Measures Of Asthma Severity Research Articles

Is home monitoring of lung function worthwhile for children with asthma?

Is home monitoring of lung function worthwhile for children with asthma?

Severe asthma: definition and mechanisms.

Severe asthma: definition and mechanisms.

Prevalence of mood disorders and relationship to asthma severity in patients at an inner-city asthma clinic

Depressive symptoms are associated with noncompliance and even sudden death in asthma patients. Some studies suggest that low-income, minority, inner-city asthma patients may be at high risk for asthma-related morbidity and mortality in which depression may be a risk factor. Minimal data are available on the prevalence of depression and other mood disorders in asthma patients. In this pilot study, we examined the prevalence of depression and the association between depression and measures of asthma severity in patients at an inner-city asthma clinic. Mood disorders were diagnosed using a diagnostic interview given to patients (N = 44) at asthma clinic visits. Inhaled steroid dose, FEV1 percentage, and asthma severity were also obtained. Eighteen patients (41%) had a lifetime mood disorder but only seven of these patients received pharmacotherapy. Patients with a past mood disorder had significantly higher FEV1 percentage predicted values (P = 0.03) than those without a mood disorder. Trends toward less severe asthma (P = 0.13) and lower inhaled steroid dose (P = 0.13) in patients with a mood disorder history were also found. The data suggest that mood disorders are common, but often unrecognized and untreated in asthma patients. The data also suggest that mood disorders are not necessarily associated with more severe asthma, at least in the population studied.

A childhood asthma severity scale: symptoms, medications, and health care visits

Although there are current measures to evaluate childhood asthma severity for clinical diagnosis and treatment, there is no standard valid measure to evaluate childhood asthma severity for large-scale epidemiologic studies. To develop and test a childhood asthma severity scale (CHAS) for clinimetric validity and to determine differences in symptoms, medication use, and health care visits by participant characteristics. Eight hundred ninety-seven actively asthmatic children under the age of 12 years were selected from a general population of children. Children were selected from a screening questionnaire administered at six Connecticut hospitals that serve large minority populations in Bridgeport, New Haven, Hartford, and Danbury and one hospital serving south central Massachusetts. Twelve-month baseline data for a prospective cohort study of childhood asthma severity were collected on a monthly basis through home interviews. Home interviews addressed questions on daily symptoms, medication use, and health care visits. A severity scale was constructed using three dimensions: symptoms, medication use, and health care visits. CHAS has sufficient preliminary content, construct, and predictive validity. Despite similarities in symptoms, there were health care utilization and medication differentials according to race and ethnicity, insurance status, family income, and maternal education. CHAS is a potentially useful measure of asthma severity for large-scale epidemiologic studies. It seems that CHAS has sufficient clinimetric properties.

Is home monitoring of lung function worthwhile for children with asthma?

In this issue of Thorax Kamps et al 1 point out that current guidelines for the management of asthma in children frequently advocate the use of home monitoring of lung function. This is supposed to provide an objective measurement of the status of the child's asthma that can be used to guide therapy. This situation has come about partly as a “trickle down” from guidelines for managing asthma in adults and partly through a recognition that many children have a poor ability to perceive and accurately report airway obstruction.2 An objective measure of asthma severity should therefore allow for more effective asthma management with a reduction in mortality and morbidity. Home monitoring with a portable peak expiratory flow (PEF) meter has been advocated as such a measure and included in many asthma management plans. In theory, PEF monitoring can provide both an indication of the degree of airway obstruction and an indication of variability of the obstruction. The rationale for using PEF variability is that it correlates, although weakly, with asthma symptoms and airway hyperresponsiveness.3-6 Portable PEF meters suitable for use in the home …

Association of asthma symptoms and severity with indoor bioaerosols.

