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TRJ Schermer, AJ Crockett, PJP Poels, et al
Advance online publication
Quality of routine spirometry tests
in Dutch general practices
Tjard RJ Schermer, Alan J Crockett, Patrick JP Poels, Jacob J van Dijke, Reinier P Akkermans, Hans F Vlek and Willem R Pieters INTRODUCTION
ABSTRACT
Spirometry is currently being promoted as an Background
indispensable tool for primary care doctors and Spirometry is an indispensable tool for diagnosis and nurses to diagnose and monitor chronic airways monitoring of chronic airways disease in primary care.
disease.1,2 Several previous studies indicate that primary care spirometry increases rates of diagnosis To establish the quality of routine spirometry tests in for chronic respiratory disease and may also lead to general practice, and explore associations betweentest quality and patient characteristics.
improvements in its treatment.3–5 However, good- Design of study
quality spirometry requires comprehensive training of Analysis of routine spirometry test records.
staff, reliable equipment, and well-standardised measurement procedures.6 This may be difficult to Fifteen general practices which had a working achieve in primary care practice, especially when agreement with a local hospital pulmonary function tests are rather infrequently administered, which laboratory for spirometry assessment regarding testquality and interpretation.
appears to be the case in most practices.7 In a previous study by the current authors it was Spirometry tests were judged by a pulmonary function observed that the most relevant spirometric indices, technician and a chest physician. Proportions of testadequacy were analysed using markers for manoeuvreacceptability and test reproducibility derived from the1994 American Thoracic Society spirometry guideline.
TRJ Schermer, MSc, PhD, senior researcher, Department of
Associations between quality markers and age, sex, Primary and Community Care, Asthma and COPD Research and severity of obstruction were examined using Unit, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands, and Primary Care Respiratory Research Unit, Discipline of General Practice, School of Population Health and Practices performed a mean of four (standard deviation Clinical Practice, University of Adelaide, Australia. AJ Crockett,
= 2) spirometry tests per week; 1271 tests from 1091 PhD, associate professor, Primary Care Respiratory Research adult patients were analysed; 96.4% (95% confidence Unit, Discipline of General Practice, School of Population interval [CI] = 95.6 to 97.2) of all tests consisted of ≥3 Health and Clinical Practice, University of Adelaide, Australia. blows. With 60.6% of tests, forced expiratory time was PJP Poels, MD, PhD, GP; RP Akkermans, MSc, statistician,
the marker with the lowest acceptability rate. An overall Department of Primary and Community Care, Asthma and 38.8% (95% CI = 36.0 to 41.6) of the tests met theacceptability as well as reproducibility criteria. Age, COPD Research Unit, Radboud University Nijmegen Medical sex, and severity of obstruction were associated with Centre, Nijmegen and General Practice Bles and Poels, Huissen, The Netherlands. JJ van Dijke, MD, GP, General Practice Van
Dijke, Westervoort, The Netherlands. HF Vlek, MD, PhD,
Conclusion
Quartz Transmural Centre, Helmond, The Netherlands. The quality of routine spirometry tests was better thanin previous reports from primary care research settings, WR Pieters, MD, chest physician, Department of Pulmonary
but there is still substantial room for improvement.
Medicine, Elkerliek Hospital, Helmond, The Netherlands. Sufficient duration of forced expiratory time is the Address for correspondence
quality marker with the highest rate of inadequacy.
Primary care professionals should be aware of patient Tjard RJ Schermer, Radboud University Nijmegen Medical characteristics that may diminish the quality of their Centre, Department of Primary and Community Care (117- spirometry tests. Further research is needed to ELG), PO Box 9101, 6500 HB Nijmegen, The Netherlands.
establish to what extent spirometry tests that are inadequate, according to stringent international expertcriteria, result in incorrect clinical interpretations in Submitted: 12 September 2008; Editor’s response: 29
December 2008; final acceptance: 18 March 2009.
Keywords
British Journal of General Practice diagnosis; family practice; lung diseases, obstructive;quality of health care; spirometry.
Cite this article as: Br J Gen Pract Advance online publication.
