Publications

BACKGROUND

Perceived control of certain chronic conditions influences health status outcomes.

OBJECTIVE

To explore the impact of perceived control of asthma on asthma-specific and generic health status outcomes among adults with asthma. Perceived control was defined as individuals' perceptions of their ability to deal with asthma and its exacerbations.

METHODS

Data were drawn from the baseline and first two followups of a longitudinal study of adults with asthma surveyed by telephone at 18-month intervals. An 11-item questionnaire (Perceived Control of Asthma Questionnaire [PCAQ]) was developed and validated.

RESULTS

The PCAQ demonstrated high internal consistency (Cronbach's alpha = 0.79). Greater perceived control was associated with less severe asthma, greater asthma self-efficacy, lower perceived asthma severity, lower perceived danger from asthma, and greater perceived usefulness of asthma medicines. Greater perceived control was significantly associated with better asthma-specific quality of life concurrently and 18 and 36 months later, after controlling for demographics, smoking, and severity of asthma. Greater perceived control as also significantly associated with generic mental health outcomes concurrently and 18 and 36 months later, after controlling for covariates. Perceived control was associated with physical function concurrently and 18 months later, but not 36 months later.

CONCLUSIONS

The PCAQ is a reliable and valid measure of perceived control of asthma. Perceived control of asthma was associated with both asthma-specific and generic health status outcomes, concurrently and predictively. If perceived control could be modified, better outcomes, particularly better psychologic outcomes, might be achieved for individuals with asthma.

OBJECTIVES

In California, state law now prohibits smoking in most public places. We examined the prevalence and short-term health impact of environmental tobacco smoke (ETS) exposure during travel among adults with asthma.

DESIGN, SETTING, AND PARTICIPANTS

A cohort of 374 nonsmoking adults with asthma recruited from a random sample of allergy, pulmonary, and family practice physicians in northern California underwent structured telephone interviews.

MEASUREMENTS AND RESULTS

The prevalence of self-reported ETS exposure during travel in the past 12 months was substantial (30%; 95% confidence interval, 25 to 35%). Of the exposed subjects, approximately one third (34%) indicated no other regular source of ETS exposure. ETS-related cough, wheezing, or chest tightness during travel was the most common complaint (66%), followed by eye irritation (46%) and nose irritation (43%). After ETS exposure, many subjects indicated extra inhaled asthma medication use (55%). Subjects with no other regular ETS exposure reported a greater likelihood of eye irritation (58% vs 40%; p = 0.068) and nose irritation (58% vs 36%; p = 0.025) than persons with regular exposure. In contrast, there were no differences in respiratory symptoms, asthma medication use, or asthma exacerbation by regular ETS exposure status.

CONCLUSIONS

In adults with asthma, ETS exposure is common during travel. For many subjects, travel is their principal source of exposure.

BACKGROUND

Because they have chronic airway inflammation, adults with asthma may be particularly susceptible to indoor air pollution. Despite widespread exposure to environmental tobacco smoke (ETS), gas stoves, and woodsmoke, the impact of these exposures on adult asthma has not been well characterised.

METHODS

Data were used from a prospective cohort study of 349 adults with asthma who underwent structured telephone interviews at baseline and 18 month follow up. The prospective impact of ETS, gas stove, and woodsmoke exposure on health outcomes was examined.

RESULTS

ETS exposure at baseline interview was associated with impaired health status at longitudinal follow up. Compared with respondents with no baseline self-reported exposure to ETS, higher level exposure (>/=7 hours/week) was associated with worse severity of asthma scores at follow up, controlling for baseline asthma severity, age, sex, race, income, and educational attainment (mean score increment 1.5 points; 95% CI 0.4 to 2.6). Higher level baseline exposure to ETS was also related to poorer physical health status (mean decrement -4.9 points; 95% CI -8.4 to -1.3) and asthma specific quality of life (mean increase 4.4 points; 95% CI -0.2 to 9.0) at longitudinal follow up. Higher level baseline ETS exposure was associated with a greater risk of emergency department visits (OR 3.4; 95% CI 1.1 to 10.3) and hospital admissions for asthma at prospective follow up (OR 12.2; 95% CI 1.5 to 102). There was no clear relationship between gas stove use or woodstove exposure and asthma health outcomes.