In this study, repeated measurements were made of levels of mold spores, bacteria, and dust-mite allergens over a 7-month period in the homes of asthmatics, and relationships with measures of asthma severity were evaluated. A sample of 57 asthmatic individuals, living in 44 homes in East Moline, Illinois, and nearby communities, participated in a panel study. The homes were visited up to nine times during the study to collect air and dust samples. Asthma severity indicators were derived from questionnaire data and from the daily health records from the panel study. Associations between indoor levels of mold spores, bacteria, and dust-mite allergens were tested with several asthma severity indicators. There was evidence of associations between all asthma severity measures and levels of total and gram-negative bacteria, but mold-spore abundance was associated only with emergency room (ER) visits for asthma. No significant associations were found with house-dust-mite allergen and any of the asthma severity indicators, but the levels of dust-mite allergen were low, with median concentrations of 0.18 microg/g dust Der f 1 and 0.19 microg/g dust Der p 1. Some evidence was found for associations of increased concentrations of gram-negative bacteria and mold spores with asthma severity, particularly with ER visits. No association was found between house-dust-mite allergen and asthma severity indicators; however, the mite-allergen levels in the study homes were generally well below the proposed threshold level of 2 microg/g dust.

Effect of an Inhaled Glucocorticoid, Flunisolide, on Bone Mineral Density: A 2-Year Prospective, Controlled Trial

ObjectiveTo determine the long-term effect of an inhaled glucocorticoid, flunisolide, on bone mineral density in a prospective, controlled study. MethodsPatients with asthma treated with inhaled glucocorticoids, but not requiring other types of glucocorticoid treatment, were recruited as study patients (N = 11). All study patients were treated with inhaled flunisolide, 500 μ.g twice a day for a 2-year period, for consistency. Patients with asthma not requiring any type of glucocorticoid treatment were recruited as control subjects (N = 18). All patients were between the ages of 30 and 50 years, and all female patients were premenopausal. Measurements of bone mineral density, serum bone-specific alkaline phosphatase, serum osteocalcin, 24-hour urine hydroxyproline-to-creatinine ratio, forced expiratory volume in 1 second/forced vital capacity, and forced expiratory flow, midexpiratory phase were obtained at baseline and repeated in 1 year and again in 2 years. ResultsNo statistically significant changes were noted in bone mineral density measured at the lumbar spine, femoral neck, Ward’s triangle, or femoral trochanter in the users of inhaled flunisolide in comparison with the control subjects at 1 year or at 2 years, with one exception. The percentage change from baseline of bone mineral density measured at the femoral trochanter at 1 year was greater in the inhaled flunisolide users than in the control group, 3.1% versus –0.8%, respectively (P = 0.01). No statistically significant changes were found in markers of bone turnover or measures of asthma severity. ConclusionInhaled flunisolide, administered in standard doses, had no deleterious effect on bone mineral density or on biochemical markers of bone turnover after a 2-year period. (Endocr Pract. 2000;6:311-317)

271. Depression in asthma patients: preliminary findings

Data suggest that asthma and asthma-related deaths have increased in recent years. Depressive symptoms are reportedly associated with non-compliance and even sudden death in asthma patients. However, minimal data are available which correlate depressive symptoms or the presence of a mood disorder with subjective and objective measures of asthma severity. Preliminary data from two studies are reported. In the first study, forty-five consecutive asthma patients (9 males, 36 females, mean age = 51.2, SD = 13.2) were given the mood disorders component of the SCID-IV. Out of 6 patients with current major depressive disorder only one received an antidepressant. Surprisingly, patients with a mood disorder had significantly (p = 0.04) less severe airway obstruction (mean FEV1 = 73%) than those without a mood disorder (mean FEV1 = 61%). In the second study, twenty-six asthma patients (4 males, 22 females, mean age = 50, SD = 12.9) were given the Inventory of Depressive Symptomatology-Self Report (IDS-SR) and the SF-12 consisting of two self-reported subscales which measure mental and physical functioning. A significant relationship was found between higher IDS-SR scores and lower scores on both of the SF-12 subscales measuring mental (p = .02) and physical (p = .03) functioning. These results suggest that depression is associated with greater subjective but less objective ratings of medical disability. In addition, these data suggest that while mood disorders may be common in this population, asthma patients may be infrequently treated for depressive symptomology. The implications of these findings and directions for future research are discussed.

Clinically meaningful changes in quantitative measures of asthma severity.

