Factors influencing the response to postal questionnaire surveys about respiratory symptoms.

BACKGROUND: Response rates to postal questionnaires have been falling in recent years. AIM: To examine factors affecting the response to five postal respiratory questionnaire surveys. DESIGN: Cross sectional study. SETTING: General practice. METHOD: Five surveys were conducted in all adults registered with two UK general practices using an ECRHQ-based questionnaire, with two reminders at 4-week intervals. RESULTS: Response rates declined over time (1993 - 71.2%; 1995 - 70.5%; 1999 - 65.5%; 2001 - 65.3%; 2004 - 46.9%). Age and gender of non-responders were available for 2001 and 2004: responders were older (mean 48.8 years vs 37.6, p<0.001; 50.5 vs 38.8, p<0.001) and more likely to be female (54.9% vs 44.9%, p<0.001; 55.3% vs 48.5%, p<0.001). The response rate was increased by 18% (2004) and 23% (2001) by the use of two reminders. Early responders were older and more likely to be females, but were less likely to smoke than late responders after reminders. There was no important association between respiratory symptoms and associated feature prevalence and stage of response. CONCLUSION: Declining response rates may represent reduced motivation and reluctance to share personal information. Qualitative exploration of late/non-response could help reduce bias when planning and analysing such surveys. The use of two reminders is an important factor in improving response.

Prevalence of respiratory symptoms, features of asthma, and characteristics associated with respiratory disease, in 6-11 year olds in Manchester.

AIMS: This paper describes the prevalence of respiratory symptoms, features of asthma, and characteristics associated with respiratory disease in 6-11 year old children in an historical cohort study. METHODS: The study included 5086 children, all born in the same maternity unit in the north west of England over a four-year period. The prevalence of respiratory symptoms, features of asthma, and characteristics associated with respiratory disease were determined by the use of parent-completed questionnaires. Skin prick tests were used to ascertain atopic status. RESULTS: The response was 47.5%. The prevalence of wheeze, asthma medication use and atopic sensitisation were 20.3%, 16.2% and 37.1% respectively. Wheeze and atopy were significantly more prevalent in boys (22.4% versus 17.9% and 43.0% versus 29.3%, respectively). CONCLUSIONS: This study identified a high prevalence of respiratory disease in this population and provides a baseline for monitoring trends in respiratory disease in 6-11 year old children.

Temporal change in the prevalence of respiratory symptoms and obstructive airways disease 1993-2001.

BACKGROUND: There has been little available information regarding secular changes in the prevalence of respiratory symptoms since the mid-1990s. AIM: To examine changes in the prevalence of respiratory symptoms for 1993-2001. DESIGN OF STUDY: A series of postal questionnaire surveys. SETTING: Two general practice populations, including all age groups. METHOD: Four postal respiratory questionnaire surveys were conducted between 1993 and 2001. Subjects who replied to two or more surveys (8058 adults and 2350 children) were included in the main analyses. Validated scoring systems were used to define obstructive airways disease in adults and asthma in children. RESULTS: Over the 8-year observation period there were increases among adults in the crude prevalence of wheeze, being woken by cough, receipt of current asthma medication, and of obstructive airways disease, compared with decreases in children for wheeze, night cough, asthma attacks, and asthma. For adults, adjusted odds ratios per year of secular increase were 1.03 (95% confidence interval [CI] = 1.02 to 1.03) for wheeze, 1.03 (95% CI = 1.02 to 1.03) for being woken by cough, 1.03 (95% CI = 1.02 to 1.04) for asthma medication, and 1.02 (95% CI = 1.01 to 1.03) for obstructive airways disease. These increases were greater in those aged over 44 years, in males, and in those without a family history of asthma or a history of hayfever or eczema. Corresponding decreases for children were 0.94 (95% CI = 0.92 to 0.97) for wheeze, 0.93 (95% CI = 0.91 to 0.96) for night cough, 0.93 (95% CI = 0.90 to 0.95) for asthma attacks and 0.98 (95% CI = 0.95 to 1.00) for asthma. CONCLUSION: The increases found in adults are more likely to be due to chronic obstructive pulmonary disease (COPD) than asthma. This is supported by the decreases in symptom and asthma prevalence in children.

Childhood asthma: healthcare resource utilisation in those with and without a diagnosis of the condition.

