Assessment of the severity of asthma in a family practice

Assessment of an asthma quality of life scale using item-response theory

OBJECTIVE

Health-related quality of life (HRQOL) scores produced by simply summing individual item values have been criticized for lacking linearity and for not being equally discriminating across the range of scores. Differences in summed scores may depend more on their starting point on the scale rather than actual differences in the underlying dimension of HRQOL, making it difficult to judge what a particular score means. We sought to examine the usefulness of an alternative method of scoring questionnaires, item-response theory (IRT), for the clinical interpretation of a modified version of the Marks Asthma Quality of Life Questionnaire (MAQLQ-M).

METHODOLOGY

Using the MAQLQ-M, we surveyed 293 adults with moderate to severe asthma, managed at two university teaching hospitals in Adelaide, South Australia. Scores obtained by usual summative Likert-type scores were compared to estimates using the partial credit method of IRT.

RESULTS

We found a non-linear relationship between raw, summative scores and the IRT estimates. The departure from linearity was marked for summative scores below 3.0 and above 5.0 (range 1.0-7.0), values that included half of the study patients. Summative scoring did not produce scores at the interval level of measurement.

CONCLUSION

For an equivalent difference measured in the underlying dimension of actual HRQOL using IRT, traditional summated scores showed a much smaller difference in scores at both the lower and upper end of HRQOL, than at the mid-range of HRQOL. Caution should be used when interpreting HRQOL surveys scored in the usual summative manner. Advantages may be gained by using IRT as an alternative method of scoring HRQOL questionnaires.

Clinical practice guidelines: medical follow-up of patients with asthma--adults and adolescents

The follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks).

A narrative review shows the unvalidated use of self-report questionnaires for individual medication as outcome measures

OBJECTIVE

Accurate individualized data on drug consumption is required for a number of purposes. While electronic medication event monitoring is the best objective measure available, self-report tools would be a useful alternative in certain situations. We searched for validated self-completion questionnaires suitable for measuring change in medication.

METHODS

A systematic search of the English language literature since 1980, and a narrative literature review.

RESULTS

Few articles described the development or use of self-report methods to measure change in medication over time. We found no questionnaire that was commonly used for this purpose, nor one that had been evaluated and published. Considerable work has been undertaken to develop questionnaires or diaries for individual projects, but because these tools and their validation are rarely published, they are not available for other researchers to use, and comparison across studies is difficult. Some work has been done developing diary formats and the Medication Quantification Scale converts complex medication change data to a single numerical score.

CONCLUSION

Medication change is rarely considered as an outcome, and when it is measured, nonstandardized methods are used. More attention needs to be given to developing self-report tools and validating them across a range of criteria.

Variation in the distribution of patient-reported outcomes based on different definitions of defining asthma severity

OBJECTIVES

The purpose of this study was to observe the variation in the distribution of health-related quality of life and work performance scale scores based on using different methods of determining asthma severity.

METHODOLOGY

Five methods of determining asthma severity were used, including three patient-derived measures (patient perceived severity or PPS; overall symptom-derived severity or OSS; and nocturnal symptom-severity or NSS); and 2 methods using retrospective pharmacy claims (reliever/oral steroid use or ROSU and multi-drug use or MDU). Three levels of severity were examined: mild, moderate, and severe, requiring condensing some severity categories of several methods. Data were obtained from a cross-sectional mail survey of 603 adults with asthma in a US managed care organization linked to pharmaceutical/medical claims data. Patient-reported outcomes included the Physical Component Summary Score (PCS) and the Mental Component Summary Score (MCS) of the SF-36, the summary score (AQLQ) of the Asthma Quality of Life Questionnaire, and the Work Performance Scale score (WPS) of the perceived work performance scale of the Functional Status Questionnaire. Analysis of variance (ANOVA) was used to examine each method's ability to distinguish between severity levels. Descriptive statistics were used to observe differences in scale scores between methods.

RESULTS

Within each method, significant severity effects (except MDU) were found for PCS, AQLQ, and WPS. In post-hoc analyses, mild-moderate and mild-severe comparisons were consistently significant (p < 0.05). In the cross-method analyses, method effects were found at all levels of severity for most scale scores with ranges increasing with increases in severity level. Within-method results were consistent with previous studies demonstrating a significant relationship between severity, health-related quality of life (HRQL) and work performance (WP). However, HRQL and WP scale scores varied by the method used to define severity.

CONCLUSION

This variation should be considered when performing cross-study comparisons of burden of illness and treatment effects.

Developing the Medication Change Questionnaire

OBJECTIVE

People who seek non-pharmaceutical interventions are often motivated by a desire to avoid or reduce orthodox medication. Effectiveness research in these areas needs to measure change in medication as an outcome. We set out to develop a data collection tool that is sensitive to changes in individual drug use over time.