To determine minimum clinically meaningful improvements in peak expiratory flow rate (PEFR) and dyspnea visual analog score (VAS) in patients with acute asthma exacerbation. Patients presenting to the emergency department (ED) with acute asthma exacerbation were eligible. The PEFR and VAS were assessed at presentation and after initial asthma therapy. During reassessment, subjects were asked to describe their asthma symptoms as "much better," "a little better," "no change," "a little worse," or "much worse." Correspondence between self-reported improvement and changes in PEFR and VAS was assessed. The "minimum clinically significant change" in either index was defined as the difference between pre- and posttreatment measures in subjects reporting their symptoms "a little better." One hundred fifty-six subjects were included. Asthma symptoms were "much better" in 99 (64%), "a little better" in 41 (26%), and "unimproved" (composed of patients describing symptoms as "no change," "a little worse," or "much worse") in 16 (10%). The mean VAS change among the "a little better" subjects was 2.2 cm (95% CI = 1.1 to 3.4), significantly greater than the -0.4 cm (95% CI = -2.1 to 1.4) change in the "unimproved" subjects. The mean change in percent predicted PEFR among the "a little better" subjects was 11.9 (95% CI = 7.3 to 16.1), not statistically different from the change of 6.1 (95% CI = 1.1 to 11.3) in the "no change" subjects. The "much better" group showed significantly greater changes in both measures than either of the other groups. A VAS change of > or =0.5 cm reliably discriminated between subjects with and without symptom improvement. Improvements in VAS of 2.2 cm and in predicted PEFR of about 12 percentage points are minimal clinically significant improvements during ED asthma therapy. The dyspnea VAS is valid in assessing symptomatic changes and may detect small subjective improvements better than the PEFR.

Do hormonal contraceptives influence asthma severity?

There is some evidence that endogenous progesterone and oestrogen levels influence asthma severity in females, but little is known about the effects of hormonal contraceptives. This study aimed to describe how females with asthma perceived the effects of hormonal contraceptives on symptom severity, and to describe the association between asthma severity and current use of hormonal contraceptives. A questionnaire was sent to 891 females with asthma aged 20-30 yrs recruited from general practice registers in South London, UK. It asked about perceptions of the effects of hormonal contraceptives on asthma severity, about current use of hormonal contraceptives, and included an asthma quality of life questionnaire as a measure of asthma severity. About 6% of respondents who had ever used hormonal contraceptives reported that these had influenced asthma severity, -4% reporting worsening and 2% an improvement. There were no significant differences in asthma quality of life score between females currently taking hormonal contraceptives and those not, between those taking combined and progesterone-only preparations, or between users of different progestagen types. This study found no evidence of any important effect of hormonal contraceptives or their components on asthma severity in a group of females with relatively mild asthma.

Association of Being Overweight with Greater Asthma Symptoms inInner-City Black and Hispanic Children