CONCLUSION

Although gas stove and woodstove exposure do not appear negatively to affect adults with asthma, ETS is associated with a clear impairment in health status.

PURPOSE

To study the association of physician characteristics, the characteristics of their practice settings, patient mix, and reported frequency of prescribing asthma medication with patients' health status and health-related quality of life in asthma.

METHODS

We conducted a mail-back survey of physicians (n = 147) that included demographic characteristics, practice and training characteristics, and reported prescribing frequencies for common asthma treatments. We also conducted structured telephone interviews with 317 of their patients, assessing demographic characteristics, health status (as measured by the Short Form-12 [SF-12] physical component score), and asthma-specific quality of life (as measured by the Marks questionnaire).

RESULTS

In adjusted analyses, pulmonary specialists were more likely to report using leukotriene modifiers (odds ratio [OR] = 4.7; 95% confidence interval [CI]: 1.2 to 18) and theophylline (OR = 3.0; 95% CI: 1.0 to 9.0) in adult patients with asthma. Working in a practice of >75% health maintenance organization (HMO)- or preferred provider organization (PPO)-insured patients was associated with a lower likelihood of prescribing leukotriene modifiers (OR = 0.1; 95% CI: 0.01 to 0.5). Adjusting for patient demographic characteristics and steroid dependence, physician prescribing tendencies were not associated with patients' perceived health status or quality of life. Although an HMO- or PPO-predominant practice was associated with better physical health status (mean difference in SF-12 physical component score, 3.1; 95% CI: 0.05 to 6.2; P = 0.05), there was no statistical association with quality of life.

CONCLUSION

The characteristics of physicians, their practices, and the asthma medication prescribing strategies that they adopt are not strongly associated with patients' perceived outcomes.

BACKGROUND

Asthma is a common and costly health condition, but most estimates of its economic effect have relied on secondary sources with limited condition-specific detail.

OBJECTIVE

We sought to estimate the magnitude of direct and indirect costs of adult asthma from the perspective of society.

METHODS

We used cross-sectional survey data from an ongoing community-based panel study of 401 adults with asthma originally derived from random samples of northern California pulmonologists, allergist-immunologists, and family practitioners to assess health care use for asthma, to assess purchase of items to assist with asthma care, and to measure work and other productivity losses. Unit costs derived from public-use and proprietary data sources were then assigned to the survey items.

RESULTS

Total per-person annual costs of asthma averaged $4912 US dollars, with direct and indirect costs accounting for $3180 US dollars (65%) and $1732 US dollars (35%), respectively. The largest components within direct costs were pharmaceuticals ($1605 US dollars [50%]), hospital admissions ($463 US dollars[15%]), and non-emergency department ambulatory visits ($342 US dollars [11%]). Within indirect costs, total cessation of work accounted for $1062 US dollars (61%), and the loss of entire work days among those remaining employed accounted for another $486 US dollars (28%). Total per-person costs were $2646, $4530, and $12,813 US dollars for persons self-reporting mild, moderate, and severe asthma, respectively (P <.0001, 1-way ANOVA).

CONCLUSION

Asthma-related costs are substantial and are driven largely by pharmaceuticals and work loss.

BACKGROUND

Work-related symptoms and disability due to respiratory disease are common and costly among working-age adults. To investigate this problem, we analyzed data on respiratory symptoms related to the workplace and occupational disability from the European Community Respiratory Health Survey (ECRHS).

METHODS

The ECRHS is a population-based sample of adults aged 20 to 44, with oversampling of subjects with symptoms that are consistent with respiratory disease. We analyzed structured interviews from 17,567 subjects, of whom 15,039 were from a general random population sample and 2,528 were from the respiratory symptom oversample. We defined work-related respiratory symptoms as self-reported wheeze or chest tightness at work, and work-related respiratory disability as reported job change due to breathing difficulties at work. We used binary generalized linear modeling with a log link to estimate the risk of symptoms and disability.

