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(Chest. 2005;128:2443-2447.)
© 2005 American College of Chest Physicians

Spirometry in the Primary Care Setting*

Influence on Clinical Diagnosis and Management of Airflow Obstruction

Robert E. Dales, MD; Katherine L. Vandemheen, BSc; Jennifer Clinch, MSc and Shawn D. Aaron, MD

* From the Department of Medicine (Dr. Dales), University of Ottawa; and Clinical Epidemiology Unit (Ms. Vandemheem, Ms. Clinch, and Dr. Aaron), Ottawa Health Research Institute, Ottawa, ON, Canada.

Correspondence to: Robert Dales, MD, Division of Respirology, The Ottawa Hospital (General Campus), 501 Smyth Rd, Box 211, Ottawa, ON K1H 8L6, Canada; e-mail: rdales{at}ohri.ca


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Study objective: To determine if screening spirometry in the primary care setting influences the physician’s diagnosis and management of obstructive lung disease.

Design: Diagnosis and management assessed before and after the intervention of screening spirometry.

Participants: A total of 1,034 patients who had ever smoked and were at least 35 years of age presenting to primary care practices for any reason.

Setting: Rural primary care practices.

Measurements and results: Physicians were asked prior to and following presentation of spirometry test results if they thought airflow obstruction was present and if they planned to change management based on the results. A new diagnosis of unsuspected airflow obstruction was made by the physician in 93 patients (9%), and a prior diagnosis of airflow obstruction was removed after spirometry in 115 patients (11%). After viewing the spirometry results, physicians reported that they would change patient management in 154 patients (15%). Most planned management changes occurred when airflow obstruction was newly diagnosed (57 of 93 patients, 61%) and when the diagnosis of airflow obstruction remained unchanged (80 of 195 patients, 41%). A 6-month chart review documented the addition of respiratory medications in 8% of patients.

Conclusion: Screening spirometry influences physicians’ diagnosis of airflow obstruction and management plans especially in patients with moderate-to-severe obstruction.

Key Words: asthma • COPD • obstructive lung disease • spirometry


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
It is believed that spirometry, the "gold standard" for diagnosing airflow obstruction, is underutilized in clinical practice.1 The National Lung Health Education Program has recommended "the widespread use of office spirometry by primary-care providers for patients 45 years or older who smoke cigarettes."1 However, the usefulness of spirometry in the primary care setting has still not been carefully examined. Although previous studies23 have partially addressed the ability of spirometry to diagnose airflow obstruction in the community setting, there are no studies that have assessed whether the introduction of spirometry to a primary practice setting will influence patient management.

To address this question, we introduced spirometry into primary care practices and determined the proportion of patients in whom diagnosis or proposed management plans were changed. The hypothesis was that there would be both underdiagnosis and possibly misdiagnosis of airflow obstruction in the practices prior to the introduction of spirometry. We further hypothesized that the introduction of spirometry would influence physician management, especially for those patients with airflow obstruction that was unsuspected, severe, and symptomatic.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Geographic Location
Primary care practices were recruited from rural Eastern Ontario, Canada. The practices had to be within a 2-h driving distance of The Ottawa Hospital, which allowed the hospital-based research assistants to drive to the practices each day to perform spirometry. The practices were chosen because they did not have spirometry on-site or within the community, in order to avoid contamination of results. Several rural communities were selected to assess variability between practices. The practices were sent letters of invitation and then telephoned. The first eight practices that agreed to participate were included in the study.

Subjects
Eligible patients were all patients presenting to their primary care practitioners for any reason, who were at least 35 years of age, and who had smoked at least 20 packages of cigarettes in their lifetime. The patients were administered a brief questionnaire by the clinic receptionist that determined age, smoking history, and willingness to participate. Those patients who were eligible and agreed to participate were approached by the research assistant and signed informed consent. Patients who could not perform spirometry were excluded. The study was approved by The Ottawa Hospital Human Ethics Committee and The Institutional Review Board Services.

Baseline Data Collection
Interviewer-administered questionnaires included questions about smoking, respiratory symptoms, and diagnosed respiratory illnesses taken from the American Thoracic Society questionnaire,4 which has been standardized and tested for reliability. Spirometry was performed in the practice building before the patients were seen by their physicians, by trained research assistants using a portable spirometer (MicroLab 3500; Micro Medical; Auburn, ME). Testing was done with the patients seated, and a maximum forced exhalation was carried out for a minimum of 6 s. A minimum of three and a maximum of eight FVC maneuvers were performed to obtain at least three acceptable loops, two of which were reproducible within 200 mL. The reference values used were those of Knudson et al.5 Hankinson and colleagues6 reported that predicted FEV1 for age was similar whether equations by Knudson et al,5 Crapo et al,7 Glindemeyer et al,8 or Hankinson et al6 were used. All spirometry tests were reviewed by an independent senior cardiopulmonary technologist and two pulmonary medicine specialists to ensure acceptability.