Luder E, Melnik TA, DiMaio MJ Pediatr.1321998699703The prevalence of both asthma and obesity have been increasing over recent years, and are higher among minorities. The aim of this study was to observe whether the weight status of inner-city minority asthmatic children differed from that of their nonasthmatic peers, and to determine if overweight asthmatic children experienced more severe asthma.The study group was composed of 209 black and Hispanic children between the ages of 2 and 18 who carried the single diagnosis of asthma, and who had not received chronic oral steroids or more than 4 short courses of oral steroids within the past year. The control group consisted of 1017 black and Hispanic children enrolled in New York City schools.Information obtained from the patient record and an interview was used to determine asthma severity. This information included peak expiratory flow (PEF) records, number of medications used, number of emergency visits or hospitalizations, number of school days missed, and ability to participate in play or sports activities. PEF rate was measured at enrollment in patients who were at least 6 years old and could perform a good effort. Standing height and weight were measured in the patients. Height and weight measurements for the control group were available for comparison. Body mass index (BMI) was calculated and used as the indicator of weight status. Differences in BMI between the asthmatic children and their peers were determined, and the relationship between high BMI and the various measures of asthma severity was examined.The percentile distribution of BMI for the children with asthma was compared with that of the control group as well as the established reference population. The BMI distribution for the asthmatic patients as well as the controls was skewed towards the higher percentiles compared with the reference population, but was skewed to a greater extent for the asthmatics. The asthmatic children had a relative risk of 1.34 of having a BMI at 85th percentile or greater compared with the peer group (P = .06). The relative risk for asthmatics of having a BMI at 95th percentile or greater was 1.51 (P = .03). The risk of being overweight (based on a BMI of 85th percentile or greater) was found to be significantly associated with days of school missed (30 days or more missed per year), PEF rate of ≤60% predicted, and three or more prescribed asthma medications. The risk of being overweight was not significantly associated with number of hospitalizations, number of emergency visits, or level of sports participation.The prevalence of being overweight was significantly higher in asthmatic children compared with their peers. Being overweight was significantly associated with severity of asthma as measured by PEF rate, days of school missed, and number of asthma medications.The authors mention that the findings of this study do not allow us to determine whether asthmatic children are more overweight because of a decreased activity level, or if being overweight actually leads to increased severity of asthma. Asthmatic children may be held back from participating in sports by their parents and thus become overweight because of inactivity. Alternatively, overweight children might spend more time indoors, thereby being exposed to greater amounts of indoor allergens, leading to increased asthma. The latter explanation might be more of an issue in inner-city environments.

Relationships between duration of asthma and asthma severity among children in the Childhood Asthma Management Program (CAMP)

Background: Many factors, including heredity, atopic status, and environment, have been implicated in the determination of asthma severity. Relatively little is known about the degree to which asthma duration influences asthma severity. Objective: The Childhood Asthma Management Program (CAMP), consisting of 1041 children (age 8.9 ± 2.1 years at enrollment) with mild-to-moderate asthma, offers an opportunity to examine the relationship between asthma duration and asthma severity. Methods: By using the extensive CAMP baseline cross-sectional data on asthma duration, spirometry, bronchial responsiveness, symptomatology, and markers of atopy, univariate and multivariate regression models were used to evaluate whether asthma duration is associated with asthma severity. Results: Duration of asthma in the study cohort from time of diagnosis until randomization into CAMP ranged from 0.3 to 12.1 years (mean, 5.0; SD, 2.7; median, 4.8). Asthma duration is associated in univariate analyses both with lower levels of several lung functions ( P < .001), including methacholine bronchial reactivity (natural log [ln] FEV 1 PC 20 , mg/mL; r = –0.112), prebronchodilator and postbronchodilator percent predicted FEV 1 ( r = –0.176 and r = –0.130, respectively), and prebronchodilator and postbronchodilator FEV 1 /forced vital capacity (FVC) (%) ( r = –0.237 and r = –0.211, respectively), as well as higher levels of symptoms (symptom score: r = 0.147, P < .001) and borderline greater use of albuterol for symptoms ( r = 0.058, P = .064) during a 28-day screening period before randomization. Simple linear regression detected the following differences in lung functions per year of asthma duration: ln FEV 1 PC 20 , –0.050 mg/mL/y; prebronchodilator FEV 1 , –0.907 percent predicted/y; and prebronchodilator FEV 1 /FVC, –0.729 percent predicted/y. After controlling for potential explanatory variables (atopy, inflammatory markers, household Der p 1 levels, anti-inflammatory medication use, and clinical center), regression models revealed that the duration of asthma remained significantly and independently associated with ln FEV 1 PC 20 ( P = .004), prebronchodilator percent predicted FEV 1 ( P = .043), and prebronchodilator and postbronchodilator FEV 1 /FVC (%) ( P < .001), as well as being positively associated with mean daily symptom score ( P < .001) and albuterol use for symptoms ( P = .003) during a 28-day screening period. Duration was also found to be significantly associated with physician/nurse assessment of asthma severity and other historical measures of medication use. Conclusions: These data demonstrate that asthma duration is associated with lower lung function, greater methacholine responsiveness, more asthma symptomatology, and greater use of as-needed albuterol, which are all measures of asthma severity. As such, early diagnosis and intervention may be necessary to ameliorate these adverse effects of persistent asthma. (J Allergy Clin Immunol 1999;103:376-87.)

