Original Contributions

Performance of a New Screening Spirometer at a Community Health Fair

Robin J Schoh MSc MBA, Laura J Fero RN, Howard Shapiro PhD, Jordan P Aslor MBA RPFT, Oscar J Kaelin MSEE, Donald R Rollins MD, and Thomas L Petty MD

OBJECTIVE: Compare the results from a new screening spirometer (Easy One) with the results from a standard laboratory spirometer (Vmax) approved by the American Thoracic Society. SET- TING: A health fair at a community hospital. METHODS: We measured forced expiratory volume in the first second (FEV\) and forced expiratory volume in the first 6 seconds (FEV,,). With the screening spirometer, good quality testing was achieved in 359 of 394 subjects (91%), and 115 subjects were also tested with the standard laboratory spirometer. The best test values for FEVi and FEVg were taken for 3 tests that agreed within 3%. FEVg was extrapolated from forced vital capacity on the printouts from the standard laboratory spirometer. RESULTS: Correlations between the screening spirometer results and the standard laboratory spirometer were excellent for FEV) (r = 0.93), FEVg (r = 0.96), and FEVi/FEVg (r = 0.72) (p = 0.001 for all comparisons). The 95% limits of agreement (mean difference between the 2 spirometers ± 1.96 standard deviations) were: -0.18 and 0.69 for FEVp -0.24 and 0.81 for FEVg; and -0.12 and 0.13 for FEV1/FEV6. CONCLUSION: The new screening spirometer is suitable for clinical use. Key words: screening, spirometry, spirometer, EasyOne, SensorMed- ics, Vmax, health fair. [Respir Care 2002;47(10): 1150-1157]

Introduction

Screening for occult disease is commonplace in the United States.(1.2) Community-sponsored health and wellness programs often offer tests for blood pressure, eyesight, hearing, cholesterol, diabetes, osteoporosis, breast, colon, and prostate cancer, and tests for less common disorders. Such screening is often conducted at community health fairs. Spirometry screening is sometimes done at such events.

Since spirometry is predictive of risk of death from heart attack, stroke, lung cancer, chronic obstructive pulmonary disease, and all-cause mortality, it is an appropriate addition to community health screening projects. One previous community project offered spirometric screening to the entire metropolitan population of Denver, Colorado, on a single day.(3) In fact, 2,586 patients were tested at multiple locations during two 4-hour periods on 2 separate Saturday mornings. Followup showed that such screening, using a new and previously validated electric spirometer,4 yielded credible results.

A new national health care initiative recommends routine spirometry screening of all smokers over age 45 and of anyone with chronic cough, mucus hypersecretion, dyspnea on exertion, or wheeze.(5) That initiative is called the National Lung Health Education Program (NLHEP).(6)

Fig. 1 Participants at the Loveland Health Fair using the EasyOne screening spirometer. The spirometry was conducted by nurses and respiratory technicicans.

In response to the NLHEP several spirometer manufacturers have developed and marketed new, simple, accurate, and inexpensive hand-held spirometers for the purpose of promoting widespread spirometric screening. One such new device (EasyOne, ndd Medical Technologies, Andover, Massachusetts) meets American Thoracic Society standards and has United States Food and Drug Administration approval. We used several EasyOne spirometers at a Saturday-morming community health fair (2 sessions, 4 weeks apart). We aimed to validate the performance of the new spirometer and its agreement with an established Ameri- can Thoracic Society-approved spirometer (Vmax, VIASYS Healthcare/SensorMedics, Yorba Linda, Califor- nia) that is commonly used in pulmonary function laboratories today.

The purpose of this report is to document the performance of the EasyOne device and its agreement with the Vmax spirometer. A secondary aim was to learn the number of abnormal spirometry measurements detected at such a health fair event. A later study will evaluate whether the finding of new spirometric abnormalities resulted in any behavioral changes in subjects whose spirometry was abnormal.

Methods

Following 2 briefing sessions with the hospital wellness, community nursing, respiratory therapy, and administrative staffs, and a familiarity program that emphasized the performance characteristics of the new screening spirometer, we conducted spirometry on a convenience sample of participants at a community health fair. Written, informed consent was obtained from all subjects. The study was approved by the Human Subjects Committee of McKee Hospital, Loveland, Colorado. The community health fair took place between 6:30 AM and noon on 2 Saturday mornings, April 1st and April 29th, 2000, at McKee Hospital, Loveland, Colorado, the only community hospital that serves Loveland, which has a population of about 60,000. Participants came by previously arranged appointments. In all, 1,270 people came for the full array of tests offered. Spirometry had not previously been offered at this annual health fair.

FEV1 Values from Vmax Spirometer (L)
Figure 2. Forced expiratory volume in the first second (FEV1) values from the EasyOne screening Spirometer versus the Vmax Spirometer.

Before the spirometry each subject filled out a 1-page history form that focused on common pulmonary symp-toms, past diagnoses of pulmonary disease, smoking his- tory, family history, and occupational history, and asked about age, height, sex, and weight.

