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TELEMEDICINE AND e-HEALTH
Volume 11, Number 1, 2005
© Mary Ann Liebert, Inc.
Improving Asthma Control Through Telemedicine:
A Study of Short-Message Service
VEDRAN OSTOJIC, M.D.,
1
BRANIMIR CVORISCEC, M.D., Ph.D.,
1
SANJA BARSIC OSTOJIC, M.D.,
1
DIMITRY REZNIKOFF, M.D.,
2
ASJA STIPIC-MARKOVIC, M.D., Ph.D.,
1
and ZDENKO TUDJMAN, M.D.
ABSTRACT
Home peak expiratory flow (PEF) measurement is recommended by asthma guidelines. In a 16-
week randomized controlled study on 16 subjects with asthma (24.6 6.5 years old, asthma du-
ration ∃ 6 months), we examined Global System for Mobile Communications (GSM) mobile
telephone short-message service (SMS) as a novel means of telemedicine in PEF monitoring.
All subjects received asthma education, self-management plan, and standard treatment. All mea-
sured PEF three times daily and kept a symptom diary. In the study group, therapy was ad-
justed weekly by an asthma specialist according to PEF values received daily from the patients.
There was no significant difference between the groups in absolute PEF, but PEF variability
was significantly smaller in the study group (16.12 6.93% vs. 27.24 10.01%, p 0.049). forced
expiratory flow in 1 second (FEV
1
; % predicted) in the study group was slightly but signifi-
cantly increased (81.25 17.31 vs. 77.63 14.80, p 0.014) and in the control group, unchanged
(78.25 21.09 vs. 78.88 22.02, p 0.497). Mean FEV
1
was similar in the two groups both be-
fore and after the study. Controls had significantly higher scores for cough (1.85 0.43 vs.
1.42 0.28, p 0.05) and night symptoms (1.22 0.23 vs. 0.85 0.32, p 0.05). There was no
significant difference between the groups in daily consumption of inhaled medicine, forced vi-
tal capacity, or compliance. Per patient, per week, the additional cost of follow-up by SMS was
A
€ 1.67 (equivalent to approximately $1.30 per 1 Euro), and SMS transmission required 11.5 min-
utes. Although a study group of 40 patients is needed for the follow-up study to achieve the
power of 80% within the 95% confidence interval, we conclude that SMS is a convenient, reli-
able, affordable, and secure means of telemedicine that may improve asthma control when
added to a written action plan and standard follow-up.
1
Division of Clinical Immunology and Pulmonology, Department for Internal Diseases, General Hospital “Sveti
Duh,” Zagreb, Croatia.
2
Department of Internal Medicine, Winthrop University Hospital, Mineola, New York.
INTRODUCTION
T
HE PREVALENCE OF ASTHMA
, a chronic illness
with considerable morbidity and mortality,
has been increasing.
1,2
A combination of in-
haled corticosteroid (ICS) and long-acting
2
-
agonist (LABA) is often effective in sympto-
matic control. Dosing of these drugs is influ-
enced by patient’s symptoms, forced expira-
tory volume in the first second (FEV
1
), and
peak expiratory flow (PEF). Disease exacerba-
tion occurs even in optimally treated compli-
ant subjects with asthma, but poor compliance
among them is frequent.
3
Consistent follow-up
28
5494_02_p28-35 3/9/05 4:24 PM Page 28
IMPROVING ASTHMA CONTROL
29
is therefore advisable and recommended by the
current guidelines.
4,5
Control of asthma may be
assessed by the symptom score noted by the
patient in a diary and by office pulmonary
function tests (PFT). Although not a substitute
for full PFT, PEF obtained by the patient at
home with a peak expiratory flow meter
(PEFM) may provide additional insight into
day-to-day asthma activity and may facilitate
disease control. Problems with compliance and
reliability limit the use of symptom diaries and
PEF measurements.
3,6–8
Another means of care-
ful asthma follow-up is regular consultation
with an asthma specialist.
The optimal strategy of asthma assessment
and monitoring has not been established, be-
cause evidence to date has been inconsis-
tent,
9–12
but combining measurement of PEF
with physician follow-up might considerably
improve asthma control, especially if the physi-
cian had immediate access to daily PEF mea-
surements. This can be conveniently achieved
with the use of a messaging service incorpo-
rated into conventional Global System for
Mobile Communications (GSM) mobile tele-
phones, the short-message service (SMS).