Self-regulating childhood asthma: a developmental model of family change.

This article tests a model of self-regulatory development in which families' cognitive beliefs and behavioral skills for managing asthma symptoms emerge in four successive phases: asthma symptom avoidance, asthma acceptance, asthma compliance, and asthma self-regulation. Confirmatory factor analyses revealed that the hypothesized multiphase model provided the best factorial fit for phase items. Subsequent Guttman analyses of the families' phase scores revealed a high degree of sequential ordering. Finally, trend analyses of family phase differences revealed a significant negative linear relation with measures of asthma severity and a significant positive linear relation with physician care and concern measures, asthma regulatory measures, and beliefs in Western biomedical practices. Despite receiving primary care for asthma at a major metropolitan university hospital, 83% of the sample were classified as precompliant. The phase model of asthma self-regulatory development offers a qualitative approach for investigating the psychological determinants of asthma self-regulatory behavior.

Improving outcomes in elderly patients with asthma.

Although often regarded as a disease of childhood, asthma is common in elderly people. Although recent figures show a decline over the past few years in the number of asthma deaths in children and younger adults, the same is not true of older adults, in whom most asthma deaths occur. Differences between asthma in young and old patients are seen not only in response to treatment. The nonspecific presentation of asthma in elderly adults means that the diagnosis of asthma is difficult to make. In addition, research suggests that physicians are reluctant to use spirometry and measurement of reversibility when investigating respiratory symptoms in old people. This leads to a tendency to label breathless or wheezy elderly patients as having chronic obstructive pulmonary disease (COPD) rather than asthma. In turn, patients with a diagnosis of COPD are less likely to be treated with bronchodilators and corticosteroids. Treatment guidelines for the management of asthma in children and younger adults may need to be adapted when applied to older patients. Reduced perception of bronchoconstriction may lead to underuse of bronchodilators prescribed 'as required'. The bronchodilator response to beta2-agonists is attenuated as part of the normal aging process, and other groups of bronchodilator medications should be considered. Inhaler technique can be a particular problem in elderly patients with asthma, requiring careful choice of inhaler device. However, the frequent presence of multiple pathology and multiple medication in this age group enhances the risk of adverse effects from oral preparations, and so the inhaled route should be preferred wherever possible. Underestimation of the severity of an acute exacerbation of asthma by both patient and doctor has been suggested as a contributory factor to poor outcome in older people. Since the cardiovascular responses to hypoxia and bronchoconstriction tend to diminish with increasing age, objective measures of asthma severity (peak flow monitoring and blood gas estimation) are essential in this age group.

Respiratory Resistance in the Emergency Department: A Reproducible and Responsive Measure of Asthma Severity

To determine, in preschool children with an acute asthma exacerbation, the responsiveness to change of respiratory resistance measurements obtained by the forced oscillation (Rfo) technique, and to identify the magnitude of change indicative of airway obstruction reversibility. A prospective observational study of 114 children, aged 3 to 17 years, untrained in the Rfo technique and treated for acute asthma in a tertiary-care pediatric emergency department (ED). A physical examination followed by three measurements of respiratory resistance by forced oscillation were obtained at 8 Hz (Rfo8) and at 16 Hz (Rfo16). In cooperative children, routine spirometry that included FEV1 was also performed on the Custo Vit R (Custo Med; Munich, Germany). All measurements were obtained twice during the course of the ED treatment, before and after treatment with nebulized bronchodilators. The Rfo8 and Rfo16 measurements were highly reproducible (reproducibility coefficients >0.85). Both the Rfo8 and Rfo16 were at least as responsive to change (responsiveness coefficients of 2.3 and 1.2, respectively) as was FEV1 (2.0) and the four clinical signs most sensitive to change (0.6 to 1.0). A 19% change in Rfo8 was suggestive of significant reversibility. In the assessment of children aged > or =3 years with acute asthma exacerbation, the respiratory resistance measurements are highly reproducible and responsive to change, particularly when obtained at 8 Hz. A 19% change from baseline Rfo8 is suggestive of reversibility. This technique appears to be an attractive alternative in the evaluation of children who are too young or too sick to perform spirometry reproducibly.

