Validation of the Asthma Quality of Life Questionnaire (AQLQ UK English Version) in Indian Asthmatic Subjects

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1 ORIGINAL ARTICLE Validation of the Asthma Quality of Life Questionnaire (AQLQ UK English Version) in Indian Asthmatic Subjects Sunil K. Chhabra and Shivu Kaushik Department of Cardiorespiratory Physiology, Clinical Research Centre, Vallabhbhai Patel Chest Ititute, University of Delhi, Delhi, India ABSTRACT Background. The Asthma Quality of Life Questionnaire (AQLQ) has been shown to have strong measurement properties. Quality of life itruments need to be validated under local conditio before these can be accepted for application in that community. The AQLQ has not been formally validated in India. Objectives. To measure the evaluative and discriminative properties of the AQLQ (UK English version) in Indian asthmatics. Methodology. Thirty-eight adult patients with asthma underwent spirometry and completed the AQLQ and the Asthma Control Questionnaire (ACQ), administered by an interviewer. Standard treatment was given for four weeks during which daytime and nocturnal symptoms of asthma, and use of rescue medication were recorded in diaries. The questionnaires were administered again at the end of four weeks and spirometry was repeated. Results. The total and domain-wise scores of AQLQ improved in patients whose control of asthma improved during treatment. It had good reproducibility with no changes in scores in patients whose condition remained stable, and also high intraclass correlation coefficients for the total and domain-wise scores in these patients. Significant correlatio were found between the changes in AQLQ scores and in ACQ scores confirming the longitudinal cotruct validity. The symptoms domain score of the AQLQ was related significantly to the patient diaryrecorded scores of cough, sputum and nocturnal asthma. Cross-sectional cotruct validity of AQLQ was established by demotrating significant correlation of total, and symptoms and emotio domain scores with the ACQ scores. Conclusio. It was concluded that the AQLQ (UK English version) has sufficiently acceptable evaluative and discriminatory properties in Indian subjects and is therefore a valid itrument for quality of life measurements in clinical and research studies in asthmatics in Indian patients. Key words: Asthma, Health-related quality of life, Asthma quality of life questionnaire, Asthma control questionnaire. [Indian J Chest Dis Allied Sci 2005; 47: ] INTRODUCTION Asthma is a disease that can result in varying degrees of restriction in the physical, emotional and social spheres of a patient s life. Effectiveness of asthma treatment has traditionally been assessed by measuring the change in clinical outcome parameters such as expiratory [Received: January 21, 2004; accepted after revision: June 21, 2004] Correspondence and reprints request: Dr S.K. Chhabra, Professor and Head, Department of Cardiorespiratory Physiology, Clinical Research Centre, Vallabhbhai Patel Chest Ititute, University of Delhi, Delhi , India; Tele.: ; Telefax: ; <skchhabra@mailcity.com>.

2 168 Asthma Quality of Life S.K. Chhabra and S. Kaushik flow rates, symptoms and the need for other medicatio. It has been assumed that if one or more of these indices has improved, then the patient s health-related quality of life must have improved. This may not be true. Conversely, a patient may feel and function better, but this may not be captured by the conventional clinical outcomes. Assessment of disease-specific quality of life in clinical trials has gained widespread acceptance in the last decade because of an increased awareness of its importance as an independent outcome measure. This has been further facilitated by the development of itruments with strong measurement properties for assessing quality of life 1,2. Among the various itruments available, Juniper's Asthma Quality of Life Questionnaire (AQLQ) has been tested exteively. Several independent studies have shown that it has strong measurement properties, both as an evaluative and as a discriminative itrument 3-8. It has been tralated into various languages. Itruments to measure the asthma-specific health-related quality of life (HRQoL) have not been developed in India. Therefore, for any study on quality of life in Indian patients with asthma, the itruments available in other countries will have to be used. Quality of life is likely influenced, besides by disease severity and its treatment, by environment, personal socio-economic and cultural factors. These factors would vary from region to region and from country to country. Further, the language used in a quality of life itrument may have different meanings in different populatio. Therefore, an itrument must be validated under local conditio before it can be accepted for application in that population. In the