Five screening spirometers were used during the first testing day and 7 during the second testing day. All the spirometers were calibrated with a 3 L syringe. Tests with the Vmax device were all conducted by a respiratory ther- apist with certification in spirometry (ie, a registered pulmonary function technician). The EasyOne devices were used by nurses and other technicians with varied but limited experience in spirometry. These personnel had all received an approximately 1-hour instruction session with the EasyOne. Participant waiting times for testing were estimated to be < 5 min in most cases. Few participants left the waiting queue. Figure 1 illustrates the use of the screening Spirometer. All testing was done with the participants in the seated position. Nose clips were not used. A forced vital capacity test of at least 6 seconds was required.

A minimum of 3 tests were done with both the EasyOne and Vmax devices. The best of the tests that agreed within 3% were recorded for forced expiratory volume in the first second (FEV1) and forced expiratory volume in the first 6 seconds (FEV6). That criterion was arbitrary but within the American Thoracic Society standard of 200 mL for FEV1 and forced vital capacity for values < 6,000 mL.(7) The device gives an audible cue to continue to exhale for a full 6 seconds.

Figure 3. Forced expiratory volume in the first 6 seconds (FEV6) values from the easy One screening spiromter versus the Vmax spirometer.

Figure 4. Comparison of the ratio of forced expiratory volume in the first second (FEV1) to forced expiratory volume in the first 6 seconds (FEV6)

In an attempt to establish agreement between the results obtained for the EasyOne screening spirometer and the Vmax spirometer, as many patients as possible were encouraged to have "confirmatory testing" following the initial screening spirometry. Enthusiasm for the second testing was higher among those patients who had abnormal test results with the screening spirometer. Additional testing was less popular among subjects who had normal results, because there were other screenings they wanted to do at the health fair. As a result, 115 subjects had both spirometric tests. The FEV6 was extrapolated visually and manually for the Vmax spirometer on each expiratory spirogram. In only 1 instance was the FEV6, not achieved with the Vmax instrument, but a plateau was reached.

A pulmonologist (TLP) was present to answer questions that are common when a newly found abnormality is reported to a participant. All test results were printed and each participant was given the results to keep with his or her personal health care record or to take to his or her personal physician.

The statistical methods we used included descriptive statistics and a measure of agreement between the 2 devices. Agreement was evaluated using 95% limits of agree- ment (assuming normality), as described by Bland and Altman.(8) Basically, the 95% limits of agreement (mean difference between the 2 devices ± 1.96 standard devia- tions) are expected to encompass approximately 95% of the population of individual differences. The limits are examined with regard to the clinical acceptance of differ- ences of that magnitude.

Definition of Abnormal

The presence of an obstructive ventilatory defect was defined as an FEV1/FEV6, < 0.70 and an absolute FEV1, less than the lower limit of normal. Normal values for FEV i and FEV6; were obtained from a large population study done as part of the National Health and Nutrition Examination Survey (NHANES III).(9) FEV6, is an accepted surrogate for both obstructive and restrictive ventilatory disorders.(10) A restrictive ventilatory defect was defined as an FEV1/FEV6, of > 0.80 and an FEV6, less than the lower limit of normal. A borderline abnormality was arbitrarily defined by one of us (TLP) as subjects age s 69 with an absolute FEV1 of 2.5 L and an FEV6, of 3.5 L. This is justified by the fact that very mild abnormalities in older subjects are usually not clinically important.(11)

*Vmax readings minus EasyOne readings
FEV1 = forced expiratory volume in the first second
FEV6 = forced expiratory volume in the first 6 seconds

Mean FEV1 of the 2 Spirometers
Figure 5. Difference in forced expiratory volume in the first second (FEV1) between the EasyOne screening spirometer and the Vmax spirometer versus mean FEV1 of the 2 devices.

Results

In all, 394 subjects were enrolled for screening spirometry (149 on April 1 and 245 on April 29). The higher enrollment on the second testing day was attributed to the use of more screening spirometers (5 on the first day, 7 on the second). On the first day, 1 screening spirometer malfunctioned, reducing the total number of screening spirometry stations to 4. There were no other malfunctions of the screening spirometer. Another factor in the higher enrollment on the second testing day was the use of volunteers to assist the subjects in completing the questionnaire prior to spirometry. Incomplete or inadequate test results (ie, failure to successfully complete 3 satisfactory screening maneuvers) occurred with 35 subjects (9%). Thus, good quality testing was accomplished in 359 subjects (Table 1).

Table 1 shows the demographics of the subjects who had 3 apparently satisfactory tests. Table 2 lists the num- ber of normal and abnormal spirometric tests for the 359 subjects.

Spirometer Comparisons

When we reviewed all the spirograms, the results of 2 comparisons were considered "outliers" and excluded from the analysis. These results were outside 3 standard devia- tions. In both subjects the results from the EasyOne screen- ing spirometer were significantly lower than those from the Vmax device: FEV6 3.50 L versus 2.16 L in one subject, and FEV1 3.51 L versus 1.16 L in the second subject. Visual review of those spirograms revealed a poor effort on the screening spirometer in each instance.