Our aim was to assess the feasibility and re-
liability of GSM SMS as a tool of asthma mon-
itoring and to ascertain its impact on control of
asthma.
PATIENTS AND METHODS
Sixteen patients with asthma from our clinic
(9 males, mean age 24.6 6.5 years) experi-
enced in SMS were enrolled in this prospective
randomized clinical trial. All had moderate
persistent asthma for at least 6 months and
were being treated with ICS and LABA. None
had a history of smoking, chronic bronchitis, or
emphysema. Patients without consistent access
to a cell telephone or unable to use SMS were
excluded. No patient withdrew from the study
after enrollment.
Each patient had a 1-hour asthma education
session with a specialist at the clinic, in which
were discussed symptoms of asthma and the
asthma symptom score (Table 1), indicators of
asthma control and exacerbation, use of med-
ication, and the correct technique for using me-
tered dose inhalers (MDI) and PEFM. A mini-
Wright PEFM of the same model was issued
for each patient. The patients were to note PEF
measurements, medication use, and symptoms
in a paper diary. PEF was to be determined
three times per day: immediately upon waking
in the morning, at 4:00
PM
, and at bedtime. Each
PEF measurement was to be performed three
times and the highest value recorded.
Patients were randomized by computer into
either the SMS study group or the control
group. Patients in the SMS group were in-
structed to send their PEF results daily via SMS
to our Ericsson
®
SH 888 GSM mobile telephone
(Ericsson Mobile Communications, Research
Triangle Park, NC), connected via a serial
port to a Pentium processor-based computer
running the Asthma Center 0.90 Software
(Polimedika d.o.o., Zagreb, Croatia). The soft-
ware automatically computed maximal, mini-
mal, and mean PEF, PEF variability, and com-
pliance. PEF values were displayed graphically
in relation to the green, yellow, and red zones
of asthma control (80%, between 50% and
80%, and 50% of predicted PEF, respectively).
Office spirometry was performed before and
after the study. Both groups were treated ac-
cording to GINA guidelines,
5
but the patients
in the SMS group received weekly instructions
T
ABLE
1. S
YMPTOM
S
CORE
Maximal
Wheezing Cough Sleep quality tolerated activity
0 None None Sleeping all night Regular
1 Mild In the night Waking up: no medication required
a
Moderate
2 Moderate Frequent Waking up: medication required
a
Reduced
3 Severe All day Awake all night Rest
a
Medication required for immediate control of symptoms.
5494_02_p28-35 3/9/05 4:24 PM Page 29
by SMS from an asthma specialist on adjust-
ments of therapy and recommended follow-up,
based on PEF values received from them by
SMS. When data received from a patient in the
SMS group indicated significant asthma exac-
erbation (progressive decrease in PEF or PEF
50% predicted despite change-of-treatment
advice), a request for an office visit was sent to
the patient by SMS. The controls were seen in
the office at the end of the study period, when
their diary data were reviewed. Study design is
illustrated schematically in Figure 1.
The data collected over 16 weeks of study
comprised office PFT measurements; clinical
records from the study period; patient’s daily
records of PEF and symptoms; demographic
data; and details of asthma medication. PEF
variability (PEFV) defined as the difference be-
tween the maximal and the minimal PEF mea-
surements of a day divided by the maximal PEF
for that day. Differences within and between
groups were analysed by Wilcoxon signed rank
test. Contingency
2
test was used on discon-
tinuous variables. Results were recorded as
mean standard deviation. Statistical signifi-
cance was defined by a p value 0.05. SMS was
compared to standard follow-up, represented
by controls, regarding PFT results, compliance,
and cost in terms of time and money for physi-
cian and patient. Reliability of SMS was deter-
mined by comparing the SMS database with
the patients’ diaries.
RESULTS
Table 2 is a summary of study data. Figures
2–4 show the findings of FEV
1
, PEF, and symp-
toms, respectively. There were 21 office visits,
2 hospital admissions, and 35 changes of med-
ication in the study group, and 15, 7, and 29,
respectively, in the control group. Six of the 21
visits in the study group were requested by
monitoring physicians. PEF was highest at bed
time and lowest in the morning. PEF variabil-
ity was significantly smaller in the study group
(16.12 6.93% vs. 27.24 10.01%, p 0.049).
