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1 Dept of Clinical Pharmacology, Groningen University Institute of Drug Exploration, and 2 Dept of General Practice, University of Groningen, the Netherlands
CORRESPONDENCE: F.M. Haaijer-Ruskamp, Dept of Clinical Pharmacology, University of Groningen, Ant. Deusinglaan 1, 9713 AV, Groningen, the Netherlands. Fax: 31 503632812. E-mail: f.m.haaijer-ruskamp@med.rug.nl
Keywords: Asthma, drug treatment, guidelines, primary care, quality of life
Received: July 18, 2002
Accepted December 15, 2003
This work was funded by an unconditional scholarship from the Groningen University Institute of Drug Exploration (GUIDE) awarded to L.G. Pont.
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Abstract |
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The suitability of 146 asthmatics' medication regimes was determined according to the 1997 NIH asthma guideline. Quality of life was assessed on a seven-point scale using the Asthma Quality of Life questionnaire.
Just over half of the patients were not currently using the treatment considered necessary for controlling their asthma. Patients treated according to the guideline (n=72) had a significantly higher overall HRQL than patients with non-guideline treatment (5.7 versus 5.3). The differences were also significant for the subscales measuring symptoms and environmental exposure, but not for activities or emotional function.
An association between non-guideline treatment and a poorer health-related quality of life in asthma patients treated in general practice was observed. This study supports the role of evidence-based guidelines in daily practice. Further studies are needed to determine if guideline treatment is responsible for the increase in health-related quality of life observed in this work.
Asthma is a chronic inflammatory airway condition affecting >8% of adults in Western Europe 1. Like most chronic conditions, the majority of asthma patients are managed in general practice 2. International consensus regarding optimal treatment for asthma has existed since the early 1990s, as evident in the international guidelines first published in 1992 3. These guidelines aimed to help healthcare professionals bridge the gap between current knowledge and daily practice, and to standardise and improve the quality of asthma care provided. Over the past decade these guidelines have been reviewed and updated 4, and at the time of the current study in 1999/2000 the most recent international guideline was that published in 1997 by the National Institute of Health (NIH) 5. Pharmacotherapy is an important element in the optimal management of asthma as recommended in the guidelines. Common to all versions of the guidelines, the goals of asthma therapy are to improve the patient's quality of life by preventing chronic and troublesome symptoms, maintaining "normal" lung function, maintaining normal activity levels, preventing recurrent exacerbations and providing optimal pharmacotherapy with minimal adverse effects.
While the goals of asthma therapy focus on the patient, assessment of the guidelines and their effectiveness has focused on physicians. Little attention has been given to the effect of guidelines on patient outcomes, such as mortality, morbidity or quality of life in asthma. Prescriber adherence to the asthma guidelines with respect to diagnostic procedures, drug therapy and patient self-management counselling has been investigated 2, 6–8. While explicit guidelines have been shown to improve physician clinical practice, it is not known if such improvement has similar positive effects on patient outcomes 9, 10. Earlier work on the effect of guidelines on patient outcomes concluded that there was little evidence that clinical guidelines are effective in improving patient outcomes, although the poor quality of the guidelines investigated was believed to have had a major influence on this finding 11. More recent work has indicated that asthma patients receiving guideline-recommended drug therapies have less hospital admissions 12, 13 and better lung function 14 than patients not treated according to the guidelines. What remains unknown is the effect of guidelines on the patient's asthma-related quality of life. In this study, health-related quality of life (HRQL) in asthma patients managed in general practice who are treated according to the NIH asthma guideline were compared with the HRQL in those not receiving guideline recommended treatment.
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Materials and methods |
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All patients were aged 18–49 yrs with an anti-asthma medication (Anatomical Therapeutic Chemical classification group R03 15) or an asthma contact (International Classification of primary Care code R96 16) during 1997. Data from 1997 was used for recruitment to ensure that patients had chronic asthma. Patients no longer registered with an RNG doctor or receiving anti-asthma medications for nonasthma indications were ineligible. GPs invited eligible patients to attend a clinical appointment with a research assistant. A reminder letter was sent to nonrespondents within 3 months of the initial invitation. Anonymous age and sex, and prescribing data for nonresponding patients was obtained from the database to enable comparison between nonresponders and patients participating in the study. The local medical ethics committee approved the study and informed consent was obtained from each participant.