absence of any indigenous itrument to measure quality of life, there is a need to evaluate whether the available Asthma Quality of Life Questionnaire (AQLQ) itrument is suitable for the Indian population. The present study was carried out with this aim. The UK English version of AQLQ was used, as a Hindi tralation had not been developed at the time when this study was carried out. Subjects MATERIAL AND METHODS Both male and female patients diagnosed to have bronchial asthma, in the outpatient clinic of the Clinical Research Center, Vallabhbhai Patel Chest Ititute, Delhi, were included in the study. The diagnosis was established on the basis of characteristic symptoms and demotration of reversibility of airways obstruction (post-bronchodilator increase of 200 ml and 12% over baseline in FEV 1 ) as recommended in the Expert Panel Report 9 of the National Ititutes of Health, USA. Informed coent was obtained from all the patients. The inclusion criteria was : age group years, no other concurrent pulmonary or systemic disease; relatively stable clinical state but currently symptomatic; ability to understand and respond to the English language. Patients were excluded if they had a history of smoking (>10 pack years), presence of previous lesio or history of pulmonary tuberculosis or any other respiratory disorder, any other chronic systemic disease that may affect quality of life such as diabetes, hyperteion, coronary artery disease, arthritis or were pregnant or lactating (for females), etc. Study design A detailed history was taken from all the subjects. Baseline spirometry was carried out in all the subjects. Maximum expiratory flow volume curves were obtained on a dry rollingseal spirometer (Benchmark Lung Function machine-pk Morgan, UK) according to the American Thoracic Society recommendatio for spirometry 10. The highest FVC and FEV 1 were selected. Regression equatio for lung function for Indian adults were used to calculate percent-predicted values 11. The following assessments were carried out at the time of inclusion into the study: (i) Control of asthma : The degree of control was assessed using the Asthma Control Questionnaire (ACQ) 12. The questionnaire includes questio pertaining to five symptoms

3 2005; Vol. 47 The Indian Journal of Chest Diseases & Allied Sciences 169 coidered most important for assessing asthma control. In addition there is a question on shortacting beta 2-agonist use and another on FEV 1 % predicted. Patients recalled their experiences during the previous seven days and responded to each question using a seven-point scale. The items are equally weighted and the ACQ score is the mean of the seven items and therefore between 0 (well-control) and 6 (extremely poorly controlled). (ii) Asthma quality of life questionnaire 3 (interviewer-administered version): The AQLQ has 32 questio, the first five of which are patientspecific activities. At the first visit each patient selects the five activities in which he or she has been troubled the most by asthma during the previous two weeks. These activities are retained throughout the study for subsequent tests. Patients respond to each question on a seven-point scale and recall their experiences during the previous two weeks. Results are expressed as scores for each of four domai (symptoms-12 questio, activities-11 questio, emotional function-5 questio and environmental exposure-4 questio) and as an overall score. The total and the domain scores range from 1 to 7 with higher scores indicating a better quality of life. After initial assessment and administration of the study questionnaires, the patients were prescribed appropriate treatment as per the severity of asthma 9. This coisted of inhaled corticosteroids (budesonide: µg/day or fluticasone propionate: µg/day) and if required inhaled long-acting bronchodilators (salmeterol: µg/day or formoterol: µg/day). Inhaled salbutamol (200 µg per dose, =2 puffs) was prescribed as rescue medication. All drugs advised to patients were in the form of metered dose inhalers. The patients were provided diaries to record daytime symptoms (cough, phlegm, breathlessness/wheezing), nocturnal symptoms and use of rescue medication. The scores were graded from none (0) to mild (1), moderate (2) and severe (3). The patients were assessed again at the end of four weeks when the AQLQ and ACQ questionnaires were administered. Diary scores were noted. Spirometry was repeated. Improvement in clinical state of asthma after four weeks of treatment was defined as an increase in the ACQ score of 0.5 or more 14. At the end of four weeks, patients who showed an improvement were assigned to Group A and those who showed no change in ACQ, to Group B. No patient showed a worsening. Statistical analysis Statistical analysis was carried out with the help of SPSS 11.5 and Graphpad Prism 3.0 for windows. Continuous variables were compared using