METHOD

A multi-disciplinary team designed, piloted, and revised the Medication Change Questionnaire (MCQ) on two occasions, and used qualitative interviews to understand the patient's perspective and ensure that the final product accurately reflected the medication that patients were taking. Thirty patients in one general practice completed the questionnaire on two occasions and a purposive sample of 14 were interviewed. The design sought to enable patients to record all their ingested medication accurately, both prescription and over-the-counter drugs, over a period of 7 days. It was designed to be administered face-to face on the first occasion, and to be self-completed on subsequent occasions.

RESULTS

In considering in detail what medication was taken each day, the interview data fully correlated with the MCQ data in only one of the five people who were interviewed after completing the first draft of the questionnaire, but in eight of the nine people who completed the second draft. Of these eight people all but one had made some change to their medication, either by stopping or starting a drug, varying the dose of a drug or always taking one or more drugs in varying doses. The interviews demonstrated the complex and individual ways that people took their medicines, and the disparity between what was prescribed and what was actually taken. The qualitative data were also useful for reflecting on the potential advantages and disadvantages of other data collection methods, such as single medication questions and pill counts.

CONCLUSION

By involving patients at every level of research, we have developed a questionnaire that enables people to record their medication use accurately over a 7-day period, and to demonstrate changes in medication over time. Further work is required to assess its acceptability by different patient populations and its feasibility in terms of completion rates over longer periods of repeated use. We believe the MCQ to be an improvement over the variety of ad-hoc tools used in the past and it is freely available from the authors.

Patient and physician evaluation of the severity of acute asthma exacerbations

We studied the ability of patients not experienced in the use of peak expiratory flow meters to assess the severity of their asthma exacerbations and compared it to the assessment of experienced clinicians. We also evaluated which data of physical examination and medical history are used by physicians to subjectively evaluate the severity of asthma attacks. Fifty-seven adult patients (15 men and 42 women, with a mean (+/- SD) age of 37.3 +/- 14.5 years and 24.0 +/- 17.9 years of asthma symptoms) with asthma exacerbations were evaluated in a University Hospital Emergency Department. Patients and physicians independently evaluated the severity of the asthma attack using a linear scale. Patient score, physician score and forced expiratory volume at the first second (FEV1) were correlated with history and physical examination variables, and were also considered as dependent variables in multiple linear regression models. FEV1 correlated significantly with the physician score (rho = 0.42, P = 0.001), but not with patient score (rho = 0.03; P = 0.77). Use of neck accessory muscles, expiratory time and wheezing intensity were the explanatory variables in the FEV1 regression model and were also present in the physician score model. We conclude that physicians evaluate asthma exacerbation severity better than patients and that physician's scoring of asthma severity correlated significantly with objective measures of airway obstruction (FEV1). Some variables (the use of neck accessory muscles, expiratory time and wheezing intensity) persisted as explanatory variables in physician score and FEV1 regression models, and should be emphasized in medical schools and emergency settings.

Diurnal variability of peak expiratory flow

Diurnal variation in peak expiratory flow (PEFvar) has been suggested as a surrogate for bronchial hyperreactivity, and may be a useful tool in the management of bronchial asthma. Several indices have been postulated to measure PEFvar; however, the number of daily measurements and the timing of recordings are not clearly established. Although several investigators have defined ranges for PEFvar in healthy individuals, clear cutoff values that differentiate asthmatics from others are not available. Despite this shortcoming, PEFvar is an important measurement in screening and diagnosis of asthma in population-based studies, as well as for assessing disease severity and prognosis. Treatment of asthma with either inhaled corticosteroids or bronchodilators may influence the magnitude of PEFvar in a complex fashion. Therefore, PEFvar should only be interpreted in conjunction with other clinical and laboratory information.

Use of changes in symptoms to predict changes in lung function in assessing the response to asthma therapy

BACKGROUND

The majority of adult patients with asthma are managed by primary care providers. Although there is no generally accepted gold standard for the assessment of asthma severity in general practice, treatment decisions and modifications to therapy are strongly influenced by patients' symptoms and history of asthma medication use.

OBJECTIVES

The primary goal of this study was to determine whether there is a correlation between changes in asthma symptoms during treatment and changes in lung function, as measured by peak expiratory flow (PEF). A secondary goal was to compare the relative efficacy (in terms of improvement in asthma symptoms and lung function) of 3 commonly used asthma treatments: inhaled fluticasone propionate, inhaled salmeterol xinafoate, and oral zafirlukast.

METHODS

This was a retrospective comparison employing regression analyses of asthma symptom and lung function data from 2890 male and female adolescent and adult patients with persistent asthma who were enrolled in 8 randomized, double-blind, double-dummy, parallel-group studies. Data on patients' self-rated symptoms, PEF, supplemental albuterol use, nighttime awakenings, and frequency of asthma exacerbations were used to ascertain whether there was a correlation between changes in asthma symptoms and changes in pulmonary function, and to compare treatment effects.

