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* From the Department of Medical Informatics (Drs. Finkelstein and Hripcsak), Columbia University, New York, NY; and the Division of Pulmonary Medicine (Dr. Cabrera), Columbia Presbyterian Medical Center, New York, NY.
Correspondence to: Joseph Finkelstein, MD, PhD, Doctors Office Building, Suite 1102, 720 Harrison Ave, Boston, MA 02118; e-mail: finkelj{at}bu.edu
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Abstract |
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 TOP Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Design: We studied an Internet-based telemonitoring system that collected spirometry data and symptom reports from asthma patients’ homes for review by physicians in the medical center’s clinical information system. After a 40-min training session, patients completed an electronic diary and performed spirometry testing twice daily on their own from their homes for 3 weeks. A medical professional visited each patient by the end of the third week of monitoring, 10 to 40 min after the patient had performed self-testing, and asked the patient to perform the spirometry test again under his supervision. We evaluated the validity of self-testing and surveyed the patients attitude toward the technology using a standardized questionnaire.
Setting: Telemonitoring was conducted in patients’ homes in a low-income inner city area.
Patients: Thirty-one consecutive asthma patients without regard to computer experience.
Measurement and results: Thirty-one asthma patients completed 3 weeks of monitoring. A paired t test showed no difference between unsupervised and supervised home spirometry self-testing. The variability of FVC (4.1%), FEV1 (3.7%), peak expiratory flow (7.9%), and other spirometric indexes in our study was similar to the within-subject variability reported by other researchers. Despite the fact that the majority of the patients (71%) had no computer experience, they indicated that the self-testing was "not complicated at all" or only "slightly complicated." The majority of patients (87.1%) were strongly interested in using home asthma telemonitoring in the future.
Conclusions: Spirometry self-testing by asthma patients during telemonitoring is valid and comparable to those tests collected under the supervision of a trained medical professional. Internet-based home asthma telemonitoring can be successfully implemented in a group of patients with no computer background.
Key Words: asthma • peak expiratory flow • self-management • spirometry • telemonitoring
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Introduction |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Recent advances in information technology have created the potential for home spirometry monitoring. We developed a Web-based system that monitors lung function using spirometry and symptom reports in patients’ homes.13 14 The system provides real-time clinical decision support tools, and it creates a constant reciprocal information exchange between patients and health-care providers.
There are a number of potential obstacles in using our home asthma telemonitoring system. Spirometric measurements usually are performed under the direct guidance of a trained medical technician in a pulmonary laboratory. The validity of the spirometry tests performed by asthma patients at home has not been systematically studied. In a recent publication, Reddel et al15 evaluated unsupervised home spirometry. FEV1, FVC, and PEF were highly reproducible, and variation was within established guidelines. The authors did not, however, compare unsupervised home spirometry to supervised spirometry. Therefore, it remains unclear whether the results of patient self-testing really duplicate those obtained in a supervised maneuver.
Despite our efforts to simplify the use of our self-monitoring system, it may still present a challenge for patients with limited exposure to new technologies. It is unclear what level of computer literacy should be considered as a prerequisite for using such a system or how this would affect patients’ attitudes. The aim of this study was to evaluate the validity of spirometry tests performed by asthma patients at home and to assess the acceptance of the Internet-based home asthma telemonitoring system by inexperienced patients.
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Materials and Methods |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The design, technical features, and capabilities of our monitoring system have been described in detail.13 14 Briefly, patients used a portable spirometer (model V2120; Vitalograph Inc; Buckingham, UK) and a palmtop computer (model HP200LX; Hewlett-Packard; Corvallis, OR) for self-testing at home. The spirometer was connected to the palmtop computer via a serial port. Patients entered symptoms and notes directly into the palmtop computer, which automatically transmitted the results from the patients’ homes to the medical center’s clinical information system via telephone or wireless network. Minutes later, the results could be viewed and analyzed using an Internet Web browser from any location. The system provided twice-daily monitoring of 29 spirometry indexes and viewing of the flow-volume loop and symptom scores. Each spirometry test consisted of a minimum of three expiratory maneuvers. The palmtop software monitored the quality of the pulmonary function tests and, if necessary, prompted the patient to repeat the test to comply with acceptability and reproducibility criteria as required by the American Thoracic Society (ATS) guidelines for spirometry. An automated decision-support server monitored all data traffic and sent electronic mail alerts to physicians whenever the spirometric indexes fell outside predefined guidelines for the patient.