4 Nov 2009; DOI: 10.3399/bjgp09X473088.
British Journal of General Practice, Advance online publication 2009
Original Papers
as measured by trained general practice staff, were comparable to those measured in pulmonary How this fits in
investigators from New Zealand demonstrated a Spirometry is an indispensable tool for primary care doctors and nurses to significant effect of spirometry workshops on test diagnose and monitor chronic airways disease. Good-quality spirometry requires comprehensive training of staff, reliable equipment, and well-standardised quality, but concluded that the spirometry performed measurement procedures, which may be difficult to achieve in a general practice.
in primary care practices did not generally satisfy the In this study, the quality of routine spirometry tests was better than in previous full criteria for acceptability and reproducibility.9 One reports from primary care research settings, but there is still substantial room for feature that these two studies have in common is improvement. Sufficient duration of forced expiratory time is the quality marker that they were both conducted as research with the highest rate of inadequacy. Primary care professionals should be aware exercises. Because of this, the findings may not of patient characteristics that may diminish the quality of their spirometry tests.
provide a reflection of the actual quality of spirometry as performed in usual primary care practice.
In an attempt to arrange good-quality primary care postbronchodilator test) that had been submitted spirometry, 15 general practices in the region by GPs from March 2003 to August 2005. Each of surrounding the Elkerliek general hospital in the city the 15 general practices involved owns a PC-based of Helmond, the Netherlands have established a spirometer and software (SpiroPerfect™, Welch working agreement with the hospital regarding the Allyn, Delft, the Netherlands). The hospital’s support of spirometry training, interpretation, and pulmonary laboratory service has direct access to performance. Practices can request on-site technical the tests submitted by GPs. Spirometry training and support and supervision by a technician from the support has been offered to GPs (with a focus on hospital’s pulmonary laboratory service. The current test interpretation), practice nurses, and practice study aimed to establish the quality of routine assistants (with a focus on performing tests) once general practice spirometry tests within this ‘real-life’ or twice a year since the late 1990s.
setting. In addition, it explored whether in this After online submission of results to the central particular setting the quality of spirometry tests is database, the quality of spirometry tests is first associated with patients’ sex and age, and the judged by a pulmonary function technician. Based on the 1994 American Thoracic Society spirometry guideline,6 several spirometry quality markers were derived for every test submitted by the general Setting and spirometry tests
practices. (It was decided not to use the more recent Using a central database, analysis was carried out 2005 guideline10 because it had not yet been of all routine care spirometry tests (either a published at the time when the spirometry tests were prebronchodilator test alone or a full reversibility performed.) Box 1 shows the test quality markers as test consisting of a prebronchodilator and a extracted from the 1994 American Thoracic Society Box 1. Markers of spirometry test quality as derived from the 1994 American
Thoracic Society spirometry guideline.6
Ǡ Markers for acceptability of separate blows Flow–volume curve shows steep initial incline Flow–volume curve shows uninterrupted forced expiration Forced expiration of reasonable durationa <5% of FVC or 0.15 litre, whichever is greater Volume–time curve shows an obvious plateaub FVC = forced vital capacity. FEV1 = forced expiratory volume in 1 second. aFor patients with airways obstruction or olderpatients, exhalation times longer than 6 seconds are frequently needed to reach a plateau. bNo change in volume for at least1 second after an exhalation time of at least 6 seconds. cDifference between highest and second highest values of the twomanoeuvres with the highest sum of FEV1 and FVC. British Journal of General Practice, Advance online publication 2009
TRJ Schermer, AJ Crockett, PJP Poels, et al
one of the hospital’s chest physicians, who records the presence and/or severity of airflow obstruction, reversibility after bronchodilation, and a possible restrictive pattern. The combined results of the quality assessment and the diagnostic assessment of each test are reported back to the general Statistical analysis
For repeated measurements, the same patient could contribute multiple spirometry tests. For the analysis of spirometry test quality, only the prebronchodilator tests of patients aged ≥12 years were used. After analysis of the test quality markers for the total study population, 675 patients (62%) could be stratified according to the severity of their airflow obstruction as judged by a chest physician. When the chest physician had judged that obstruction was present but had not indicated the severity (12% of all patients with obstruction), the cut-off values from the Global Initiative for Chronic Obstructive Lung Disease guideline11 were used to categorise severity: forced expiratory volume in 1 second (FEV1) % predicted >80% for mild; 50–80% for moderate; and <50% for severe and very severe obstruction. European Coal and Steel Community reference equations were used Figure 1. Examples of
spirometry guideline, and for each marker whether or characteristics were compared between severity unacceptable spirometry
not it could be included in the study analysis of subgroups using χ2 tests and analysis of variance.
test quality markers as
general practice spirometry test quality. Figure 1 Multivariable logistic regression analysis was used to read from the
shows examples of unacceptable blows for markers explore associations between spirometry test quality flow–volume curve.
that can be judged from the flow–volume curve. After markers and sex, age, and severity of obstruction.
The odds ratio (OR) estimates from the logistic assessment, each test is diagnostically assessed by regression models express the (adjusted) risk for an inadequate test quality marker to be present.
