Bias in retrospective studies of trends in asthma incidence.

Gulsvik A.

Dept of Thoracic Medicine, Institute of Medicine, University of Bergen, Bergen, Norway. jan.brogger med.uib.no

There is evidence for an increase in adult asthma prevalence. Several retrospective studies have shown an increase in asthma incidence by year of birth, consistent with an increasing trend in asthma incidence. The validity of this retrospective approach is unknown. Retrospective and prospective asthma incidence by year of birth were compared in the same community, during the same time period, from two independent studies; a cohort study and a cross-sectional study in Western Norway. In the prospective study, subjects without asthma were followed from 1985-1996/1997. In the retrospective study in 1998, subjects reported the age at which the disease started. Analyses of incident asthma in the period 1985-1996 were compared between the studies. The retrospective analysis showed a large increase in asthma incidence by year of birth, with an odds ratio (OR) of 2.9 comparing those born in 1969 with those born in 1927. The prospective study showed the opposite, with an OR of 0.2 comparing those born in 1969 with those born in 1927. There was only a 20% difference in the cumulative incidence of asthma. To conclude, retrospective estimates of trends in asthma incidence are likely to be severely biased by differential recall.

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Relationship between quality of life and clinical status in asthma: a factor analysis.

O'Byrne PM.

Dept of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. juniper qoltech.co.uk

Many studies have shown that correlation between clinical asthma status and asthma-specific quality of life is only weak to moderate. However, this relationship has never been explored to determine whether the weakness is due to noise of measurement or whether quality of life is a distinct component of asthma health status. With a database from three clinical trials (n = 763), factor analysis was used to explore the relationships between quality of life, measured by the Asthma Quality of Life Questionnaire (AQLQ), and conventional measures of asthma clinical status (symptoms, airway calibre and rescue beta2-agonist use). The analysis revealed that although patients with severe, poorly controlled asthma tend to have worse quality of life than milder, well-controlled patients, overall asthma health status has four components (factors): asthma-specific quality of life; airway calibre; daytime symptoms and daytime beta2-agonist use, and night-time symptoms and night-time beta2-agonist use. The clean loading of all 21 outcomes onto four distinct and clinically identifiable factors suggests that, although some weakness of correlation between clinical indices and quality of life may be due to noise of measurement, it is mainly attributable to asthma health status being composed of distinct components.

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Relationship of self-reported asthma severity and urgent health care utilization to psychological sequelae of the September 11, 2001 terrorist attacks on the World Trade Center among New York City area residents.

Vlahov D.

Center for Urban Epidemiologic Studies, New York Academy of Medicine, 1216 Fifth Avenue, New York City, NY 10029-5283, USA.

OBJECTIVE: Posttraumatic psychological stress may be associated with increases in somatic illness, including asthma, but the impact of the psychological sequelae of the September 11, 2001 terrorist attacks on physical illness has not been well documented. The authors assessed the relationship between the psychological sequelae of the attacks and asthma symptom severity and the utilization of urgent health care services for asthma since September 11. MATERIALS AND METHODS: The authors performed a random digit dial telephone survey of adults in the New York City (NYC) metropolitan area 6 to 9 months after September 11, 2001. Two thousand seven hundred fifty-five demographically representative adults including 364 asthmatics were recruited. The authors assessed self-reported asthma symptom severity, emergency room (ER) visits, and unscheduled physician office visits for asthma since September 11. RESULTS: After adjustment for asthma measures before September 11, demographics, and event exposure in multivariate models posttraumatic stress disorder (PTSD) were a significant predictor of self-reported moderate-to-severe asthma symptoms (OR = 3.4; CI = 1.2-9.4), seeking care for asthma at an ER since September 11 (OR = 6.6; CI = 1.6-28.0), and unscheduled physician visits for asthma since September 11 (OR = 3.6; CI = 1.1-11.5). The number of PTSD symptoms was also significantly related to moderate-to-severe asthma symptoms and unscheduled physician visits since September 11. Neither a panic attack on September 11 nor depression since September 11 was an independent predictor of asthma severity or utilization in multivariate models after September 11. CONCLUSIONS: PTSD related to the September 11 terrorist attacks contributed to symptom severity and the utilization of urgent health care services among asthmatics in the NYC metropolitan area.

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[Risk factors, clinical and laboratory aspects of asthma in children]

[Article in Portuguese]

Assami NM.

Universidade Federal do Mato Grosso, Cuiaba, MT, Brazil.