Each patient received an initial 30- to 40-min instruction session during which he was taught how to operate the equipment and perform a maximal expiratory effort for the spirometry test. The patients were instructed to perform spirometry in the morning and evening on a daily basis. After turning on the palmtop computer, the patient was prompted to enter a score between 0 and 3 (0 = none, 1 = mild, 2 = moderate, 3 = severe) in response to a series of simple questions grading their asthma symptoms at the time. After the diary was completed, they received a message to perform the spirometry tests. On completion of the tests, the patient pressed a "print" button on the spirometer, which transferred the results to the palmtop computer and to the medical central clinical information system. The patient’s performance was monitored by the automated decision-support server, and the self-testing data were reviewed by our professional staff. When deviations from the protocol occurred (for example, when the patient failed to perform the test) and when certain clinical conditions were met, the patient was contacted. The patients were able to review all the results of their spirometry tests on their palmtop computer.
Validity of Self-Testing
All patients were visited by the end of the third week of
monitoring by a medical professional experienced in spirometry
(physician or nurse). The visit took place 10 to 40 min after the
patient performed self-testing (test A). The visiting professional
asked the patient to perform the spirometry test again under his
supervision (test B). The patients were not told that their ability to
perform a valid spirometry test was being tested.
Several approaches were used to evaluate the validity of self-testing. Our initial hypothesis was that the results of test A and test B would be no different than if the same trained technician had supervised both tests. We first analyzed the correspondence between test A and test B using the paired t test and coefficient of correlation. We also used recommendations for assessing agreement between two methods of clinical measurement.16 We plotted the difference between the two measurements and their mean in order to detect a relationship between the measurement error and the true value, and we estimated the mean difference and the SD of the differences to assess the "limits of agreement."16 To evaluate the distribution of the error, we used the deviation from the true value, as described by ATS spirometry guidelines.17
In many spirometry studies, the within-subject variability of spirometric parameters is quantified using the coefficient of variation (CV).18 19 20 21 22 23 24 25 26 27 When within-subject variability is estimated as an index of short-term repeatability of a test result within a time frame over which biological variation is unlikely, it represents an intrinsic measurement error of a particular method. We hypothesized that the variability of spirometric parameters caused by differences in the results of test A and test B is comparable to the within-subject variability reported by other studies in which all repeated measurements were performed under the supervision of a trained technician. The estimation of the CV was performed according to recommendations for quality control in clinical trials.28
Patients’ Attitudes
The evaluation of the patient’s acceptance of the home
telemonitoring system was performed according to the guidelines for
assessing telecommunications in health care.29
Patients
were asked to answer a standardized questionnaire at the completion of
3 weeks of telemonitoring. The survey was conducted in the patient’s
home during a scheduled visit. The questionnaire consisted of two
parts. The first part was designed to evaluate the backgrounds of the
patients for pertinence to the use of new technology. This included
demographic data and questions to assess computer literacy as well as
English proficiency and asthma self-perception using a four-grade
scale. The second part of the questionnaire was designed to assess the
patients’ attitudes toward the use of our telemonitoring system. The
questions in this part were intended to obtain insight on several
aspects on their perception of our system. We wanted to learn how
difficult the self-testing was from the patient’s perspective and how
time consuming the daily self-testing routine was perceived to be. Most
of the questions had four answers, graded from 0 to 3. We used an
alternate sequence of answers to different questions, from most
favorable to the least favorable or vice versa, in order to avoid
"expectation" bias and "halo effects."29
30
We
also tried to express our questions in the simplest possible way and to
avoid additional hidden questions inside the original
one.31
All graded choices for patients’ answers included
short explanations, according to published requirements for
questionnaires.29
To assess the quality of our
questionnaire, we measured construct validity32
by an
examination of the correlation between the overlapping or corresponding
characteristics of the patients presented among questionnaire’s
scales.