The physicians were informed at the beginning of the study, and when presented with each patient’s spirometry results, that the definition of airflow obstruction to be used in the study was an FEV1/FVC ratio < 0.7. Following the patient’s visit with the physician, but before knowing the results of spirometry, the physicians were asked the following: (1) whether airflow obstruction had ever been diagnosed in the patient, and (2) whether they believed that the patient’s spirometry results would demonstrate airflow obstruction on that day. After seeing the results of spirometry, the physicians were asked whether they thought the current test showed obstruction, whether they would now diagnose airflow obstruction, and whether they planned to change medical management based on the results of the test.

A follow-up chart review was done 6 months after the initial spirometry to look for documentation that medication changes had occurred. Chart reviews were performed for all patients with abnormal spirometry results (FEV1/FVC ratio ≤ 0.70, and/or FEV1 ≤ 80% of predicted) and on an equal number of randomly selected patients with normal spirometry results.

Statistical Analysis
The criterion for diagnosis of airflow obstruction was a prebronchodilator FEV1/FVC ratio < 0.7. Results were stratified by severity based on FEV1. The {chi}2 statistic was used to test associations between the FEV1/FVC ratio < 0.7 (yes/no), the physician’s diagnosis of obstruction (yes/no), and the physician’s plan to change management (yes/no). {kappa} statistics were used to measure agreement between test results and physician’s diagnosis.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
The study included eight rural communities with populations between 1,206 and 4,406. A total of 23 primary care physicians and 1,046 patients participated. Of the 1,046 patients, 1,034 had acceptable and reproducible spirometry results. One hundred eighty patients (17.4%) had airflow obstruction, defined as a prebronchodilator FEV1/FVC ratio < 0.7. There was no significant difference in prevalence of obstruction between the eight study sites ({chi}2 p = 0.17). The mean age of the study patients was 59 years (SD, 12.7), with patients’ having a mean 35.5–pack-year (SE, 28.5) history of smoking (Table 1 ).


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  		Table 1.. Characteristics of the Study Population Stratified by the Presence or Absence of Airflow Obstruction*

 
The entire clinical population that visited the eight primary care practices was surveyed for several days in order to determine the degree to which the study group was representative of all eligible patients. Eighteen hundred patients were 100% sampled from the practices over 4 days; of these, 561 patients (31%) were at least 35 years of age and had ever smoked. The group of 1,046 patients studied with spirometry in this study were similar to all of those eligible from the entire clinic population with the following differences: the studied group was 2 years younger in age, and had accumulated one additional pack-year of smoking compared to the entire population of potentially eligible patients.

From before to after knowing the results of spirometry, the diagnosis of airflow obstruction changed in 20% (208 of 1,030 patients) [Fig 1 ]. For 4 of the 1,034 patients, information on the clinical diagnosis before and after spirometry was missing. Airflow obstruction had not been diagnosed in 93 patients (9%) prior to spirometry but was diagnosed afterwards, whereas 115 patients (11%) had a diagnosis of airflow obstruction removed. Diagnosis before and after spirometry remained unchanged in 822 patients (80%); of the patients in whom the diagnosis remained unchanged, 195 patients (19%) had a previous diagnosis of airflow obstruction (Fig 1).



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  		Figure 1.. Flow diagram of diagnostic changes and management decisions made based on spirometry. AO = airflow obstruction; Mngmt = management.

 
In the 93 patients with a new diagnosis of airflow obstruction, the FEV1/FVC ratio was < 0.7 in 54 patients (58%). For the remaining 39 patients who had a new diagnosis of airflow obstruction by their family physician, the FEV1/FVC ratio was ≥ 0.7. In 22 of these patients, either the FEV1 or FVC was < 80% predicted. However, 17 of the 93 patients with newly diagnosed airflow obstruction based on spirometry had no abnormalities on spirometry. Among the 115 patients believed to have obstruction before but not after spirometry, the FEV1/FVC ratio was ≥ 0.7 in 111 patients (97%).