Methods
Participating patients attended a single research appointment (May–December 2000) where forced expiratory volume in one second (FEV1) was measured and a questionnaire regarding recent asthma symptoms, medication use and asthma-related quality of life was completed by each participant. FEV1 was assessed by an experienced research assistant trained in spirometry according to the standards of the American Thoracic Society using a Microlab 3300 spirometer (Micro Medical Ltd, Rochester, UK). For each participant the best of three readings was used.
Definition of guideline adherence
Each patient's treatment regime, as obtained from the interviews, was classified as adherent or nonadherent using an algorithm based on the recommendations from the NIH Expert Panel Report 2 Guidelines for the Diagnosis and Management of Asthma 5. Adherence to the guideline was defined as any drug or drug combination recommended in this international asthma guideline for the relevant asthma severity (table 1
). Since improving lung function and reducing symptoms are important treatment aims, drug combinations from higher asthma severity classifications were also considered adherent for patients with a lower severity classification.
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Since there is no objective severity classification for treated asthma patients, the severity classification from the international NIH guideline for pharmacological management of asthma was used 5. This classification uses a combination of symptoms and lung function to determine asthma severity rather than relying on a single component. In accordance with these NIH criteria (table 1
), questions referring to the frequency of night-time symptoms (less than twice a month, more than twice a month, once a week, more than once a week) and day-time symptoms requiring bronchodilator use (0–3 days per week, 3–6 days per week, 1–2 times per day, 
3 times per day) were used in combination with the FEV1 as assessed at the research appointment to classify the patients. Patients were assigned to the most severe grade in which a feature occurs. For example, a patient with night-time symptoms less than twice a month, but symptoms once to twice a day, and a FEV1 of 70% was assigned in class 3.
Health-related quality of life assessment
HRQL was assessed using the Adult Asthma Quality of Life Questionnaire (AQLQ) 19. The AQLQ is a validated disease-specific quality of life questionnaire consisting of 32 items measuring four domains of asthma-related health: 12 items assess symptoms, five measure emotional function, four assess exposure to environmental stimuli and 11 determine activity limitations due to asthma. The AQLQ uses a seven-point scale where a higher score corresponds to a better HRQL. Each participant completed the self-administered, Dutch language version of this instrument during the research appointment.
Sample size
In earlier studies using the AQLQ, the mean score for asthma patients treated in general practice ranged 4.6–6.0 20. In order to detect a difference in HRQL of 0.5, 63 patients with adherent and 63 with nonadherent treatment regimes were required. Previous work clinically assessing asthma treatment found the proportion of patients with pharmacotherapy not adherent to that recommended in the guidelines to be 
60% 2, 7. Thus, the study aimed to recruit 160 patients in order to achieve a power of 0.80 with an alpha of 0.05.
Analysis
An unpaired t-test was used to assess the difference in overall HRQL and in scores on the four subscales between asthmatics treated according to the guidelines and those with non-guideline treatment.
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Results |
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Medication use
Patients' severity classification and current asthma medication use are shown in table 2. Six patients (4.1%) reported using no current asthma medications. Of the 38 patients not using a short-acting ß-agonist, six were using ipratropium, 11 a long-acting ß-agonist, and two were using both. Salbutamol was the most commonly used short-acting ß-agonist used by 88.2% (90/102) of patients reporting use of a short-acting ß-agonist. Of the remaining short-acting ß-agonist users 12 used terbutaline and one each rimiterol and fenoterol. One patient was using both salbutamol and terbutaline, and one patient salbutamol and rimiterol.
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Non-guideline treatment regimes
Just over half of the treatment regimes were considered as nonadherent to guideline recommendations (table 2). Of the 14 patients in severity class 1 not using a short-acting ß-agonist, none were using ipratropium and two were using a long-acting ß-agonist. The majority of these patients (n=12) were using inhaled corticosteroids.
The main reason for nonadherent therapy among class 2 patients (n=5) was the lack of anti-inflammatory treatment (n=4). One patient was using anti-inflammatory treatment and a long-acting ß-agonist.
Lack of anti-inflammatory treatment was also a major factor contributing to nonadherent treatment for patients in asthma severity class 3. Of the 40 patients with a treatment regime not recommended in the guideline, 27 were not currently using any anti-inflammatory medication and one was using cromoglycate in place of the inhaled corticosteroid recommended in the guideline. Eighteen class 3 patients were not using a short-acting ß-agonist. From these 18, five were using ipratropium, four a long-acting ß-agonist and one was using both. There were six patients in this severity class with neither a short-acting ß-agonist nor an inhaled corticosteroid.