Figures 2, 3, and 4 display the line of equality and the paired device results for FEV1, FEV6, and the ratio of FEV1 to FEV6. This is a traditional method of comparing values obtained with 2 instruments. It has the advantage of displaying the actual test results. Table 3 shows the mean differences (Vmax minus EasyOne). Figures 2 and 3 suggest that for FEV1 and FEV6; the EasyOne device slightly underestimated the results of the Vmax device, but this may be due to a learning effect, since the Vmax tests always followed the EasyOne tests, for practical and logistical reasons. Also the Vmax technician had more spirometry experience than the personnel who used the EasyOne. The FEV1/FEV6 ratios show no systematic under-estimation or over-estimation.

Mean FEV6 of the 2 Spirometers
Figure 6. Difference in forced expiratory volume in the first 6 seconds (FEV6) between the EasyOne screening spirometer and the Vmax spirometer versus mean FEV6 of the 2 devices.

The correlation coefficients of the screening spirometer results and the standard laboratory spirometer were excellent for FEV1 (r = 0.93), FEV(, (r = 0.96), and FEV1/FEV6, (r = 0.72) (p = 0.001 for all comparisons). However, the use of correlation coefficients has been criticized,8 so we examined the limits of agreement to evaluate the differences between the results obtained by the 2 devices. The limits of agreement were: -0.18 and 0.69 for FEV1; -0.24 and 0.81 for FEV6>; and -0.12 and 0.13 for FEV1/FEV6.

Figures 5, 6, and 7 plot the differences in FEV1, and FEV6 values and the FEV1/FEV6, ratios between the 2 devices versus the mean FEV1 and FEV6 values and the FEV1/FEV6 ratios, as suggested by Bland and Altman.8 Also included are the limits of agreement. Figures 5 and 6 suggest that there is no systematic bias between the 2 devices. Several observations outside of the limits of agreement were investigated and retained as clinically acceptable.

One of the authors (TLP) independently interpreted the spirometry results. If the 39 borderline abnormal results are omitted from the comparisons, the computerized interpretation by the device agreed with the clinician's interpretation on 92% (330/359) of the spirograms.

Discussion

The NLHEP recommends screening spirometry for all smokers over age 45 and for anyone with chronic cough, mucus hypersecretion, inappropriate dyspnea, or wheeze.5 Testing at the Loveland Health Pair was not restricted to that population. Anyone desiring spirometry was given at least 3 attempts to produce valid results. The majority of the tests (91 %) were of satisfactory quality. The new screening spirometers functioned well throughout the study, with one exception during the first testing session.

The FEV1 and FEV6 values obtained with the EasyOne screening spirometer were in generally good agreement with the Vmax spirometer, which is a commonly used pulmonary function laboratory diagnostic spirometer. A large number of subjects (n = 359) were successfully tested during the total of 9 hours of testing over the 2 Saturday morning health fair sessions.

The EasyOne uses the Doppler principle of flow sensing. It is not affected by altitude (the spirometry reported herein was conducted at about 5,000 feet above sea level). A temperature sensor near the mouthpiece corrects ambient-temperature-and-pressure-saturated (ATPS) readings to body-temperature-and-pressure-saturated (BTPS) readings.

Mean FEV1/FEV6
Fig. 7. Difference between the ratios of forced expiratory volume in the first second (FEV1) to forced expiratory volume in the first 6 seconds (FEV6) versus the mean FEV1/FEV6 ratios from readings from the EasyOne screening spirometer and the Vmax spirometer

We found 63 (17%) subjects with abnormal spirometry readings, which in a health care setting is consistent with results from a random population.10 The arbitrary definition of borderline (age 69 and FEV1 of 2.51 and FEV6 of 3.5) is reasonable. The subjects with only mild abnormalities probably do not need any further evaluation unless they develop symptoms.

It will be important to determine whether knowledge of the spirometric abnormalities discovered at the health fair has caused any behavioral change among those partici- pants or their physicians. Did the participant stop smoking or receive any therapy aimed at improving lung function? These questions are being pursued in an ongoing follow-up study in the community.

The NLHEP Subcommittee on Screening Spirometry recommends validation testing of each new screening device placed on the market following Food and Drug Administration approval. The details of validation recommendations have been published.(5) It is the responsibility of each manufacturer that develops a screening spirometer for widespread application to complete such a validation study before stating that the device meets the NLHEP spirometry recommendations and standards. The health fair study reported herein cannot be considered to have fulfilled those NLHEP recommendations. Our purpose was to gain knowledge about the device's health fair performance and to conduct a preliminary evaluation of its accuracy compared with an established laboratory spirometer.

Another chronic obstructive pulmonary disease initiative is known as the Global Initiative for Chronic Obstructive Lung Disease (GOLD), which is an international organization sponsored by the World Health Organization and the United States National Heart, Lung, and Blood Institute. GOLD recommends the development and testing of simple, user-friendly spirometers for widespread clinical use.(12) "Spirometers need to be developed that can ensure economical and accurate performance when a rela- tively untrained operator administers the test."(12)

Conclusions

The results of this study suggest that the EasyOne spirometer performed satisfactorily in a health fair setting. The agreement between the readings of the EasyOne and the Vmax devices was acceptable for clinical purposes.

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