There was no difference in compliance with
PEF measurement (66% vs. 61%, p 0.878) or
absolute PEF (p 0.721 for morning; p 0.505
for afternoon; p 0.520 for evening) between
the groups.
At 16 weeks, FEV
1
(% predicted) in the study
group was slightly but significantly increased
(81.25 17.31 vs. 77.63 14.80, p 0.014) and
in the control group remained unchanged
(78.25 21.09 vs. 78.88 22.02, p 0.497). Ac-
cording to Altman’s nomogram, FEV
1
power
calculation yielded a value of 40%. No differ-
ence was found in mean FEV
1
between the two
groups either at the beginning (p 0.798) or at
the end (p 0.573) of the study. Controls had
considerably higher symptom scores for cough
(1.85 0.43 vs. 1.42 0.28, p 0.05) and night
symptoms (1.22 0.23 vs. 0.85 0.32, p 0.05)
but not for wheezing or limitation of activity.
There was no difference between the groups
with respect to daily consumption of inhaled
medicine (steroids: 625 332 vs. 530 200 g,
p 0.574;
2
-agonists: 118 63 vs. 84 28 g,
p 0.383) (Fig. 5) or forced vital capacity (p
0.959). Compliance with SMS transmission of
PEF was 99%. In all, 1769 SMS messages were
received from the patients in the SMS group
(221 per patient), and 139 messages were sent
to them, including 6 requests for urgent visit
and 5 unscheduled medication changes.
Per patient, SMS cost 0.67 (Euros) per week
more than standard follow-up, and added 11.5
minutes per week to the time spent on home
PEF monitoring. Physician time was 2 minutes
per week per patient at a cost of
A
€ 1 (Euro) per
week per patient.
Eighteen more SMS messages were received
than there were corresponding entries in the
patients’ diaries. Of these, 12 were duplicate
messages and 6 represented data sent by SMS
but not recorded in the diary. No SMS message
OSTOJIC ET AL.
30
FIG. 1. Study design.
5494_02_p28-35 3/9/05 4:24 PM Page 30
IMPROVING ASTHMA CONTROL
31
appeared to have been lost, and no data cor-
ruption by transmission was detected.
DISCUSSION
We conclude that asthma overall was better
controlled in the SMS group, based on our find-
ing of reduced PEF variability and slightly but
significantly improved FEV
1
as well as better
symptomatic control in the intervention group
but not in the controls. Because both groups fol-
lowed the same self-management at acceptable
levels, confirmed by written diary, we attribute
this difference to the approximately 20% higher
dose of ICS and LABA in the intervention
group and to the benefit of advice on other as-
pects of asthma control regularly conveyed to
T
ABLE
2. P
ATIENT
C
HARACTERISTICS AND
S
TUDY
F
INDINGS
Variable Study group Control group p value
Number of patients 8 8
Male (%) 63 50
Age (years) 24.8 6.3 24.5 7.1
Medical history (%)
Smoking 0 0
Chronic bronchitis 0 0
Emphysema 0 0
Events during study period
Acute respiratory illness 8 6
Office visits 21 15
Hospital admissions 2 7
SMS messages 1769 0
Compliance with PEF measurement (%) 66.2 16.9% 61.3 22.9% 0.878
PEF values transmitted (% measured PEF) 99 0
Changes of medication 35 29
Average symptom score
Wheezing 0.80 0.77 0.89 0.88
Cough 1.42 0.28 1.85 0.43 0.028
Sleep quality 0.85 0.32 1.22 0.23 0.021
Maximal tolerated activity 0.54 0.50 0.84 0.75
Spirometry
FEV
1
(% predicted)
Beginning of study 77.63 14.80 78.88 22.02 0.798
End of study 81.25 17.31 78.25 21.09 0.573
p 0.014 p 0.497
PEF by time of day (L/min)
Morning 380.00 44.08 365.15 30.42 0.721
Afternoon 405.35 45.67 385.48 31.17 0.505
Evening 415.27 45.67 395.60 30.75 0.520
PEF variability (%) 16.12 6.93 27.24 10.01 0.049
Forced vital capacity (% predicted)
Beginning of study 88.63 14.50 86.63 12.14 0.721
End of study 87.63 15.12 89.00 15.40 0.959
p 0.496 p 0.292
Daily consumption of inhaled medication (g)
Steroid 625 332 530 200 0.574
Long-acting
2
-agonist 118 63 84 28 0.382
Cost of monitoring (per week, per patient)
Money (
A
€ )
Patient 0.67
Physician 1.00
Time (min)
Patient 26.2 14.7
Physician 2.0 0
SMS, short-message service; PEF, peak expiratory flow; FEV
1
, forced expiratory volume in 1 second.
