Theme : Dreams
Obstructive Sleep Apnea Patients Use More Health Care Resources Ten
Years Prior to Diagnosis
John Ronald1, Kenneth Delaive1, Les Roos2, Jure Manfreda2,3
and Meir H. Kryger1
1Sleep Disorders Center, St. Boniface General Hospital Research Center,
Section of Respiratory Diseases, 2Department of Community Health Sciences
and 3Department of Medicine, University of Manitoba, Winnipeg, Manitoba
R2H 2A6, Canada
Abstract
Because Obstructive Sleep Apnea Syndrome (OSAS) patients may be treated
for comorbidities prior to OSAS diagnosis, we examined the health care
utilization records of 181 OSAS patients and those of matched controls.
We compared OSA patient health care utilization for a ten-year interval
prior to diagnosis to those of randomized age-, gender-, and geographically-matched
controls from the general population. We found that OSAS patients used
approximately twice the resources (as defined by physician claims and
stays in hospital) in the ten years prior to their diagnosis. Physician
claims for cases totaled $686,365 ($3,972 per patient) compared to $356,376
($1,969 per patient) for the controls for the length of the study. Utilization
was significantly higher in 7 of 10 years prior to diagnosis. OSAS patients
also had more hospitalizations: they had 1,118 nights (6.2 per patient)
in hospital versus 676 nights (3.7 per patient) for controls over the
ten-year period. Thus OSA patients are heavy users of health care resources
ten years prior to diagnosis.
Current Claim: Apnea patients are heavy users of health care resources
in the ten years prior to their diagnosis with apnea.
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OSAS is a condition which is characterized by disordered breathing during
sleep marked by repetitive periods of cessation of breathing followed
by EEG arousals. This disorder is associated with excessive daytime sleepiness
and the ensuing increased risk of accidents at work and on the road, psychiatric
conditions (mood disorders), cardiovascular disorders (systemic hypertension,
left heart failure, arrhythmias, ischemic heart disease, cerebral infarction)
and death (Yamashiro and Kryger, 1994; He et al., 1988). OSAS is prevalent
in the general population (Young et al., 1993) but remains underdiagnosed
and undertreated (Ohayon et al., 1997). This may be due in part to the
commonly held belief by some that OSAS may not pose a serious health risk
(Wright et al., 1997) and that the diagnosis and treatment of this condition
may thus have a low priority in health care systems.
Because of the associated comorbidities mentioned above, one would expect
OSAS patients to be heavy users of health care resources, not only at
the time of diagnosis, but prior to it as well. In a previous study we
showed heavy usage by 97 obese OSAS patients for two years prior to diagnosis
(Kryger et al., 1996). In this report, we explore how far back this trend
is seen and determine the total cost these patients incurred over that
period based on stays in hospital and visits to doctors' offices. Our
aim was to determine the magnitude of increased expenditure for the decade
prior to diagnosis. We hypothesized that increased health care utilization
would be seen many years prior to diagnosis with OSAS and we believe this
has definite implications for the way the health care community should
view diagnosis and treatment of OSAS.
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Using data collected at the St. Boniface Sleep Disorders Center, we selected
all patients with polysomnographically-proven OSAS who had comprehensive
health care utilization information in the Manitoba Health Database (MHdb),
established in 1970, going back ten years before their diagnosis of sleep
apnea. We then constructed a working database using data from the MHdb.
This working database includes the complete health care utilization information
for 181 OSAS patients and for 3 or 4 randomly selected control subjects
(without known OSAS) for each OSAS patient (34 had 3 controls each, 147
had 4 controls each). The control patients were matched based on age,
gender and postal code (to correct for socio-economic factors) to the
OSA cases. Patients and controls were residents of Manitoba for the length
of the study period and as such, were fully insured for health care the
entire ten years.
Confidentiality for persons in the control group and patient group was
ensured by "scrambling" the patient's health insurance number
and using the scrambled number as their only unique identifier. The data
for the controls matched to each case were combined by averaging to produce
a single virtual control for each case. This allowed us to take advantage
of the large numbers of controls available to provide us with more statistical
power.