In addition to two standardized parts, the questionnaire included several nonobligatory questions that asked patients to express their comments and suggestions about the system in free format. The purpose of these questions was to give the patients an opportunity to express in a voluntary and nonformalized way their opinions and feelings about home asthma monitoring.
The results of the survey were analyzed using Fisher’s Exact Test. All statistical analysis has been done using computer software with a statistical database (SPSS, version 6.1 for Windows; SPSS Inc; Chicago, IL). The values given are the average ± SD, if not stated otherwise.
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Results |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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The patients were allowed to review all of their test results on the palmtop computer, but almost half of them (45.3%) reported not taking advantage of this. However, all patients stated that it is important for them to know that the results can be reviewed in the medical center immediately after the test. The majority of the patients felt safer while being monitored by our home monitoring system, and they were strongly interested in using it in the future.
The 
2 test showed significant association
between how complex the self-testing was for the patients and their
level of English proficiency. Significant association also was found
between previous hospitalizations and the level of importance that
patients assigned to the self-testing results being reviewed by medical
staff in a timely manner. There was no association between how complex
the self-testing was regarded by patients and their age, level of
education, or degree of computer literacy. English proficiency and
computer literacy did not influence the frequency with which patients
reviewed results of self-testing at home. Significant association was
found between such parameters as "ATM use" and "Job," "United
States born" and "English proficiency," self-testing complexity
and complexity of spirometry, and palmtop computer or diary. There was
a strong association between English proficiency and how complex it was
for patients to answer the symptom diary.
The open-ended part of questionnaire was answered by 67.7% of respondents. The following were typical responses to the question "what comments can you make about this asthma monitoring program?": "I think that hospitals should have more of these methods"; "Good idea if you are feeling sick"; "I feel it’s very important because a doctor gets my results immediately"; and "It has helped me to become more aware of my asthma." The patients also indicated that they were interested in sending messages via the palmtop computer to the physician.
Table 4 presents a comparison between published data on within-subject variability of spirometric parameters and variability obtained in our study. The variability in our study does not exceed the corresponding variability for patients with pulmonary diseases that has been reported by other studies. This implies that the variability we witnessed can be attributed mostly to the intrinsic measurement error of spirometry and that no significant error was introduced due to absence of patients’ supervision during self-testing.
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Discussion |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In our study, FEV1 was the least variable parameter and FEF75% was the most variable, which was in agreement with previous findings.27 The low variability of repeated spirometric measurements achieved in our study also could be attributed to continuous reinforcement of the self-testing by our telemonitoring system. The results of self-testing, including flow-volume loop, were analyzed using an automated decision-support server and also were reviewed manually by staff in case of doubts about the validity of the self-testing. Patients could be contacted in a timely manner and instructed to perform self-testing again. Another factor contributing to the high performance of patients is the automatic real-time analysis of the tests by the palmtop computer. It was shown by several recent studies that even in the pulmonary laboratories, the introduction of on-line real-time control software checking whether tests meet ATS criteria greatly increases the quality of tests and decreases their variability.26 33
The profile of our patients reveals a high-risk inner city, mostly minority, population, with a level of computer literacy that appeared to be unfavorable toward the successful employment of new computerized technologies. There was, however, a high degree of acceptance of the system. The majority of patients had never used a computer prior to this study. About one half of the patients did not have experience using even an ATM service, which can be considered as a rudimentary analog of computer-based data entry. Despite this, they were able to operate the system successfully. The majority of the patients described the testing, working with the palmtop and answering symptom diary questions as "not difficult at all." The majority of patients who characterized answering symptom diary questions as being "slightly difficult" or "moderately difficult" also scored their English proficiency as poor. The link between English proficiency and patients’ judgments about the complexity of the system strongly supports the necessity to take into consideration language preferences during an installation of a telemonitoring system at a patient’s home.
Most of the patients who described performing the spirometry test and working with the palmtop computer as being "slightly difficult" or "moderately difficult" also indicated that they were not provided with complete information about self-testing during the initial training session. This emphasizes the importance of comprehensive training of patients for successful home telemonitoring. Most of the patients considered one training session sufficient for acquiring all necessary skills for self-testing at home.