AIM: To examine healthcare utilisation and the direct financial costs in providing medical care to a population of children aged 5-15 years with respiratory complaints. Secondarily, to assess whether these costs depended upon having specific asthma diagnosis or not. METHOD: A postal respiratory questionnaire was sent to the parents or guardians of all children registered with two general practices. A search of the general practice medical records over a 2-year reference period was made for a stratified random sample and results are presented for 488 children aged 5-15 years. RESULTS: The cost of primary care lower respiratory tract consultations in children with 4-5 symptoms/risk factors was pounds sterling 17.02 per patient per year for those with a previous diagnosis of asthma compared with pounds sterling 6.08 per patient per year for those with the same number of symptoms but no diagnosis (t = -4.446, P<0.001). The cost of primary care lower respiratory consultations in those with no GP diagnosis of asthma and no symptoms/risk factors was pounds sterling 2.25 per patient per year. CONCLUSIONS: Studies, which fail to include the costs associated with treating children with respiratory symptoms but without a formal diagnosis, will seriously underestimate the costs of treating asthmatic children.

Development of a questionnaire weighted scoring system to target diagnostic examinations for asthma in adults: a modelling study.

BACKGROUND: Identification and treatment of unrecognised asthmatics in the community is important for improving the health of the individual and minimising cost and quality of life burden. It is not practical to offer clinical diagnostic assessment to whole communities, and a simple tool such as a questionnaire is required to identify a smaller target group. Conventional questionnaire screening methods which separate individuals into positive and negative categories have resulted in large numbers of individuals requiring clinical assessment. This study has therefore developed and tested a weighted scoring system that prioritises those most urgently in need, based on their questionnaire responses. METHODS: A stratified random sample of adult respondents to a general practice postal questionnaire survey were categorised 'asthmatic' or 'non-asthmatic' according to three expert physicians' opinions. Based on this categorisation, logistic regression was used to derive weights reflecting the relative importance of each question in predicting asthma, allowing calculation of weighted scores reflecting likelihood of asthma. Respondents scoring higher than a chosen threshold would be offered diagnostic examination. RESULTS: Age and presence of wheeze were most influential (weight 3) and overall weighted scores ranged from -1 to 13. Positive predictive values (PPV) were estimated. For example, setting the threshold score at nine gave an estimated PPV for asthma diagnosis of 93.5%, a threshold score of seven corresponded to PPV 78.8%. PPV estimates were supported by examining 145 individuals from a new survey. CONCLUSION: Weighted scoring of questionnaire responses provides a method for evaluating the priority level of an individual 'at a glance', minimising the resource wastage of examining false positives.

Identification of adults with symptoms suggestive of obstructive airways disease: validation of a postal respiratory questionnaire.

BACKGROUND: Two simples scoring systems for a self-completed postal respiratory questionnaire were developed to identify adults who may have obstructive airways disease. The objective of this study was to validate these scoring systems. METHOD: A two-stage design was used. All adults in two practice populations were sent the questionnaire and a stratified random sample of respondents was selected to undergo full clinical evaluation. Three respiratory physicians reviewed the results of each evaluation. A majority decision was reached as to whether the subject merited a trial of obstructive airways disease medication. This clinical decision was compared with two scoring systems based on the questionnaire in order to determine their positive predictive value, sensitivity and specificity. RESULTS: The PPV (positive predictive value) of the first scoring system was 75.1% (95% CI 68.6-82.3), whilst that of the second system was 82.3% (95% CI 75.9-89.2). The more stringent second system had the greater specificity, 97.1% (95% CI 96.0-98.2) versus 95.3% (95% CI 94.0-96.7), but poorer sensitivity 46.9% (95% CI 33.0-66.8) versus 50.3% (95% CI 35.3-71.6). CONCLUSION: This scoring system based on the number of symptoms/risk factors reported via a postal questionnaire could be used to identify adults who would benefit from a trial of treatment for obstructive airways disease.

The Impact of Respiratory Symptoms on Healthcare Utilisation: The Primary and Secondary Care Interface.

BACKGROUND: There is evidence that the prevalence of asthma is increasing but little is known about the contribution made by respiratory illness to the combined workload of primary and secondary healthcare. AIM: To examine the relationship between self-reported respiratory symptoms in adults and health care utilisation. METHODS: Two general practice populations received a postal questionnaire regarding respiratory symptoms in 1993. A random sample of 736 adult respondents was stratified according to number of positive responses to six key questions (to indicate likelihood of asthma diagnosis). Their records were searched for utilisation of healthcare services, to include both primary and secondary sectors. RESULTS: Positive responses to the key questions were associated with increased relative risk of having a GP consultation, home visit, investigation and prescription issued for lower respiratory problems. Those with higher numbers of positive responses had increased relative risk of out-patient or A & E attendance as well as in-patient admission. CONCLUSION: The principal finding of this study is that respiratory symptoms are significantly positively associated with utilisation of health care services for lower and upper respiratory problems. This study provides quantitative evidence of the interface between primary and secondary care in two general practice populations. It provides a method for predicting health care utilisation in both primary and secondary sectors based on reported respiratory symptoms.