FINDINGS

Wheeze at work was reported in the general population sample by 1,552 subject (10%), ranging from 4 to 15% among the 16 countries analyzed. Work-related respiratory disability was reported by 540 subjects (4%), ranging from 1 to 8%. Reported workplace exposure to vapors, gases, dust, or fumes was associated with increased risk of respiratory symptoms at work (prevalence ratio [PR], 2.1; 95% CI 1.8-2.4) and work-related respiratory disability (PR, 3.4; 95% confidence interval [CI], 2.0 to 5.1). Workplace environmental tobacco smoke exposure was associated with symptoms (PR, 1.3; 95% CI, 1.2 to 1.5) but not with disability (PR, 1.1; 95% CI, 0.9 to 1.4).

INTERPRETATION

These data indicated that work-related respiratory symptoms and disability vary widely in this international sample but, nonetheless, are associated with workplace exposures that could be addressed through preventive measures.

Although chronic obstructive pulmonary disease (COPD) is attributed predominantly to tobacco smoke, occupational exposures are also suspected risk factors for COPD. Estimating the proportion of COPD attributable to occupation is thus an important public health need. A randomly selected sample of 2,061 US residents aged 55-75 yrs completed telephone interviews covering respiratory health, general health status and occupational history. Occupational exposure during the longest-held job was determined by self-reported exposure to vapours, gas, dust or fumes and through a job exposure matrix. COPD was defined by self-reported physician's diagnosis. After adjusting for smoking status and demography, the odds ratio for COPD related to self-reported occupational exposure was 2.0 (95% confidence interval (CI) 1.6-2.5), resulting in an adjusted population attributable risk (PAR) of 20% (95% CI 13-27%). The adjusted odds ratio based on the job exposure matrix was 1.6 (95% CI 1.1-2.5) for high and 1.4 (95% CI 1.1-1.9) for intermediate probability of occupational dust exposure; the associated PAR was 9% (95% CI 3-15%). A narrower definition of COPD, excluding chronic bronchitis, was associated with a PAR based on reported occupational exposure of 31% (95% CI 19-41%). Past occupational exposures significantly increased the likelihood of chronic obstructive pulmonary disease, independent of the effects of smoking. Given that one in five cases of chronic obstructive pulmonary disease may be attributable to occupational exposures, clinicians and health policy-makers should address this potential avenue of chronic obstructive pulmonary disease causation and its prevention.

There is accumulating evidence that the workplace environment contributes significantly to the general burden of asthma. The purpose of this review is to explore the respiratory health and socioeconomic consequences of work-related asthma by addressing a series of controversial issues: 1) what is the natural history of occupational asthma and in what ways does ongoing exposure to the causal agent impact clinical outcomes?; 2) how does the natural history of irritant-induced asthma differ in its health outcomes from immunologically-mediated occupational asthma?; 3) do working conditions have a significant impact on asthma regardless of the aetiology of the disease?; 4) what is the scope of work disability from work-related-asthma in social and economic terms?; 5) what is the clinician's role in reducing the respiratory health consequences of work-related asthma? 6) to what extent do existing compensation and other social insurance schemes successfully address occupational asthma and work-aggravated asthma?

BACKGROUND

Gas stoves release respiratory irritants, such as nitrogen dioxide and other combustion by-products. Adults with asthma may be susceptible to the effects of gas stove exposure because of their underlying airway hyperresponsiveness, but this association has been difficult to establish.

AIMS

To examine the association between gas stove use and respiratory health.

METHODS

The analysis used data from the US Third National Health and Nutrition Examination Survey among 445 adults with asthma (representing 4.8 million persons with the condition).

RESULTS

Nearly half of the adults with asthma had a gas stove in their home (47.1%). There was no association between gas stove use and FEV1 (mean change 146 ml; 95% CI -50 to 342 ml), FVC (0 ml; 95% CI -151 to 152 ml), or FEF25%-75% (357 ml; 95% CI -7 to 722 ml). There was also no relation between gas stove use and the risk of self reported cough (OR 0.8; 95% CI 0.4 to 1.7), wheeze (OR 1.5; 95% CI 0.7 to 3.2), or other respiratory symptoms. Controlling for sociodemographic, smoking, housing, and geographic factors did not appreciably affect these results.

CONCLUSIONS

Among adults with asthma, there was no apparent impact of gas stove use on pulmonary function or respiratory symptoms. These results should be reassuring to adults with asthma and their health care providers.