The MHdb, described in depth elsewhere (Roos and Shapiro, 1995) makes
this project feasible. It maintains a record of all hospital stays, outpatient
and emergency visits, visits to doctors' offices with relevant diagnoses,
costs and lengths of hospital stay for all residents of Manitoba. This
allows us to track health care utilization of our patients and the controls
over long periods of time. It also allows us to observe the frequency
with which diagnoses of other medical conditions such as hypertension,
myocardial infarction, and cerebrovascular accident correlate with OSAS.
We are able to ascertain total individual usage in any given time interval
and compare to controls.
Any case or control with extreme usage (greater than 100 days in hospital
over ten years) or who was institutionalized was excluded from the study.
This exclusion was performed to limit our sample to "typical"
OSAS patients and "typical" controls and was done prior to analysis
and without knowledge of whether the excluded person was a case or control.
This excluded 22 cases and controls from the study.
Statistical analysis of the data using physician claims as the outcome
measurement was performed using a GLM ANOVA. Scheffe's Multiple-Comparison
Test allowed us to determine whether patients were different from controls
in each of the previous ten years. It is a conservative test examining
all possible pairs that compares each year to every other year for case
and control groups. Differences in admission to hospital were assessed
using Chi-square analysis.
Costs are presented in actual Canadian dollar amounts and are not adjusted
for inflation. The fact that each patient is compared with his or her
own control in the same year ensures that inflation does not skew the
data. Presented total cost may be conservative for this reason, reflecting
the combination of 1984 to 1995 dollars.
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Figure 1
Figure 2
Demographics were established (Table 1) and data analysis was performed
on 181 patients who were, on average, obese, 50 years old and having symptomatic
OSAS. There were more men (145) than women (36) reflecting the gender
bias in both the prevalence and recognition of this condition.
Physician Claims: A strong, statistically significant relationship was
seen between OSAS and heavy use of health care resources in the ten years
studied--physicians claimed per year 1.5 to 2.4 times more for cases than
for controls (p < 0.001) and an interaction was seen which showed the
increasing difference in physician claims approaching the time of diagnosis
(group and year interaction, p < 0.001) (Figure 1). Physician claims
for the patient group totaled $686,365 ($3,972 for each patient) compared
to $356,376 ($1,969 for each patient) for the controls for the length
of the study. The average number of physician claims for patients was
nearly twice that of controls (109 for each patient, 60 for each control
subject over 10 years).
A comparison of patients and controls for each of the ten years revealed
that patients used more physician resources often for each year (from
1.5 to 2.4 as much) and these differences were significant for 7 of 10
years (Table 2). Figure 2 shows that while a difference exists as far
back as ten years prior to diagnosis, the usage by OSA patients increases
greatly approximately four years prior to diagnosis. The small incremental
increases in the control group may be due to aging and inflation but given
the fact that cases and controls are compared for each year, the increasing
difference must be attributed to increasing usage. In other words, inflation
and aging apply to both groups equally and therefore cannot explain the
increasing gap in expenditure. Over the four years prior to diagnosis,
mean annual physician claims increased by $240.67 for patients compared
to $20.41 for controls (Table 2).
Hospital Admissions: OSAS patients had more hospitalizations: they had
1,118 nights (6.2 per patient) in hospital versus 676 nights (3.7 per
patient) for controls over the ten-year period. The fraction of cases
versus controls admitted to hospital in each of the ten years was analyzed
(Table 3). The chance of having had an admission in the ten-year period
was greater for the patient group than for their controls (p < 0.001).
In a similar manner to the increase in the physician claims seen around
4 years before diagnosis (Figure 2) the probability of admission increases
dramatically around 4 years before diagnosis.
Combining total nights in hospital multiplied by $1,000 per night with
actual physician claims for the ten years yields a rough estimate of the
total cost (Table 4). We felt that transforming hospital stay into dollars
using Refined Diagnostic Related Groups (RDRG) would not enhance our understanding
of the overall utilization for this group given the fact that RDRGs do
not include OSAS as a diagnosis.