Temporal change in health-related quality of life: a longitudinal study in general practice 1999-2004.

BACKGROUND: In order to assess and plan for changing healthcare needs, the lack of available information regarding temporal changes in the health-related quality of life of a population must be addressed. AIM: This paper aims to describe such changes over 5 years in a general population. DESIGN OF STUDY: Longitudinal postal questionnaire study. SETTING: UK general practice. METHOD: This was a longitudinal postal questionnaire study in two general practice populations, using the generic instrument EQ-5D to measure health-related quality of life. Individuals were included if they responded to three postal surveys in 1999, 2001, and 2004 and there were three consecutive values of EQ-5D(index) available between 1999 and 2004. RESULTS: A total of 2498 subjects were included in the study. After adjustment for potential confounders (including ageing), health-related quality of life declined significantly over the observation period. The change in EQ-5D(index) was from 0.79 to 0.74 and for EQ-5D(vas) 76.8 to 73.3 (P for both trends <0.001). CONCLUSION: Health-related quality of life deteriorated in these populations over 5 years. In an era of improvements in mortality, this has important implications for the use of health-related quality of life data in healthcare planning and resource allocation.

How do common chronic conditions affect health-related quality of life?

BACKGROUND: Comorbidity is common. National Institute for Health and Clinical Excellence (NICE) guidelines have been created to make best use of resources to improve patients' quality of life but do not currently take account of comorbidity. The effect of multiple chronic conditions with regard to health-related quality of life (HRQoL) is poorly researched. Criticisms of previous research have been due to patient-defined chronic conditions, lack of quantification of the effects of confounding factors, selection of affected patients only, small sample sizes, and upper age limits. AIM: This study aims to address these issues, looking into the impact of combinations of chronic conditions on HRQoL. DESIGN OF THE STUDY: Participants filled in a questionnaire containing general health information, specific respiratory questions, and the EQ-5D measure of HRQoL. The questionnaires were then matched up to their GP records to obtain their disease status for six common chronic diseases (asthma, chronic obstructive pulmonary disease, ischaemic heart disease, hypertension, diabetes, and cerebrovascular disease). METHOD: Data from a mailed questionnaire were analysed from 5169 patients aged >16 years from two general practices in Wythenshawe, Manchester in 2004. Completion of the questionnaire was taken to indicate consent to participate. RESULTS: Significant correlations were found between a lower HRQoL and increasing numbers of chronic conditions (P<0.001), increasing age, possible obstructive airway disease, lack of higher education, smoking, and female sex. These all remained significant following regression, except for sex, with number of chronic conditions being a strong predictor of the weighted health state index score, EQ-5D(index) (coefficient = -0.079, P<0.001). CONCLUSION: Increasing numbers of chronic conditions have a strong negative effect on HRQoL.

Prevalence of airflow obstruction in patients attending a rapid access chest pain clinic.

BACKGROUND: Many UK hospitals have set-up specialised chest pain clinics to deal promptly and efficiently with cases of possible cardiac chest pain. It is possible that a proportion of patients attending these clinics will have a respiratory cause for their chest pain, or respiratory disease in addition to their cardiac pain. This study aimed to determine the prevalence of airflow obstruction, ischaemic heart disease and dual pathology in such patients. METHODS: Spirometry was performed on patients referred to a rapid access chest pain clinic over a 12-month period (target population of 400 patients). The main outcome measure was the prevalence of airflow obstruction (defined using spirometry), ischaemic heart disease and dual pathology. RESULTS: 405 subjects participated in the study. Abnormal spirometry was detected in 21% of patients (n=85). Airflow obstruction was the predominant lung function abnormality and was detected in 60 patients. Ischaemic heart disease was diagnosed in 21% of patients (n=85). Dual pathology was found in 4% of patients (n=17). CONCLUSIONS: Previous studies have reported a link between impaired lung function and future cardiovascular morbidity and mortality. This study suggests that airflow obstruction is an important alternative differential diagnosis in patients referred to a rapid access chest pain clinic. The identification of abnormal spirometry may help to better risk-stratify patients for future cardiovascular events and allow interventions to be instituted.

Long term prognosis in preschool children with wheeze: longitudinal postal questionnaire study 1993-2004.