Acute severe asthma treated by mechanical ventilation: a comparison of the changing characteristics over a 17 yr period

Recorded cases of asthma have increased in recent years. It is unclear, however, whether this apparent increase in prevalence is accompanied by an increase in severity of the disorder. One potential measure of asthma severity is the requirement for mechanical ventilation. This paper examines those patients ventilated for severe asthma in a district general hospital over a 17 yr period. Since the methods used to assess asthma attacks and the criteria for instituting mechanical ventilation in this hospital did not alter between 1973 and 1992 (Jones criteria), it was possible to compare directly characteristics of all ventilated patients during the study period. The comparison showed that there was a significant increase between the two study periods in the number of patients who required mechanical ventilation. Moreover, in the more recent period both the subjective speed of onset of the asthma attack and the objective time between admission and ventilation were significantly shorter. However, despite this increase in asthma severity the mortality and morbidity in the more recent study period were lower. Overall the results of this study support the view that, in the population served by our district general hospital, asthma has increased in severity. This increased severity is indicated by an increase in the number of patients requiring mechanical ventilation and in the rapidity with which attacks evolved. However, for patients in whom ventilation was required, improved care has lowered both morbidity and mortality.

Association of being overweight with greater asthma symptoms in inner city black and Hispanic children

Objective: To determine whether the weight status of inner city black and Hispanic children with asthma differs from that of their peers and to assess whether overweight asthmatic children experience greater asthma symptoms.Study design: A cross-sectional study in an ambulatory chest clinic of an inner city medical center. Methods: We studied black and Hispanic children aged 2 to 18 years ( n = 209) with the single diagnosis of asthma. The peer control subjects consisted of a sample of black and Hispanic children aged 6 to 13 years ( n = 1017), enrolled in the New York City schools. Asthma symptoms, the number of asthma medications prescribed, and peak expiratory flow rate (PEFR) measurements were used to classify asthma severity and relate to body mass index (BMI). Bivariate categorical analysis and χ 2 tests were performed to examine the relationship between high BMI and the individual measures of asthma severity. Results: The prevalence of overweight was significantly higher in children with moderate to severe asthma than in their peers. The risk of overweight based on a BMI in the 85th percentile or greater was significantly associated with the following measures of asthma severity: (1) the number of school days missed per year; (2) a PEFR less than or equal to 60% of the predicted PEFR; and (3) the number of asthma medications prescribed. Conclusions: The prevalence of overweight was significantly higher in children with moderate to severe asthma than in their peers, and being overweight was associated with significantly more severe asthma symptoms. Further studies in overweight asthmatic children are needed, including the effect of weight loss on lung function and other markers of asthma severity. (J Pediatr 1998;132:699-703.)

The responsiveness of disease-specific and generic health measures to changes in the severity of asthma among adults.