5494_02_p28-35 3/9/05 4:24 PM Page 31
these patients. The effect of medication dose
has been observed previously.
13,14
The lowest
absolute PEF was in the morning for all pa-
tients. This is well known
15
and is thought to
relate both to the relatively low levels of med-
ication at that time and to intrinsic airway
properties.
16,17
As a whole, patients in both
groups had good asthma control, as indicated
by average symptom scores, FEV
1
(approxi-
mately 80% predicted), and absolute PEF
(lower limit of normal: 400 L/min to 500
L/min
18
). Symptom profile, considered as one
of the most important markers of asthma con-
trol, was better in the intervention group. This
was significant only for cough and for night
symptoms. We postulate this is because wheez-
ing, unless significant, is harder to classify or
to perceive at all for the patient as compared to
other symptoms, and a clinically significant dif-
ference may not be detected. The same reason-
ing applies to limitation of activity. Cough
showed the highest average absolute value.
This is likely because cough is easily noticed
and because other conditions common to pa-
tients with asthma, such as environmental al-
lergies, postnasal drip, and upper respiratory
tract infection, commonly cause cough. The ad-
ditional cost of monitoring was minimal in
terms of both time and money. Patients thought
SMS was convenient, and it did not intrude into
their daily activities. This is consistent with
findings of previous studies of telemedicine in
asthma,
19
and is confirmed by the nearly per-
fect compliance with PEF transmission by SMS.
Annual cost of asthma per patient may be as
high as
A
€ 3,000 (Euros).
20
Hospital expenses ac-
count for half of this amount.
21
A self-man-
agement program has been found to improve
asthma control
22
and to reduce the annual cost
of the disease by some A€ 500.
23
Because in our
study no consistent hospital admission criteria
were in place and no particulars of hospital ad-
missions were disclosed to us, and because the
study population was small, we cannot make
firm conclusions about the impact of our
method of telemedicine on asthma-related hos-
pitalization. Notwithstanding, our finding of
improved asthma control with SMS telemedi-
cine as compared with a self-management plan
suggests that the method, at a minimal cost,
may producer greater savings than those re-
ported previously.
To date, telemedicine in asthma has in-
cluded the use of telephone to transmit breath
sounds
24
and spirometry data
25
for assess-
ment of disease severity, Internet-based mon-
itoring systems,
26
and videoconferencing.
27
We used familiar, universally available mo-
bile equipment that offers flexibility and se-
curity of communication. Facsimile has simi-
lar characteristics but lacks the same level of
security and is more difficult to integrate into
automatic data analysis systems, which is
true also of telephone voice communication.
Several of the previous studies of telemedi-
cine in asthma by means of electronic down-
load of spirometry data demonstrated no sig-
nificant difference between the study and
control groups,
19,25,28
but this is likely be-
cause of their much shorter study duration
(3–4 weeks) and may also be related to study
design. A theoretical limitation of SMS is the
possibility of erroneous electronic data entry
OSTOJIC ET AL.
32
FIG. 2. Forced expiratory volume in 1 second (FEV
1
)
(n 616).
FIG. 3. Peak expiratory flow (PEF) by time of day (n
16).