unpaired/paired student s t test. Validation of the AQLQ was done by measurement of its evaluative (respoiveness and longitudinal cotruct validity) and discriminative (reproducibility and crosssectional cotruct validity) properties 16. Evaluative properties (i) Respoiveness : This is the ability of the questionnaire to detect changes in clinical status even if these are small. The respoiveness of the questionnaire was determined in two ways, firstly by comparing the scores between the patients who improved (Group A) and those who remained stable (Group B) using the unpaired t test and, secondly, by the ability of the questionnaire to detect statistically significant changes in patients who improved (Group A) using the paired t test. (ii) Longitudinal cotruct validity: Longitudinal cotruct validity was evaluated by correlating within-subject changes in quality of life scores during the four weeks observation period with within-subject changes in other indices of clinical asthma severity, i.e. ACQ scores, FEV 1 and the diary scores. Discriminative properties (i) Reliability: This is the ability of the itrument of give reproducible results when the clinical state is stable. Reliability of the itruments was determined from the data of patients who remained stable (Group B) between baseline and four weeks. The scores were compared on the two occasio (paired t test)

4 170 Asthma Quality of Life S.K. Chhabra and S. Kaushik and changes not significant were taken as an indicator of reproducibility. Further reliability analysis was carried out by calculating the intraclass correlation coefficient for total and domain scores. Intraclass correlation coefficient was calculated as a measure of agreement within cases using the reliability analysis module of SPSS 11.5 software. (ii) Cross sectional validity: It is the ability of the questionnaire to determine whether betweenpatients differences in quality of life truly reflect differences in their clinical state. Cross sectional validity was evaluated by correlating quality of life scores at baseline with other measures of asthma severity i.e. ACQ scores and FEV 1 % predicted. Patient characteristics RESULTS A total of 38 patients (21 males and 17 females) were included in the study. Thirty subjects completed the study. The reason for the eight subjects dropping out from the study was not known. Thus, data from 38 patients was used for cross-sectional cotruct validity analysis while that from 30 patients was used for analysis where two sets of data were required. The characteristics of the patients are shown in table 1. Table 1. Patient s characteristics Patient characteristics Description Age (yrs) Mean±SD 26.89±8.24 Sex (n) Males/Females 21/17 Severity of Asthma (n) Mild persistent 8 Moderate persistent 15 Severe persistent 15 Evaluative properties Respoiveness Twenty-one patients improved after treatment and were assigned to Group A. Nine patients whose control status remained unchanged were assigned to Group B. Table 2 shows the changes in AQLQ scores in the two groups. Except for the environmental domain scores, the total and other domain scores were significantly different, being higher in Group A patients, indicating an improved quality of life. All the scores showed a mean change greater than one, that represents a moderate change in the quality of life 17. Table 2. Comparison of changes in AQLQ total and domain scores in the two groups of patients AQLQ Group A Group B Total Score 1.46 ± 0.89* 0.37 ± 0.98 Symptoms 1.82 ± 1.11** 0.00 ± 1.25 Activity 1.41 ± 1.10* 0.25 ± 0.46 Emotional 1.19 ± ± 1.13 Environment 1.31 ± ± 1.51 AQLQ Domain Scores Mean ± SD : Change; *:p<0.05; **:p<0.01; +:p<0.02; :p> ** ** ** ** ** 0 wk 4 wk Total Symptoms Activity Environment Emotional Figure 1. AQLQ total and domain scores at 0 week and at four weeks in Group A patients. Figure 1 shows the AQLQ total and domain scores at 0 wk and at 4 wk in Group A patients. The scores showed a significant increase indicating an improved quality of life. The mean total score on the second visit was 5.73 ± 0.77 compared to 4.27 ± 0.78 at 0 wk (p<0.0001). Domain-wise, the scores at 0 and 4 wk were, respectively; symptoms: 4.16±0.70 and 5.99± 0.90, p<0.0001; activities: 4.23±1.01 and 5.64±0.85, p<0.0001; emotional: 4.60±0.89 and 5.80±1.05; p<0.0001; environment: 4.20±1.53 and 5.51±1.15, p< This improvement in quality of life scores in Group A was associated with an improvement in lung function indices. The FEV 1