The objective of the study was to compare the validity of asthma-specific and generic health outcome measures in relation to changes in the severity of asthma and to treatment. Adult patients (n = 142) participating in a randomized placebo-controlled trial at six clinics were assessed at baseline, prior to the withdrawal (placebo) or continuation of treatment with Vanceril and again after 8 weeks. The criterion measures of change in severity included pulmonary function expressed as the percent predicted FEV1, five physician-assessed asthma severity measures (cough, chest tightness, wheezing, shortness of breath and overall condition) and two patient-assessed severity measures (night-time symptoms and overall symptoms). The 8 week change scores were estimated for all generic and specific measures and the results were compared across groups of patients who did and did not change in terms of clinical criteria of disease severity and across treatment groups. The responsiveness of each generic and specific measure was estimated independently using the relative validity (RV) methodology, which compares F-ratios for the mean change scores across measures in analyses of the same comparison groups. RV coefficients estimate how much worse each measure discriminated between comparison groups, relative to the best measure (RV = 1.0). Four standardized asthma-specific measures and a total scale score (based on the Marks questionnaire), an individualized asthma-specific scale measuring limitations in activities most important to each patient (based on the Juniper method) and two newly-developed scales measuring physical and psychosocial symptoms were used as outcome measures, generic health outcome measures included eight functional health and well-being scales as well as the physical and mental health summary scales from the SF-36 health survey. A standardized asthma-specific scale was most valid in discriminating between groups of patients who did and did not change according to all of the clinical criterion variables studied and in discriminating between treated and untreated groups. Different scales performed best, depending on the clinical criterion. The asthma-specific Marks breathlessness scale was significant in all nine comparisons (RV = 0.62-1.0) and was most valid in discriminating between groups in six of nine tests. The overall scale also performed well in all comparisons (RV = 0.58-1.0). The newly-developed physical symptoms scale was significant in discriminating between groups in eight out of nine tests (RV = 0.52-1.0) and was most valid in three of the nine, including the treatment comparison. The psychosocial impact scale discriminated significantly in eight of the nine comparisons (RV = 0.16-0.38), but was less valid than other specific measures. The asthma-specific individualized activities scale discriminated significantly in seven of the nine tests, but performed less well than the other specific measures (RV = 0.21-0.35) and was not significant in the treatment comparison. One or more SF-36 scales discriminated significantly between groups in all nine comparisons. Two of those scales (physical functioning and role-physical) were consistently more valid than the others (RV = 0.17 and 0.58, respectively) and were the only two generic scales that discriminated between groups of patients defined in terms of changes in FEV1 (RV = 0.26-0.58). The SF-36 physical summary scale discriminated significantly between groups in all nine comparisons (RV = 0.19-0.61) and was the most valid generic measure in the treatment comparison (RV = 0.55). The SF-36 mental summary scale was significant only for the two patient-assessed changes in disease severity (RV = 0.31 and 0.32) and for physician-assessed overall severity (RV = 0.12). A comprehensive battery of generic and specific measures is likely to be most useful in understanding the impact of changes in disease severity on the functional health and well-being of adults with asthma, a

Toward a Simplified Measure of Asthma Severity for Applied Research

There is no universally accepted and validated measure of asthma severity. For community research, clinical tests are too costly, and epidemiological assessments provide inadequate data on severity. Symptom measures may offer a practical alternative. This study assessed psychometric properties of symptom ratings of 91 asthmatic children. Reliability and validity of scales created from these items were examined. A sum scale of symptom ratings was internally consistent, reliable across time, and associated with concurrent health indices. This scale may be a practical measure of severity for use in community-based research.

The Association Between Asthma Drugs and Severe Life-Threatening Attacks

To measure the association between asthma drugs and death or ICU admission due to asthma (severe life-threatening attack of asthma [SLTA]), and to assess the possibility that these associations may not be causal but due to the prescription of these drugs to patients with more severe disease (confounding). Retrospective cohort study of 655 asthmatics who attended an emergency department in 1986 to 1987 followed till death or May 1989. Outcome events were death or ICU admission due to asthma (SLTA). All hospital attendances were identified and patients classified at each according to drug exposure and a wide variety of measures of asthma severity. Incidence rates were computed as total outcome events divided by person-time contributed for each subject classified according to drug use and asthma severity. Rate ratio (RR) estimates for severe asthma outcomes associated with use as compared to nonuse of asthma drugs were calculated. Severity markers were identified and used to adjust the crude RR estimates. One hundred five SLTAs (15 deaths, 90 ICU admissions) occurred in 66 patients. Like inhaled fenoterol, oral beta-agonists, theophylline, cromolyn, inhaled steroids, and oral steroids were all associated with an increased risk of SLTA. When adjusted progressively for measures of severity, these increased risks became insignificant except for cromolyn. Unadjusted RR estimates for severe asthma events comparing exposure to a particular drug with nonuse are overestimates due to confounding. Control with two severity markers (hospital admission in the last year, use of oral corticosteroid at the time of previous admission) removes some confounding but control for additional severity markers not available in previous studies reduces the effect estimates further. These results suggest that the problem of confounding is substantial in nonrandomized epidemiologic studies of asthma drugs. Previous studies reporting RR estimates are likely to be confounded.