Table 1. Characteristics of the study population (n = 1091)
Statistical tests were two-sided, and P<0.05 was and the subgroup identified with airflow obstruction as
considered statistically significant.
judged by a chest physician (n = 675).a
General practices
Spirometry tests had been submitted by all 15 general practices comprising 49 GPs (mean number of GPs per practice = 3.3, range = 1–5). Two practices (13%) had implemented spirometry <1 year ago, three practices for 1–2 years ago, and the remaining practices ≥2 years ago. A mean of four spirometry tests (standard deviation [SD] = 2) were performed per week. Spirometry was administered by a practice assistant in 12 practices, by a practice nurse in six practices, and by a GP in two practices (in some practices, more than one type of healthcare professional administered spirometry).
aFigures are means (SD) unless stated otherwise. bTest for differences between subgroupsbased on severity of airflow obstruction. cIncluding very severe obstruction. dBased on first Patients
postbronchodilator measurement available in the database for each patient. FEV1 = forced Mean age of the study population (n = 1091) was expiratory volume in 1 second; FVC = forced vital capacity. 53.4 (SD 16.9) years (Table 1), and mean FEV1 % British Journal of General Practice, Advance online publication 2009
Original Papers
predicted was 82.5% (SD 21.0%); 143 patients Table 2. Quality assurance data from
(13.1%) contributed two spirometry tests to the 1271 prebronchodilator spirometry
database on two different dates, 18 patients (1.7%) tests from the 15 general practices
contributed three or more tests. Bronchodilator involved in the study.
reversibility testing was performed in 92.5% of all the Indications for spirometry as reported by the GPs were: (re)assessment of previous diagnosis of chronic airways disease, including tests to assess possible exacerbations (42%); diagnostic assessment without prior diagnosis of chronic airways disease (35%); periodic monitoring of lung function (13%); evaluation of diagnostic prednisolone test (6%); and screening tests with one or more markers that indicated Acceptability and reproducibility of
unacceptability, females showed a higher risk of test spirometry tests
unacceptability (OR = 1.67, 95% CI = 1.23 to 2.35; A total of 1271 prebronchodilator tests comprising 3968 forced expiratory manoeuvres (blows) were available for analysis. Mean number of blows per test DISCUSSION
was 3.1 (range = 1–9) and 97.8% (95% confidence Summary of main findings
interval [CI] = 97.0 to 98.6) of all tests consisted of This study aimed to establish the quality of general three or more blows; 38.8% (95% CI = 36.0 to 41.6) practice spirometry tests outside a typical research of the tests met the acceptability as well as the setting, and explored whether spirometry test quality reproducibility criteria (Table 2). The proportion of was associated with patients’ sex and age, and the tests that met all five assessed acceptability markers presence of obstruction in patients tested in general was 43.3% (95% CI = 40.2 to 45.8; Table 3).
practice. It was found that 39% of all tests performed In 37.6% of all tests, one marker was judged by in the general practices met the combined set of acceptability and reproducibility markers as derived unacceptable, two markers in 11.4%, three markers from the 1994 American Thoracic Society spirometry in 5.2%, and four or five markers in 2.5%. With guideline. Too short forced expiratory time was the 60.6%, forced expiratory time was the marker with marker with the lowest rate of acceptability (60.6%).
the lowest rate of acceptability. The average forced Several associations were observed between test expiratory time was 7.6 seconds (SD 3.9 seconds).
acceptability markers and sex, age, and presence or Adequacy of the other acceptability markers ranged from 80.5% for duration of the forced expiration to 92.7% for steep initial incline of the flow–volume Strengths and limitations of the study
Particular strengths of this study are that all the tests in the spirometry database were obtained from Associations between acceptability markers
‘regular’ (that is, non-academic) general practices, and patient characteristics
and that they were performed as a part of routine testing in daily patient care. Compared to Dutch associated with one or more of the acceptability national figures, the general practices in the present markers (Table 4). Compared with males, females had a higher ‘risk’ of unacceptable blows for two Table 3. Results of overall assessment of acceptability
markers for 1271 general practice spirometry tests
markers, that is, duration of forced expiration (OR = comprising 3968 forced expiratory manoeuvres.