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Sleep apnea patients use health care resources at approximately twice
the rate of controls as far back as ten years before their diagnosis.
Analysis of the two main components of medical costs, physician claims
and hospital stays, demonstrates the greater utilization in the patient
group. This study likely underestimates cost differences because it does
not take into account costs associated with medications, home care, outpatient
visits, most hospital laboratory tests, or sessional fees covered under
global hospital budgets.
Given the increase in expenditure and length of stay in hospital observed
at 4 or 5 years prior to diagnosis, this time frame will be used for subsequent
investigations. Future research will focus on the factors determining
the utilization of health care resources including analysis of what OSAS
patients are being diagnosed with and treated for. This subsequent work
will be done on a larger number of patients over a five-year span and
will examine relative frequencies of diagnosis and differences between
genders. Patients were not matched to controls for Body Mass Index (BMI)
because that information is not included in the MHdb. Patients are, on
average, obese but were not selected based on BMI but represent a range
of weights. We will examine the contribution of BMI to cost within a stratified
patient group as well as the effect of treatment on cost. These will be
presented in subsequent publications.
Although our results support the conclusion the OSA patients are more
likely to be heavy users of health care resources, other possible factors
should be considered. For example, people with other medical problems
and thus increased contact with the health care system are more likely
to be referred for evaluation of OSA. However, it is worth pointing out
that only 6 of the 690 control subjects had no contact with the health
care system in the 10-year period. This is because all residents of Manitoba
have access to health care. One may infer from the above that it is likely
that apnea was present for several years prior to referral but was undiagnosed,
and therefore untreated. This is consistent with the clinical impression
of the authors that apnea symptoms are often present for years before
apnea is considered.
One possible reason that sleep apnea is underdiagnosed (Ohayon et al.,
1997) is that the amount of time allotted to teaching in medical schools
about sleep disorders is minimal and so most practitioners have had little
or no training in this area (Rosen et al., 1993).
The effectiveness of treatment of OSAS is generally accepted (Yamashiro
and Kryger, 1994). Many patients who are treated with CPAP experience
a dramatic improvement in their quality of life and are able to return
to work and lead productive lives after having been seriously handicapped
by OSAS. The fact that early diagnosis and treatment would improve the
health of OSA patients together with the reduction in overall usage that
would likely follow make education of physicians in detection of OSA and
treatment of patients priorities for health care policy makers. Nevertheless,
as seen in a large survey of the United Kingdom by Ohayon et al. (1997),
OSAS remains underdiagnosed and undertreated and patients continue to
be both ill and financially burdensome on governments and health care
providers.
1. He J, Kryger MH, Zorick FJ, Conway W, Roth T. Mortality and apnea index
in obstructive sleep apnea. Experience in 385 male patients. Chest 1988;
94: 9-14.
2. Kryger M, Roos L, Delaive K, Walld R, Horrocks J. Utilization of health
care services in patients with severe obstructive sleep apnea. Sleep 1996;
19: S111-6.
3. Ohayon M, Guilleminault C, Priest R, Caulet M. Snoring and breathing
pauses during sleep: telephone interview survey of a United Kingdom sample.
BMJ 1997; 314: 860-3.
4. Roos N, Shapiro E. Health and Health Care: Experience with a population-based
health information system. Med Care 1995; 33: 12.
5. Rosen R, Rosekind M, Rosevear C, Cole W, Dement W. Physician education
in sleep and sleep disorders: a national survey of U.S. medical schools.
Sleep 1993; 16(3): 249-54.
6. Wright J, Johns R, Watt I, Melville A, Sheldon T. Health effects of
obstructive sleep apnoea and the effectiveness of continuous positive
airway pressure: a systematic review of the research evidence. BMJ 1997;
314: 851-60.
7. Yamashiro Y, Kryger M. Why should sleep apnea be diagnosed and treated?
Clin Pulm Med 1994; 1: 250-9.
8. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence
of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;
328: 1230-5.
This study was supported by the St. Boniface Hospital Research Foundation
and the Medical Research Council of Canada.
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