Family Practice Vol. 17, No. 4, 314-316
© Oxford University Press 2000
Lung function measurement in general practice. General practice measurements compared with laboratory measurements during the DIMCA trial
Department of General Practice and Social Medicine and
a Department of Pulmonary Diseases, University of Nijmegen (M229), PO Box 9101, 6500 HB Nijmegen, The Netherlands.
den Otter JJ, de Bruyn-Schmidt MA, Wolters MJ, van Schayck CP, Folgering HTM, van den Hoogen HJM and van Weel C. Lung function measurement in general practice. General practice measurements compared with laboratory measurements during the DIMCA trial. Family Practice 2000; 17: 314–316.
Received 14 May 1999; Revised 22 December 1999; Accepted 13 March 2000.
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Abstract |
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Background. Lung function measurement in the general practice setting (GPS) is of growing importance.
Objective.The aim of this study was to compare results from a lung function laboratory (LFL) with those in a GPS.
Methods.Comparisons were made for decline calculated from GPS and LFL measurements and intra-individual paired measurements. Test characteristics of the spirometer used in the GPS were also assessed.
Results. The mean decline in lung function was: –0.037 l/year [95% confidence interval (CI) –0.202 to 0.129] from LFL data and –0.027 l/year (95% CI –0.242 to 0.188) from GPS data. The mean intra-individual difference was –0.0025 l (95% CI –0.493 to 0.488 l). The test characteristics of the spirometer used in GPS did not meet all of the American Thoracic Society guidelines; in particular, the random error was too large. The difference in assessments between measurement in LFL and GPS were such that misclassification might occur if slopes were calculated.
Conclusions.Repeated measurement in this study showed that GPS measurements are not interchangeable with LFL measurements. Therefore, one has to be cautious when interchanging lung function data from an LFL and a GPS.
Keywords. Decline, general practice, lung function measurement.
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Introduction |
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Most guidelines for asthma and chronic obstructive pulmonary disease (COPD) stress the importance of spirometry for diagnosis and evaluation of care,1–4 with one set of guidelines2 using forced expiratory volume in l/s (FEV1) decline as a specific criterion for treatment. This implies that spirometry has to be introduced on a routine basis, to identify patients with a rapid FEV1 decline and to improve quality of care.5 However, there is concern about the accuracy of spirometry in general practice.5,6 Delegation of routine tasks7 such as spirometry to primary care staff (i.e. nurses) enhances the quality of its performance. In Dutch general practice, the practice assistant is the most likely team member to whom work such as this would be delegated.6,8 This study compares the results of spirometry in general practice and a lung function laboratory.
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Methods |
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The study compared spirometry findings in 10 general practices, collected by practice assistants, and in one lung function laboratory, collected by qualified technicians, of 128 patients. All patients had signs/symptoms of airflow obstruction, and were followed up four times a year over 2 years. Concordance of general practice and lung function laboratory spirometry was calculated from paired measurements collected within a 2-week period. Calculated individual FEV1 decline from general practice measurements was compared with that from the lung function laboratory measurement (linear regression of individual FEV1 values over 2 years).
All practices used a MicroPlus® spirometer (MP), and the laboratory used a pneumotachograph. All meters were assessed as recommended by the American Thoracic Society (ATS), for equipment9 that prescribes for diagnostic application [forced vital capacity (FVC) and FEV1] a deviation of ±3% or ±0.100 l for accuracy and of <3% or <0.100 l for precision, and for monitoring purposes (FVC and FEV1) a deviation of ±5% or ±0.100 l for accuracy and <3% or <0.100 l for precision.10 Inter-instrument variability of the 11 MP spirometers was assessed with a computer-controlled air pump connected in series with each MP.10,11
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Results |
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From the lung function laboratory measurements, an FEV1 decline of –0.037 l/year [95% confidence interval (CI) –0.202 to 0.129] was calculated, compared with –0.027 l/year (95% CI –0.242 to 0.188) from general practice measurements. With the lung function laboratory as the standard, and applying a cut-off point of 0.100 l, general practice measurements had a sensitivity of 41%, a specificity of 76%, a false-negative rate of 59%, a false-positive rate of 24%, a positive predicting value of 43% and a negative predicting value of 75%.