OBJECTIVE: To evaluate the clinical and laboratory aspects and the risk factors associated with asthma in children treated at the Pediatric Outpatient Clinic of Hospital Universitario Julio Muller. METHODS: A case-control study including 59 asthmatic children (cases) and 104 nonasthmatic children (controls). The following factors were considered for risk analysis: parents level of education, domestic exposure to allergens, passive smoking, breast feeding, low income, and family history of allergy. Samples of blood were collected for hemogram and to determine the total serum IgE as well as the one specific to allergens. Immediate hypersensitivity skin tests were performed with puncture for the detection of the following allergens: house dust mite, animals, molds, and cockroaches with positive (histamine) and negative controls (physiologic solution). A logistic regression model was used to calculate the odds ratio (OR) and 95% confidence intervals (95%CI) adjusted for risk factors and for confounding factors. RESULTS: Among the risk factors studied, sex, parents low level of education, low income, length of the breast feeding period, and passive smoking were not associated with the presence of asthma. The domestic exposure to allergens was similar in both groups except for the higher frequency of pets at the homes of control patients (chi-square=16.9; P<0.05). Paternal history of rhinitis was the only association with asthma (OR=3.33; 95%CI: 1.03-11.17; P<0.05). The asthmatic children presented higher frequency of positive reactions to skin tests than the controls, mainly to house dust mites: Dermatophagoides pteronyssinus (69.5%), Dermatophagoides farinae (59.3%) and Blomia tropicalis (59.3%); cockroaches: Periplaneta americana (59.3%), and cat: Felis domesticus (37.3%), with OR between 11.2-21.0; P<0.05. Eosinophilia and serum levels of total IgE were more elevated in the group of asthmatic children (P<0.05). The positivity of the specific IgE test for Dermatophagoides pteronyssinus and Blomia tropicalis was higher in the cases than in the controls (P<0.05). The multivariate analysis showed that sensitization to the allergens produced by cockroaches (OR=9.26; 95%CI: 2.59-33.4), animals (OR=3.93; 95%CI: 1.05-14.67) and house dust mites (OR=3.74; 95%CI: 1.18-11.8) were the most important risk factors for asthma. CONCLUSIONS: The sensitization to indoor allergens, mainly to house dust mites, cockroaches, and cats showed a strong association with asthma in this study.

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The pattern of indoor and outdoor respiratory allergens in asthmatic adult patients in a humid and desert newly developed country.

Bener A.

BACKGROUND: Studies have shown that allergens are very important sensitizing agents in patients with asthma. Respiratory disorders such as asthma and allergic rhinitis are common in the State of Qatar. OBJECTIVE: To characterize the most frequent indoor and outdoor respiratory allergens involved in bronchial asthma and allergic rhinitis in the State of Qatar. DESIGN: A hospital-based prospective study conducted. SETTING: Allergy Laboratory at the Hamad General Hospital and Hamad Medical Corporation, Doha, State of Qatar. PATIENTS: Adult patients over 12 years of age diagnosed with bronchial asthma and/or allergic rhinitis who were referred for allergy skin pick test. 1106 adult patients recruited with respiratory diseases of suspected allergic origin who attended Allergy Clinic at the Hamad General Hospital, during three years from January 2001 to April 2003. Total of 1106 whom 607 were females (54.9%) and 499 were males (45.1%) and their mean was age 30 years (12-48). METHODS: Skin Prick Test [SPT] was performed on 1106 patients for common allergens whom The blood sample was taken for measuring specific IgE concentration. RESULTS: There were 1106 patients studied and 569 patients (51.4%) had positive skin prick test. All patients expressed clinical allergy, 464 patients (52%) had asthma and rhinitis, 286 patients (32%) had rhinitis alone and 137 patients (15%) had asthma alone. The population sample had a higher prevalence of diagnosed asthma among females (32.7%) than in males (29.8%) and also skin conditions such as eczema, pruritus, and urticaria higher in females (9.1%%) than males (7.0%). Similarly, males had higher prevalence of allergic rhinitis (86.0%) than in females. There were 318 (55.9%) patients whose asthma developed before they were 10 years old. The percentage of asthmatic patients with a positive family history of asthma was 44%. The most common allergens detected in order of frequency were Dermatophagoides Pteronyssimus (Der p l) in 248 patients (41.6%), Dermatophagoides Farinae (Der f l) in 220 patients (36.9%), Cockroach allergen (Bla g l) in 192 patients (32.2%). The study showed that females are more exposed to pollen, grasses and tress, but males are mostly exposed to mites and insects. Furthermore, Molds and Yeast were common among males. CONCLUSION: In conclusion, the frequency of indoor and outdoor allergens in state of Qatar, based on skin prick test study showed the dominance of house dust mites, pollen, grasses which are more or less same to other countries with similar and even with different climate. Reduced exposure to these agents will help control raising severity of these disease.

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How well do doctors know their patients with severe asthma?

Victorian Asthma Mortality Study Group.

Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia. Michael.Abramson med.monash.edu.au

BACKGROUND: Rates of asthma mortality have fallen in Australia since the commencement of the National Asthma Campaign and promotion of the Australian asthma management plan. New strategies are now needed to further reduce mortality. AIM: To examine agreement about key features between asthma patients and their general practitioners (GPs). METHODS: We interviewed: (i) the next of kin of 56 asthma deaths, (ii) 91 asthma patients presenting to emergency departments with acute severe asthma and (iii) 147 of their GPs. RESULTS: Agreement was substantial for usage of oral symptomatic medication, but poor for inhaled symptomatic and preventive medications. There was moderate agreement regarding hospital admissions within the last 12 months among the cases, but little about other markers of severity. There was moderate agreement where the presenting or fatal attack was triggered by an upper respiratory-tract infection or aspirin. The next of kin and GPs agreed about family problems, but not about other psychosocial issues. They also agreed about which cases had been given action plans or verbal instructions, but few other aspects of asthma management. There was also moderate agreement regarding the use of peak flow meters by the controls. CONCLUSIONS: Doctors often have relatively poor insights into self-management practices, social background or trigger factors, even in high-risk patients. This should be considered when planning future campaigns to improve asthma management and further reduce mortality.

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