OBJECTIVES: To follow a population of preschool children with and without parent reported wheeze over a period of 6-11 years to determine prognosis and its important predictive factors. DESIGN: Longitudinal series of five postal surveys based on the international study of asthma and allergies in childhood questionnaire carried out between 1993 and 2004. SETTING: Two general practice populations, south Manchester. PARTICIPANTS: 628 children aged less than 5 years at recruitment and those with at least six years' follow-up data. MAIN OUTCOME MEASURES: Parent completed questionnaire data for respiratory symptoms and associated features. RESULTS: Of 628 children included in the study, 201 (32%) had parent reported wheeze at the first observation (baseline), of whom 27% also reported the symptom on the second occasion (persistent asthma). The only important baseline predictors of persistent asthma were exercise induced wheeze (odds ratio 3.94, 95% confidence interval 1.72 to 9.00) and a history of atopic disorders (4.44, 1.94 to 10.13). The presence of both predictors indicated a likelihood of 53.2% of developing asthma; if only one feature was present this decreased to 17.2%, whereas if neither was present the likelihood was 10.9%. Family history of asthma was not predictive of persistent asthma among children with preschool wheeze. CONCLUSION: Using two simple predictive factors (baseline parent reported exercise induced wheeze and a history of atopic disorders), it is possible to estimate the likelihood of future asthma in children presenting with preschool wheeze. The absence of baseline exercise induced wheeze and a history of atopic disorders reduces the likelihood of subsequent asthma by a factor of five.

The estimated prevalence of chronic obstructive pulmonary disease in a general practice population.

OBJECTIVE: To estimate the prevalence of chronic obstructive pulmonary disease (COPD) in a general practice population in the UK. METHOD: Four postal respiratory questionnaire surveys were carried out between 1993 and 2001. Subjects from the 2001 study were invited for spirometry if they were aged 30 years or more, had indicated that they were 'ever smokers' in any of the surveys, and/or had been considered to have likely obstructive airways disease on the basis of their replies to the 2001 questionnaire. RESULTS: 2646 subjects were invited for spirometry of whom 871 (32.9%) attended. Results were available for 825 participants. 163 of these subjects were categorised as having COPD. The estimated prevalence in the whole population was 4.1% with the highest prevalence (14.7%) in those aged 60-69 years. In those aged over 40 years it was 9.6%. CONCLUSION: This study suggests that the prevalence of COPD is much higher than the previous estimates of between 1 and 2%.

Is the prevalence of wheeze in children altered by neonatal BCG vaccination?

BACKGROUND: The prevalence of asthma and atopic disease has increased in recent decades, but precise reasons for this increase are unknown. BCG vaccination is thought to be among a group of vaccines capable of manipulating the immune system toward T(H)1 dominance and therefore reducing the likelihood of atopic disease. OBJECTIVE: The aim of this study was to determine the influence of neonatal BCG vaccination on the prevalence of wheeze in a large community population of children. METHOD: In a historical cohort study, a parent-completed questionnaire was used to identify the prevalence of wheeze in BCG-vaccinated and nonvaccinated children in Manchester, England. RESULTS: There were 2414 participants aged between 6 and 11 years. In a univariate analysis neonatal BCG vaccination was associated with a significantly lower prevalence of wheeze (odds ratio, 0.69; 95% CI, 0.55-0.86), and statistical significance was retained when the analysis was adjusted for potential confounders (odds ratio, 0.68; 95% CI, 0.53-0.87). CONCLUSION: These results demonstrate an association between asthma symptom prevalence and neonatal BCG vaccination, relating to a possible 27% reduction in prevalence, and are therefore of considerable public health importance. CLINICAL IMPLICATIONS: The capacity of neonatal BCG vaccination to reduce the prevalence of respiratory symptoms in children warrants further investigation.

The diagnostic accuracies of chronic obstructive pulmonary disease (COPD) in general practice: The results of the MAGIC (Manchester Airways Group Identifying COPD) study.

BACKGROUND: Although it is generally accepted that chronic obstructive pulmonary disease (COPD) is underdiagnosed, there is little objective information concerning the size of the problem in the UK. METHOD: Patients from two general practices were offered spirometry if they were aged 30 or older, had reported ever smoking in one of four postal respiratory surveys (1993-2001), and/or reported four or more symptoms or risk factors in 2001 indicating likely obstructive airways disease. RESULTS: Of 2646 subjects invited, 871 attended and 825 had adequate spirometry results for analysis. In all, 163 patients had spirometrically-confirmed COPD; 103 of these (63.2%) had no recorded COPD in their practice records, including 14 out of 31 (45.2%) whose spirometry results classified them as having severe or very severe COPD. CONCLUSION: This study found a considerable under-recording of COPD in two general practices. This may be due to a combination of administrative and diagnostic problems (including the under-use of spirometers), and a reluctance of patients to present with their symptoms. These results have important implications in terms of unmet need and resource utilisation.