Following spirometry, each physician was asked, "Based on the results of this spirometry, do you plan to change any aspects of management for airflow obstruction?" The question was answered "yes" in 15.0% (154 of 1,030 patients). Of those with an FEV1/FVC ratio < 0.7, management change was planned in 52.5%, vs 7.0% in those with an FEV1/FVC ratio ≥ 0.7 (p = 0.0001). Among those with an FEV1/FVC ratio < 0.7, the likelihood of planning to change management was increased with the severity of airflow obstruction: 56.9% (82 of 144 patients) with an FEV1 < 80% of predicted, vs 34.3% (12 of 35 patients) with an FEV1 ≥ 80% (p = 0.016). Stratified by the yes/no combinations of prespirometry and postspirometry diagnoses of airflow obstruction, the proportions of planned management change within these combinations were as follows: 61.3% (no, 57/yes, 93); 10.4% (yes, 12/no, 115); 0.8% (no, 5/no, 627), and 41.0% (yes, 80/yes, 195), {chi}2 p < 0.0001 (Fig 1). Management changes described by physicians were usually to counsel patients to stop smoking (n = 44) or to change, add, or subtract medications (n = 98). Other described planned changes included closer evaluation and re-evaluation of patients, encouragement of compliance with medications, and counseling to lose weight.

A chart review of 599 patients (58% of the total sample) done 6 months after spirometry documented the addition of respiratory medications in 48 patients (8.0%). Smoking cessation counseling and withdrawal of medications were generally not charted and therefore could not be assessed through chart review.

Seventy-six of 93 patients with newly diagnosed airflow obstruction underwent a chart review. Of these 76 charts, 5 charts (7%) contained documentation that respiratory medications were added within 6 months of spirometry being performed (Table 2 ).


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  		Table 2.. Addition of New Respiratory Medications Documented by 6-Month Chart Reviews

 
One hundred fifty-five of 195 patients whose spirometry had confirmed the prior diagnosis of airflow obstruction had chart reviews done. Of these 155 charts, 29 charts (19%) contained documentation of addition of respiratory medications within 6 months of spirometry.


   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Previous studies23 of screening spirometry in primary care practice have reported the incidence of newly diagnosed airflow obstruction to range from 8 to 20%. The variation in incidence of newly diagnosed airflow obstruction may in part be explained by the differences in the patient populations studied and by the study definitions used for airflow obstruction. In our study, the addition of spirometry resulted in a new physician diagnosis of unsuspected airflow obstruction in 9% of patients.

Previous studies do not provide information on whether the diagnosis of obstruction could have been accurately established based only on the physician’s assessment without spirometry. Recently, Buffels et al2 reported that office spirometry detected obstruction in 18% (126 of 703 patients) from 35 and 75 years old with reported cough, wheeze, breathlessness, or nasal allergy or hay fever. Airflow obstruction was detected in 4% (9 of 222 patients) without complaints. Buffels et al2 concluded that a questionnaire did not accurately categorize those with spirometry-defined obstruction. Van Schayck et al9 reported that age and cough were the best predictors of an FEV1 < 80% in a survey of 651 smokers from 35 to 70 years old who did not take respiratory medications. The odds ratio for cough was 2.50 (95% confidence interval, 1.14 to 5.52). Patients > 60 years of age were three times more likely to have an abnormal FEV1 than those < 41 years old.

To our knowledge, the impact of spirometry on a physician’s diagnosis and management plan has not been previously studied. To determine the degree to which spirometry influences the clinical diagnosis, the physician’s diagnosis must be documented before spirometry and then again with the results. We found that airflow obstruction was detected in 17% of patients at least 35 years old who had ever smoked, about half of whom had not previously received a diagnosis of airflow obstruction. Our study differed from the study of Van Schayck et al,9 in which patients with a prior diagnoses of any obstructive lung disease were not identified and the FEV1/FVC ratio was not measured.

Despite several studies of the impact of spirometry on smoking cessation, Kaminsky and Darcy10 stated that, "the pulmonary community has yet to see convincing evidence that screening smokers at high risk of COPD will enhance smoking cessation." This comment was made in reference to the study of Gorecka et al,11 who reported that those with moderate or severe airflow limitation were more likely to quit smoking than those with mild or no airflow limitation. The study by Gorecka et al11 did not prove the benefits of smoking cessation counseling since everyone was counseled (no comparison group). Similarly, it did not prove the benefits of spirometry since everyone underwent spirometry (no comparison group). Those with more severe airflow obstruction could have had higher quit rates than those with mild obstruction because they were informed about their spirometry, or alternatively because they differed in other ways, such as symptom severity, from those with milder obstruction.10 Thus, the study by Gorecka et al11 is certainly suggestive of a benefit of spirometry coupled with smoking cessation counseling, and it provides reason for optimism, but it is not conclusive.