5 2005; Vol. 47 The Indian Journal of Chest Diseases & Allied Sciences 171 improved to 2.97±0.78L on the 2nd visit compared to 2.18±0.46 on the 1st visit (p<0.0001). The FVC on the 2nd visit was 3.99±0.83L that was significantly greater than the baseline value of 3.56±0.63L (p<0.01). Longitudinal cotruct validity Longitudinal cotruct validity correlatio are shown in the table 3. There were significant correlatio between the changes in quality of life scores and the ACQ scores. However, no significant correlatio were found between the changes in quality of life scores and other indices of clinical asthma i.e. change in FEV 1 and the FEV 1 % predicted. Significant correlatio were also found between the symptoms domain of the AQLQ and the patient diary recorded scores of cough, sputum and nocturnal asthma. No correlatio were found between changes in quality of life and beta agonist use scores during the four weeks. AQLQ Domain Scores Mean ± SD wk 4wk Total Symptoms Activity Environment Emotional Figure 2. AQLQ total and domain scores at 0 week and at four weeks in Group B patients. Discriminative properties Reliability Figure 2 shows the total and domain scores of AQLQ in patients of Group B at 0 and 4 wks. The mean total score at 4 wks was 5.20±1.07 compared to 4.83 ± 0.87 at 0 wk (p>0.05). Domainwise, the scores at 0 and four weeks were, respectively; symptoms: 5.25±1.21 and 5.25±1.76, p>0.05; activities: 4.99±1.28 and 5.25±1.21, p>0.05; emotional: 5.04±1.17 and 4.75±1.49, p>0.05; environment: 3.99±1.20 and 4.61±2.16, p>0.05. The intraclass correlation coefficients for total and domain scores were as follows: total, 0.71; symptoms, 0.81; activities, 0.96; emotional, 0.79; environment, Cross-sectional cotruct validity Cross-sectional cotruct validity correlatio are shown in table 4. There were significant correlatio between total scores and the Table 3. Longitudinal cotruct validity of asthma quality of life questionnaire Symptoms Activity Emotional Environment Total FEV FEV 1 % predicted ACQ 0.631** 0.512** 0.461* ** Diary Scores Cough 0.363* Breathlessness Sputum 0.450* Nocturnal asthma 0.455* Beta-2 agonist score : Change; *:p<0.05; **:p<0.01. Table 4. Cross sectional cotruct validity of asthma quality of life questionnaire Symptoms Activity Emotional Environment Total FEV 1 % predicted ACQ 0.753** ** ** **:p<0.01.

6 172 Asthma Quality of Life S.K. Chhabra and S. Kaushik symptoms and emotio domain scores of the AQLQ and the ACQ scores. The strongest correlation was seen between the symptom domain of the AQLQ and the ACQ score. On the other hand there was no significant relatiohip with the FEV 1 % predicted. All of our patients coidered the questio in the questionnaires to be relevant to their asthmatic condition and there was apparently no difficulty in understanding of any of the questio. DISCUSSION The present study shows that UK-English version of Juniper s Asthma Quality of Life Questionnaire (AQLQ) has sufficiently acceptable evaluative and discriminatory properties for Indian asthmatic subjects and is therefore a valid itrument for quality of life measurements in clinical and research studies in asthmatics in India. In comparison to the nine stable patients, twenty-one asthmatic subjects in our study who improved on treatment showed an improvement in the AQLQ total scores and all other domai of the AQLQ except the environment domain. All the subjects who showed improvement had an increase in the mean total scores by more than one, which is suggestive of a moderate change in quality of life 16. When withiubjects changes were examined in the improved group of patients, improvement was seen in both the total scores as well as all the domai of the AQLQ. However in stable patients, there was no change in total or domain-wise quality of life scores. These observatio on the respoiveness of the AQLQ are in agreement with other studies 17. No change in quality of life scores in stable patients in our study shows that the questionnaire had good reproducibility. In longitudinal correlatio, positive relatiohips were found between changes in AQLQ and ACQ scores. The strongest correlation was found with the symptoms domain of the AQLQ (r=0.631). The symptoms domain of the AQLQ also showed significant correlatio with the diary scores of cough, expectoration and nocturnal asthma. There were no correlatio between spirometric indices i.e. FEV 1 ( = Change) and FEV 1 % predicted and total or domain-wise scores of AQLQ. The strong correlation between AQLQ scores and the ACQ scores is understandable as the ACQ evaluates the control over the past one week and the patients with good control should have better AQLQ scores and more so in the symptom domain of the AQLQ as five of the seven questio in the ACQ pertain to symptoms. The poor correlation with FEV 1 can also be explained as FEV 1 is a single measurement in time, and in the natural course of any asthmatic patient, there are swings in FEV 1. The AQLQ assesses the patient s state over the previous two weeks and thus may not correlate well with the lung function. The correlatio between changes in scores of AQLQ and the ACQ were stronger than with the diary scores. Juniper et al 3 in their previous study have reported more or less similar results. In the absence of a gold standard, validity