1.57, 95% CI = 1.15 to 2.14) and initial incline to peak flow (OR = 3.00, 95% CI = 1.50 to 6.00). In one or more of the older age groups, the risk of an Flow–volume curve shows steep initial inclinea unacceptable marker increased for initial incline to peak flow, sharpness of peak, and course of forced Flow–volume curve shows uninterrupted expirationa expiration. The presence of obstruction showed an Forced expiration of reasonable durationa inverse relationship with the initial incline to peak flow, sharpness of peak, course of forced expiration, and duration of the forced expiration (Table 4). When aAccording to judgement of pulmonary function technician. the fully acceptable tests were offset against the British Journal of General Practice, Advance online publication 2009
TRJ Schermer, AJ Crockett, PJP Poels, et al
contribute to the current knowledge regarding Table 4. Results of multivariable logistic regression analyses
for associations between markers of forced expiratory
spirometry test quality in primary care, and identify manoeuvre acceptability and sex, age, and degree of
points of impact for quality improvement.
airflow obstruction as established by a chest physician.
Comparison with existing literature
Too short forced expiratory times and early Initial steep incline of flow–volume curve previously been recognised as one of the main deficiencies of spirometry in general,15,16 and of primary care spirometry in particular.9,17 In this study, spirometry acceptability markers and both presence of airflow obstruction and older age. An association between older age and worse spirometry test performance has been reported previously, and is likely to be explained by cognitive impairment in older people.9,18–20 Contrary to previous reports in which male sex was associated with poorer reproducibility of FEV1,19 the present study showed Uninterrupted course of expiratory part of flow–volume curve an association of female sex with test inadequacy for two acceptability markers: forced expiratory time and initial incline to peak flow. The explanation may be that females feel more embarrassed than males while performing forced expiratory manoeuvres because of the possibility of leaking urine.13 Differences between previous studies and the Duration of forced expiration ≥6 seconds present observations may be caused by several factors. Different levels of spirometry training among the primary care professionals who administer the tests is certainly one of these factors.7 The achievements of the general practices in the current study contrast with those previously reported from a New Zealand study, which showed far more dramatic results: 3–13% percent of all tests were acceptable and reproducible, with almost the same set of criteria A comparison with the studies reported from pulmonary function laboratories shows that in research as well as in routine care the proportion of reproducible tests is generally at least 90% Odds ratio (OR) expresses the risk of an inadequate test quality marker compared to the (Appendix 1). It is doubtful whether primary care reference category. Statistically significant associations (P<0.05) are printed bold. aMales as professionals will ever be able to approach this reference category. bAge <50 years as reference category. cNo obstruction as referencecategory. performance level. Apart from limited training and quality assurance activities, lack of experience and study were mostly group practices with three or more routine are likely to be important factors in the high GPs (56% versus 13% nationally), had slightly less rate of low-quality spirometry tests observed in experience with spirometry (6 versus 7 years), and general practice.7,21 On the other hand, it is currently performed a similar number of spirometry tests per unclear what the actual impact of inadequate month (16 versus 17 tests/month).13,14 A weakness of the study may be that all practices involved in the evaluation participated in the working agreement previously demonstrated that, compared with with the local hospital, which may limit the external validity of the findings; it is not possible to tell from laboratories in the same patients, FEV1 and forced this study how practices that have no expert support vital capacity as measured by trained general practice staff do not necessarily result in differences Despite these shortcomings, the present findings that are relevant in general practice.22 This suggests British Journal of General Practice, Advance online publication 2009
Original Papers
that an important proportion of spirometry tests that Discuss this article
Contribute and read comments about this article on theDiscussion Forum: http://www.rcgp.org.uk/bjgp-discuss stringent international test criteria6,10 may still provide the GP with useful results on which to base REFERENCES
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Appendix 1. Proportions of adequate spirometry tests with regard to forced expiratory volume in
1 second (FEV1) and forced vital capacity (FVC) reproducibility criteria in published primary care studies.
Public schools students aged 9–18 years Patients ≥65 years attending one of the 24 1622 involved pulmonary or geriatric institutions Studies conducted in pulmonary function laboratories are included as points of reference. Studies have used different definitions for reproducibility, which limitsdirect comparison of results.32 Definitions used in the respective studies are: ITwo highest FEV1 values <5% and <200 ml; IILargest FEV1 values and largest FVC values ≤200 ml; IIITwo highestFEV1 values and FVC values ≤5%; IVDifference between highest and second-highest FEV1 <150 mL; VFVC and FEV1 values at least 95% of the largest values;VIDifference between highest and second-highest value <200ml for FEV1 and FVC; VIIDifference between highest and second-highest FVC <200ml. aReproducibility results not reported for FEV1 and FVC separately. bFor pre- and postbronchodilator tests respectively. cFor usual and trained practicesrespectively. dReproducibility calculated without prior selection of acceptable blows according to 1994 American Thoracic Society spirometry guidelines.6 COPD = chronic obstructive pulmonary disease. British Journal of General Practice, Advance online publication 2009

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