Our study was designed to look at how spirometry affects patient management, not to test the impact of spirometry on the effectiveness of smoking cessation, which would ideally require a randomized study comparing structured smoking cessation counseling without spirometry to counseling plus spirometry. Physicians were told that obstruction is simply defined by an FEV1/FVC ratio < 0.7. A handout was provided. When the physician was asked if airflow obstruction was present, the definition was provided on the same page as the question. On the spirometry output, the FEV1/FVC ratio was clearly evident. In 9% of cases, a new diagnosis of airflow obstruction was made, although the diagnosis was sometimes made in spite of a normal FEV1, FVC, and FEV1/FVC ratio. This suggests that primary care physicians may in some cases misinterpret the results of spirometry and that perhaps more physician education is needed before incorporating this intervention into routine clinical practice.

In 15% of cases, the physicians in this study said they would change management based on the results of spirometry, especially when unsuspected obstruction was present and when obstruction was more severe. Our study did not educate physicians about the management of airflow obstruction since the objective was not to determine how to improve management but rather to determine the effect of spirometry on management. Adding education on management would have confounded the determination of spirometry effects since it would have been difficult to separate the influence of physician education from that of spirometry.

Documentation that medication management did indeed change was present in a minority of cases. This may reflect the limitations of chart reviews for purposes of documenting management changes. Primary care physicians generally did not report smoking cessation counseling or withdrawal of medications in the patient charts, so we necessarily limited the review to documentation of new medications. Although the chart reviews were performed 6 months following spirometry, some patient records had no chart entries because they had not had a subsequent encounter with the physician during that period.

We conclude that spirometry detects a clinically significant proportion of airflow obstruction in the primary care setting and influences management plans, especially in patients with more severe disease. Research into the promotion of screening office spirometry should include more studies of clinically important end points such as changes in diagnosis, management, and patient outcomes.


   Acknowledgements
 
The authors thank the following physicians who participated in this study: A. Assemi, M. Buxton, G. Carvers, P. Coolican, M. Crabtree, C. Davis, R. Dawes, C. Deschenes, M. Dolan, W. Domanko, G. Houze, G. Jacques, H. Langill, J. Marston, G. Peters, H. Prins, E. Rivington, N. Soni, A. Thomas, and S. Wicklum. The authors thank Dr. Josiah Lowry for help with the study design. The authors would also like to thank the study research assistants: Gay Pratt, Dominique Bleskie, and Ena Gaudet.


   Footnotes
 
This project was supported by an unrestricted grant from Glaxo-Smith-Kline. Glaxo-Smith-Kline had no role in the design, implementation, analysis, or interpretation of the study results.

Received for publication December 2, 2004. Accepted for publication March 2, 2005.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Ferguson, GT, Enright, PL, Buist, AS, et al (2000) Office spirometry for lung health assessment in adults: a consensus statement from the National Lung Health Education Program. Chest 117,1146-1161[Abstract/Free Full Text]
  2. Buffels, J, Degryse, J, Heyrman, J, et al Office spirometry significantly improves early detection of COPD in general practice. Chest 2004;125,1394-1399[Abstract/Free Full Text]
  3. van den Boom, G, van Schayck, CP, van Möllen, MP, et al Active detection of chronic obstructive pulmonary disease and asthma in the general population: results and economic consequences of the DIMCA program. Am J Respir Crit Care Med 1998;158,1730-1738[Abstract/Free Full Text]
  4. Ferris, BG Epidemiology Standardization Project. Am Rev Respir Dis 1978;118,1-88[ISI][Medline]
  5. Knudson, RJ, Lebowitz, MD, Holberg, CJ, et al Changes in the normal maximal expiratory flow-volume curve with growth and aging. Am Rev Respir Dis 1983;127,725-734[ISI][Medline]
  6. Hankinson, JL, Odencrantz, JR, Fedan, KB Spirometric reference values from a sample of the general U.S. population. Am J Respir Crit Care Med 1999;159,179-187[Abstract/Free Full Text]
  7. Crapo, RO, Morris, AH, Gardner, RM Reference spirometric values using techniques and equipment that meet ATS recommendations. Am Rev Respir Dis 1981;123,659-664[ISI][Medline]
  8. Glindmeyer, HW, Lefante, JJ, McColloster, C, et al Blue-collar normative spirometric values for Caucasian and African-American men and women aged 18 to 65. Am J Respir Crit Care Med 1995;151,412-422[Abstract]
  9. van Schayck, CP, Loozen, JM, Wagena, E, et al Detecting patients at a high risk of developing chronic obstructive pulmonary disease in general practice: cross sectional case finding study. BMJ 2002;324,1370[Abstract/Free Full Text]
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