In severity class 4, the most severe class, there were 13 patients without a guideline-recommended treatment regime. Of the ten patients with no short-acting ß-agonist, one had ipratropium, five a long-acting ß-agonist and one had both. Three patients had no anti-inflammatory medication and one was using cromoglycate in place of an inhaled corticosteroid. There were six patients without either a long-acting ß-agonist or ipratropium.
Health-related quality of life
For the total patient population, the mean HRQL was 5.5±1.0. The HRQL was observed to decrease as asthma severity increased from 6.1±0.7 for patients in severity class 1, 5.5±0.4 for severity class 2, 5.2±0.9 for severity class 3 and 4.8±1.2 for severity class 4.
As seen in table 3, asthma patients treated according to the guideline had a significantly higher HRQL than those with non-guideline regimes (5.7 versus 5.3, p<0.01). For all four subscales, there was a positive difference for patients treated according to the guideline, which was significant for the domains "symptoms" and "environmental exposure".
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Discussion |
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The current study showed that asthma patients treated according to the NIH guideline also have a significantly better HRQL than patients not treated according to this guideline, especially in terms of symptoms and environmental exposure. It has been argued that clinical relevance of differences in quality of life is of more importance to the prescriber than statistical significance 21. A difference of 0.5 points on the AQLQ has been determined to represent a clinically relevant difference for measuring change within a single patient allowing for individual variation 22. However, AQLQ scores were compared between two patient groups where it can be expected that the individual variation within the two groups should be similar and a smaller difference could be considered clinically relevant. Thus the differences observed of 0.4 points in overall HRQL, as well as in the symptoms subscale, and of 0.6 points in the environmental exposure subscale are not only statistically significant but also borderline clinically relevant. Non-guideline treatment seems to have the least effect on emotional function of the asthma patients, which is in line with other studies in which the treatment regime appeared to have more impact on symptoms and environmental exposure than on emotional function 23.
In general, the HRQL among the patients participating in the study (mean 5.5) was relatively high. Other studies have also found that the average HRQL in mild-to-moderate asthma patients is close to that of the general population 24. A strong link between asthma-related quality of life and disease severity has been reported 20, 25, and this relationship was also observed in the current study. For all patients, irrespective of their treatment, the HRQL decreased from 6.1 for severity class 1 patients to 4.8 for the most severe patients, which is similar to that seen in other studies 20. It is most likely that the relationship between HRQL and asthma severity is due to the relationship between HRQL and asthma symptoms 26, 27.
Since no objective severity classification for treated asthma patients exists, the severity classification presented in the NIH guideline was used in the current study 5. This classification uses a combination of day-time and night-time symptoms, need for inhaled short-acting ß-agonist and lung function to determine asthma severity. It is often used to categorise patients in research, but may underestimate actual severity in patients that are well controlled with treatment 28. In a first attempt to validate the assessment of asthma severity in patients mostly taking treatment, it was concluded that the severity classification recommended by clinical guidelines, such as the NIH, is useful for clinical assessment and management of asthma patients in general practice 29. In the current study, a possible underestimation of severity does not affect the assessment on whether the treatment is adherent to the guideline, because treatment recommendations follow a step-wise progression. Treatment for a higher severity is always in addition to treatment from a lower severity either with respect to increasing the dose of an existing medication or the addition of a new medication. Thus, adequate treatment according to the guideline for a particular severity class implies that the treatment will also be considered adequate for a lower severity class.
While the response rate in this study was rather low (40%), sufficient numbers of patients with adherent and with nonadherent treatment regimes were recruited. There were no large differences between participants and nonrespondents in terms of age, sex or prescribed medication. The low response rate may be related to the age group targeted (18–49 yrs), since this group comprises a large proportion of the workforce and may be less willing to attend the research appointment.
To determine the patients' current asthma medication regime, each patient was questioned about their asthma medications using both brand and generic names, as well as having each patient bring their current medications along to the clinical appointment. The method focuses on what the patient is currently using, either daily or as needed, and not necessarily on what the doctor has prescribed. It has been reported that specific patient groups do not redeem as many as 27% of prescriptions 30, thus a doctor may have prescribed a guideline-based regime that a patient has chosen not to have dispensed. This indicates that from a GP's perspective this study may underestimate the proportion of patients being prescribed medication according to the guidelines.
In conclusion, a significant proportion of non-guideline treatment in asthma patients in general practice was observed, which was associated with a poorer health-related quality of life. Further studies are needed to determine if treatment adhering to that recommended in the guidelines is responsible for the better asthma-related quality of life observed in this work. For doctors and other healthcare professionals this study emphasises the relevance of using evidence-based treatment guidelines in daily medical practice.
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