Almost all patients expressed a strong willingness to use such a system in the future, and most of them felt safer while being monitored by the system. Surprisingly, about half of the patients reported never reviewing their spirometry results on the palmtop computer. Nevertheless, the same patients indicated that it is important for them to know that their results can be reviewed in the medical center immediately after the test. This may simply indicate that these patients are ready to perform self-testing but prefer the interpretation of the results to be done by a professional staff. The answers to the free-format questions revealed that the most valuable feature of the system for these patients was the timely manner in which a health-care provider could receive and analyze the data.
The positive attitude of the patients toward our home telemonitoring
system did not appear to be due to selection bias. The majority of the
patients had a background that was unfavorable for a successful
acceptance of new computerized technologies. The level of their
motivation or computer literacy had not been taken into consideration
at the beginning of the study. Not only were the patients not paid for
participation in the study, they were responsible for the coverage of
the extra telephone expenditures attributed to telemonitoring
(estimated at $15 per month). The cost-effectiveness of this technology
(cost of the spirometer and palmtop computer) at this time is a
limiting factor toward wider application. The study interval of 3 weeks
may be a limitation of our study given the chronic nature of asthma.
The system does, however, support the monitoring of long-term
compliance by generating alerts if a patient does not perform testing
at preset intervals of 
1 day.
Reddel et al15 argue that a paper diary must accompany the electronic spirometry record to maintain quality control. Their diaries enabled patients to mark tests as invalid (for example, when someone other than the patient performed the test), to correct recorded symptoms, and to clarify context (for example, travel to a new location). In our setting, patients were placed in controlled environments where the validity and clinical significance of each new test were analyzed in a real-time mode and where any important information is immediately sent both to the health-care provider and patients. After a test with an unusual result, the physician can respond in a timely manner, the patient could be asked to repeat the test, or the patient’s self-testing skills could be reinforced. Therefore, the design of our system helps to prevent the pitfalls in home spirometry described by Reddel et al15 and makes possible reliable paperless spirometry monitoring in patients’ homes.
In conclusion, our study demonstrates that the Internet-based home telemonitoring system can be successfully implemented for asthma patients regardless of prior computer background. The spirometry data obtained were valid and comparable to those collected under the supervision of a trained medical professional. The system was well accepted by patients. This system may have a role in monitoring the course of patients’ asthma in their natural home, work environment, or both.
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Footnotes |
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This work was supported by New York State Center for Advance Technology grant Computerized Pulmonary Monitoring Center and by National Library of Medicine training grant LM07079.
Received for publication March 12, 1999. Accepted for publication July 23, 1999.
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References |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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1-antitripsin deficiency. Respir Med 90,131-138[Medline]
1-antitrypsin deficiency: 1-Antitrypsin Deficiency Registry Study Group. Chest 111,899-909This article has been cited by other articles:
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  V. van der Meer, H. F. van Stel, S. B. Detmar, W. Otten, P. J. Sterk, and J. K. Sont Internet-Based Self-Management Offers an Opportunity To Achieve Better Asthma Control in Adolescents Chest, July 1, 2007; 132(1): 112 - 119. [Abstract] [Full Text] [PDF]
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 J. Rigau, F. Burgos, C. Hernandez, J. Roca, D. Navajas, and R. Farre Unsupervised self-testing of airway obstruction by forced oscillation at the patient's home Eur. Respir. J., October 1, 2003; 22(4): 668 - 671. [Abstract] [Full Text] [PDF]
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 M. J. Field and J. Grigsby Telemedicine and Remote Patient Monitoring JAMA, July 24, 2002; 288(4): 423 - 425. [Full Text] [PDF]
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J. Rigau, R. Farre, J. Roca, S. Marco, A. Herms, and D. Navajas A portable forced oscillation device for respiratory home monitoring Eur. Respir. J., January 1, 2002; 19(1): 146 - 150. [Abstract] [Full Text] [PDF]
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 S. Wallace Innovative technology contributes to better asthma management AAP News, May 1, 2001; 18(5): 216 - 216. [Full Text] [PDF]
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 Telemonitoring of Asthma Is Feasible Journal Watch Emergency Medicine, April 1, 2000; 2000(401): 6 - 6. [Full Text]
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