of a questionniare may be established by showing correlatio between the questionnaire and other related outcomes (cross-sectional cotruct validity). This was done by relating the total and the domai scores of AQLQ to clinical asthma severity i.e. ACQ and FEV 1 % predicted. We found moderately significant correlatio between the ACQ and some of the domai and the total scores of AQLQ (r=0.522 to 0.753). No correlation was seen with the FEV 1 % predicted. It is known that there is a wide range of HRQoL scores for a given level of lung function 18. Degree of airways obstruction is only one of the possible determinants of quality of life. Thus, it can be argued that FEV 1 alone should not be used to define subjects into various categories of severity of asthma. As a validated Hindi version of AQLQ was not available at the time we carried out this study, the UK English version was used. Hence, knowledge of English language was one of the inclusion criteria. In India, people who are fluent in English are generally better-off economically. Therefore, extrapolating these results to all social and economic classes would be difficult. However, given its acceptable

7 2005; Vol. 47 The Indian Journal of Chest Diseases & Allied Sciences 173 discriminative and evaluative properties observed in the present study, the AQLQ needs to be studied in a wider spectrum of patients with diverse educational and economic backgrounds. A Hindi version of the AQLQ has recently been developed and such studies should be possible now. Leidy et al 19 described the AQLQ as a useful indicator of health related quality of life in low income asthmatics. To conclude, the AQLQ developed by Juniper et al 3 has acceptable evaluative and discriminatory properties for use in Indian asthmatic patients. ACKNOWLEDGEMENTS The authors wish to thank Prof. Elizabeth Juniper for her kind permission to use the UK English version of the AQLQ. REFERENCES 1. Krishner B, Guyatt GH. A methodologic framework for assessing health indices. J Chronic Dis 1985; 38: Guyatt GH, Bombardier C, Tugwell PX. Measuring disease-specific quality of life in clinical trials. Can Med Assoc J 1986; 134: Juniper EF, Guyatt GH, Ferrie PJ, Griffith LE. Measuring quality of life in asthma. Am Rev Respir Dis 1993; 147: Rutten-van Molken MPMH, Custers F, Van Doorslaer EKA, Jaen CCM, Heurman L, Maesen FPV, et al. Comparison of performance of four itruments in evaluating the effects of salmeterol on asthma quality of life. Eur Respir J 1995; 8: Rowe BH, Oxman AD. Performance of an asthma quality of life questionnaire in an outpatient setting. Am Rev Respir Dis 1993; 148: Leidy NK, Coughlin C. Psychometric performance of the asthma quality of life questionnaire in a US sample. Qual Life Res 1998; 7: Sanjuas C, Aloo J, Sanchis J, Casan P, Broquetas JM, Ferrie PJ, et al. The quality of life questionnaire with asthma patients: the Spanish version of the asthma quality of life questionnaire. Arch de Bronconeumol 1995; 31: Apter J, Reisine T, Affleck G, Barrows E, Zuwallack R. The influence of demographic and socioeconomic factors on health - related quality of life in asthma. J Allergy Clin Immunol 1999; 103: National Asthma Education and Prevention Program. Expert Panel Report Guidelines for diagnosis and management of asthma. Bethesda MD: National Ititutes of Health; 1997; Publication no American Thoracic Society: 1994 Update. Standardization of spirometry. Am J Respir Crit Care Med 1995; 152: Jain SK, Ramiah TJ. Spirometric indices in healthy men and women years age. Indian J Chest Dis 1967; 9: Juniper EF, O Byrne PM, Guyatt GH, Ferrie PJ, King DR. Development and validation of a questionnaire to measure asthma control. Eur Respir J 1999; 14: Bryne PM, Guyatt GH, Ferrie PJ, King DR, Roberts NJ. Measuring asthma control. Am J Respir Crit Care Med 2000; 162: Juniper EF, Guyatt GH, Epstein RS, Ferrie PJ, Jaeschke R, Hiller TK. Evaluation of impairment of health-related quality of life in asthma: development of a questionnaire for use in clinical trials. Thorax 1992; 47: Juniper EF, O'Byrne PM, Guyatt GH. Development and validation of the asthma control questionnaire (abstract). Am J Respir Crit Care Med 1998; 157 : A Juniper EF, Buist AS, Cox FM, Ferrie PJ, King DR. Validation of a standardized version of the asthma quality of life questionnaire. Chest 1999; 115: Juniper EF, Guyatt GH, William A, Griffith LE. Determining a minimal important change in a disease specific quality of life questionnaire. J Clin Epidemiol 1994; 47: Moy ML, Israel E, Weiss ST, Juniper EF, Dube L, Drazen JM. Clinical predictors of healthrelated quality of life depend on asthma severity. Am J Respir Crit Care Med 2001; 163: Leidy NK, Chan KS, Coughlin C. Is asthma quality of life questionnaire a useful measure for low-income asthmatics? Am J Respir Crit Care Med 1998; 158:

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