To assess the difference between the lung function laboratory and general practice, 135 paired measurements were available (48 subjects had more than one measurement; Table 1
).
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The assessments of the 11 MPs are shown in Table 2
. None of the meters fulfilled the criteria for peak flow and FVC. For FEV1, three meters fulfilled all criteria, and four more the criterion for systematic error.
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Discussion |
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This study points to variation in spirometry between a lung function laboratory and general practices, resulting in differences in calculated lung function decline. Several factors will play a role in these results.12 This study found technical problems with the general practice spirometers compared with the prevailing standard.10 As our spirometers were tested after 2 years of use, a decrease in quality over time11 could explain this, though others found no loss in accuracy or precision.3 The general practice spirometers functioned relatively well for FEV1 measurement, the most important measure.9 The comparison of laboratory measurement with real practice—individual paired measurements provided the wide ranges—gives some reason for concern with regard to the technical criteria.10
Because of the random variation of the spirometers, it is difficult to assess the performance of the practice assistants in the measurement. However, in all probability this must also be a factor. Unlike technicians in the lung function laboratory, practice assistants perform spirometry as one of several tasks, and their spirometer provides no flow volume curve for support.10 These factors limit their supervision.
Implementation of spirometry12 depends for its success on the technology of the spirometer and on the conditions of taking the measurement. Our data underline the need to pay adequate attention to all these factors, to prevent spirometry from contributing to unnecessary treatment or to the withholding of necessary treatment.14
When guidelines base treatment decisions on lung function decline, the quality of spirometry becomes even more important. Spirometry is the only informational basis for that decision, and inadequate measurement automatically will lead to inadequate management.14 Our results imply that guidelines recommending spirometry are not the end but rather the beginning of an important process of innovation of general practice that requires implementation.
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References |
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1 Siafakas NM, Vermeire P, Pride NB et al. Optimal assessment and management of chronic obstructive pulmonary disease (COPD). The European Respiratory Society Task Force. Eur Respir J 1995; 8: 1398–1420.[Web of Science][Medline]
2 Geijer RMM, Schayck CPv, Weel Cv et al. NHG-standaard COPD-behamdeling. Huisarts Wet 1997; 40: 430–442.
3
The British Guidelines on Asthma Management. 1995 Review and position statement. Thorax 1997; 52 (Suppl 1): S1–S21.
4 The COPD Guidelines Group of the Standards of Care Committee of the BTS. BTS guidelines for the management of chronic obstructive pulmonary disease. Thorax 1997; 52 (Suppl 5): S1–S28.
5 Hewson PH, Tipett EA, Jones DM et al. Routine pulmonary function in young adolescents with asthma in general practice. Med J Aust 1996; 165: 469–472.[Web of Science][Medline]
6 den Otter JJ, Knitel M, Akkermans RPM, van Schayck CP, Folgering HTM, van Weel C. Spirometry in general practice: the performance of practice assistants. Br J Gen Pract 1997; 47: 41–42.[Web of Science][Medline]
7 Hulscher M. Implementing prevention in general practice: a study on cardiovascular disease. 1998; 1–198 (Thesis: University of Nijmegen).
8 van Weel C. Teamwork. Lancet 1994; 344: 1276–1279.[Web of Science][Medline]
9 The American Thoracic Society. Standardization of spirometry— 1987 update. Am Rev Respir Dis 1987; 136: 1285–1298.[Web of Science][Medline]
10 The American Thoracic Society. Standardization of Spirometry—1994 update. Am J Respir Crit Care Med 1995; 152: 1107–1136.[Web of Science][Medline]
11
Nelson SB, Gardner RM, Crapo RO, Jensen RL. Performance evaluation of contemporary spirometers. Chest 1990; 97: 288–297.
12 Becklake MR, White N. Sources of variation in spirometric measurements. Identifying the signal and dealing with noise. Occup Med 1993; 8: 241–264.
13
Dirksen A, Madsen F, Pedersen OF, Vedel AM, Kok-Jensen A. Long term performance of a hand held spirometer. Thorax 1996; 51: 973–976.
14 Legge JS. Peak-expiratory-flow meters and asthma management. Lancet 1996; 347: 1709–1710.
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