5494_02_p28-35 3/9/05 4:24 PM Page 32
IMPROVING ASTHMA CONTROL
33
by the patient. This cannot be completely
avoided, but the alternative, telephone voice
communication of spirometric data, is prone
to as much or more error, because it requires
data entry into the computer by the receiving
health care team, which must deal with many
measurements of several patients at once. Our
setup allows automated data entry into the
software once the message is transmitted. In
addition, SMS circumvents the difficulties in-
herent in telephone voice communication, in-
cluding engaged lines and the requirement of
continuous staffing of the call center. Human
error can be excluded entirely only by auto-
matic transmission of the data, without any
participation by the patient, by the spirome-
ter or peak flow monitor. These devices rarely
possess this capability at this time. In this
study, we have found SMS to be 100% reliable
with respect to both message transmission and
data integrity. Similar results should be ob-
tained in practice, as long as patients are ad-
equately instructed and the system receiving
SMS is correctly set up.
Current guidelines recommend that asth-
matics should be educated in and advised
about monitoring their disease and that they
should adhere to a written self-management
plan.
4,5
Also recommended is regular follow-
up with an asthma specialist guided by pa-
tients’ continuous objective assessment of dis-
ease activity by means of a symptom diary and
home peak flow monitoring, in addition to of-
fice spirometry. A combination of all these
FIG. 5. Average daily dose of inhaled corticosteroids (ICS) and long-acting
2
-agonists (LABA) in short-message
service (SMS) over time (weeks of study).
FIG. 4. Symptom score (n 16).
5494_02_p28-35 3/9/05 4:24 PM Page 33
means should overcome individual limitations.
In particular, symptom monitoring, a true mea-
sure of disease activity in theory, has serious
limitations related to the variable and subjec-
tive nature of perception of symptoms,
6,29
in-
cluding consistent underestimation of noctur-
nal symptoms.
30
PEF monitoring complements
symptom diary by introducing an objective
measure of airway obstruction. Measurement
of PEF by a PEFM was found to be very con-
sistent repeatedly and also accurate compared
to a full-function office spirometer.
31,32
PEF
measurement may be especially valuable in pa-
tients with asthma who poorly perceive their
symptoms. Several studies showed PEF moni-
toring to be beneficial, with reduced number of
exacerbations and hospital admissions,
10,11
al-
though this may not be true in mild asthma.
22
One-time or occasional spirometry, however,
greatly limits one’s ability adequately to assess
and follow asthma.
33
Continual assessment is
advised. Yet, this too may be difficult to
achieve. Although short-term compliance with
PEF monitoring was approximately 60% in pre-
vious studies, it progressively diminished with
time. By 6 months of follow-up it was only ap-
proximately 40%.
3
PEF values recorded in pa-
tients’ diaries, moreover, may often be inaccu-
rate, and are easily misreported.
34
In a previous
study, patients questioned about home PEF
monitoring found the procedure simple and
quick, but would measure PEF no more than
twice per day.
19
In view of the foregoing, a
symptom diary together with PEF measure-
ment once-per-day in the morning before bron-
chodilator administration may represent the
optimal approach to continuous monitoring of
stable asthma, and our method of telemedicine
may be the optimal means for this. Alterna-
tively, telemonitoring may be reserved for pa-
tients with at least moderate disease who in-
adequately perceive their symptoms or for
short-term monitoring of newly discovered
asthma, of persistently worsening disease, and
of the patients who may be poorly compliant
with treatment.
This study is limited by the small number of
patients and by the particulars of the population
studied (young persons without history of
smoking, chronic bronchitis, or emphysema). A
study powered at 80% within the 95% confi-
dence interval would require a study group of
40 patients. The follow-up period may not have
been sufficiently long to reveal all significant dif-
ferences between the groups. No conclusion
could be drawn from the difference in hospital
admission rate, as explained earlier. The study
was not blinded, but this, we believe, has not in-
fluenced the outcome. First, compliance was not
significantly different in the two groups. Second,
the patients in both groups were managed by
the same current guidelines. Despite the limita-
tions and the need for larger confirmatory
studies, we believe this study has established
feasibility and utility of SMS as a means of
telemedicine of asthma. Its use in asthma may
contribute to better disease control, sympto-
matic improvement, and a more favorable spiro-
metric profile. The same method of telemedicine
may be useful in other situations in which re-
peated prompt communication of data from pa-
tient to physician is of clinical benefit.
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Address reprint requests to:
Vedran Ostojic, M.D.
Division for Clinical Immunology
and Pulmonology
Department for Internal Medicine
HR-10000 Zagreb
Croatia
E-mail: vostojic@astma.hr
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