RESULTS

Changes in patients' ratings of asthma symptoms after treatment with study medications showed a strong correlation with changes in lung function. Similarly, changes in lung function were strongly correlated with changes in supplemental beta-agonist use and quality of life. In addition, fluticasone or salmeterol treatment resulted in significantly greater increases in mean morning PEF (P < 0.001), significantly greater decreases in symptom scores (P < or = 0.004), significantly fewer nights with awakenings due to symptoms (P < or = 0.017), and significantly greater reductions in supplemental beta-agonist use (P < 0.001) compared with zafirlukast treatment or placebo. Patients treated with fluticasone or salmeterol also experienced significantly lower rates of asthma exacerbation (3%) during treatment than did those receiving zafirlukast (7%) or placebo (12%) (P < 0.001 and P = 0.015, fluticasone and salmeterol, respectively).

CONCLUSION

These findings support the validity of primary care practitioners' basing asthma-management decisions on patients' symptoms.

Correlation between objective measures of airway calibre and clinical symptoms in asthma: a systematic review of clinical studies

Clinical symptoms are often used as a measure in asthma management, but a variety of symptoms and scales are available. The objectives of this systematic review were as follows: (a) to present correlations between symptoms and measures of airway calibre; (b) to present the scoring systems/ scales used in the publications. In the review, more than 10 000 publications were found under the key words: asthma and symptom(s). Twenty-one remained when FEV1/PEF, scale/score and correlation were added as key words. In summary, no standardized method exists for measuring asthma symptoms with respect to severity. This is the case for both the symptoms and the scales. There are two recently-developed asthma-control scales available (one of which has not yet been published and is not included in the review).

How the discrepancy between symptoms and peak expiratory flow rate influences evaluation of asthma severity

BACKGROUND

Recent asthma guidelines recommend the assessment of severity levels based on the most severe symptoms and peak expiratory flow rate (PEFR). Discrepancies are frequently encountered in the use of these variables in determining the severity levels of asthmatics. The objective of this study was to determine the difference in asthma severity levels as assessed by either symptoms alone or by PEFR alone, as compared with the assessment by the asthma guidelines.

PATIENTS AND METHODS

Severity levels that were determined by recent asthma guidelines for 60 asthmatic patients were reassessed, based on symptoms alone and PEFR alone. They were compared for any significant differences to the asthma guidelines.

RESULTS

Asthmatics were aged between 15 and 70 (mean 34) years, and 63.8% were females. Severity levels by symptoms alone were different from the guidelines in 27 cases (45%). Of these, 89% showed a tendency toward higher severity levels. Severity levels by PEFR alone were different in only three cases (5%). In both comparisons, differences of severity levels were significant (P<0.0001), but assessment by symptoms alone showed more deviation (x(2) =162.1) than PEFR alone (x(2) =73.1).

CONCLUSION

The study documented significant discrepancies in asthma severity assessed by symptoms alone and PEFR alone, when compared to the recent asthma guidelines. Severity assessed by symptoms alone showed lower levels, and the use of PEFR tended to categorize some asthmatics into a more severe level.

Assessment of asthma severity in adults with asthma treated by family practitioners, allergists, and pulmonologists

OBJECTIVES

Accurate measurement of asthma severity is critical for research evaluating asthma health outcomes. There are, however, no widely accepted asthma severity measures. A severity-of-asthma score, which is based on self-reported information, was previously developed and validated in subjects recruited from pulmonary and allergy subspecialty practices. The purpose of this study was to validate the severity-of-asthma score in subjects treated by family practice physicians and to compare asthma severity in subjects treated by family practitioners (n = 150) with those seen by allergists (n = 217) and pulmonologists (n = 384).

METHODS

The study was an ongoing panel study of adults with asthma. Subjects were a random sample of board-certified family practice, allergy, and pulmonary physicians. Each physician registered patients with asthma aged 18 to 50 years. Of 869 subjects registered, 751 (86%) completed structured telephone interviews. The family practice panel was recruited approximately 3 years after the subspecialty panel.

RESULTS

In the family practice subjects, the severity-of-asthma score demonstrated internal consistency (Cronbach's alpha 0.76) and concurrent validity, correlating strongly with asthma-specific quality of life, SF-36 General Health and Physical Functioning scales, and subject-perceived asthma severity. After controlling for demographic characteristics, a 5-point score increment was associated with increased emergency department visits, urgent physician visits, and restricted activity days. The mean severity score was highest in the pulmonary group (11.8 +/- 6.3), followed by the allergy (10.3 +/- 5.3) and family practice (9.3 +/- 5.5) groups.

CONCLUSIONS

The severity-of-asthma score was a valid measure in generalist-treated subjects. Asthma severity varied significantly by physician specialty.