinusitis and skin test reactivity. Nonallergic factors that predispose an individual to sinusitis are upper respiratory infection, overuse of topical decongestants, hypertrophied adenoids, deviated nasal septum, nasal polyps, nasal tumors, foreign bodies, cigarette smoke, swimming and diving, barotrauma, and dental extractions.
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From page 80... ...
Patients in subset 3 have chronic productive cough with airways obstruction but no emphysema; it is not known how large this subset is, since data from epidemiologic studies using the computer tomography scan, the most sensitive in vivo imaging technique for diagnosing or excluding emphysema, are not available. It is much easier to identify in the chest radiography patients with emphysema who do not have chronic bronchitis (subset 41.
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From page 81... ...
The index rises with the number of positive skin tests and the magnitude of the skin test reaction to each allergen. Therefore, an individual with many strongly positive skin tests to many allergens is much more likely to show bronchial hyperresponsiveness than an individual with no skin test reactivity.
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From page 82... ...
, and infection with Legionella species are included in this category of illness. Prevalence rates for specific syndromes are largely unknown and estimates vary tremendously among buildings.
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From page 83... ...
Data on its exact magnitude and dimensions, however, are incomplete, or lacking, in many cases. Better data regarding the incidence, prevalence, attributable fraction, and cost of allergic diseases are essential to the development of effective programs of prevention and control.
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From page 84... ...
Research Agenda Item: Determine prevalence rates of sensitization, allergic diseases, and respiratory morbidity caused by regionally and locally relevant indoor allergens and assess the contributions of different allergens to these conditions. Socioeconomic status seems to contribute to asthma prevalence rates and to indices of disease severity.
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From page 85... ...
Research Agenda Item: Encourage and conduct additional research to identify and characterize indoor allergens. The new information should be used to advise patients about avoiding specific allergenic agents.
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