Medicaid Managed Care - U.S. Senate Special Committee on Aging

order) were followed. Samplingpatients
with the same diagnoses across systems
of care and measuring them with the
same methods allowed more valid comparisons
of outcomes across plans. To
better address policy issues, the MOS
oversampled the elderly and the poor.
Focusing on chronically ill patients and
oversampling of the elderly and poor
increased the likelihood of detecting differences
in health outcomes because
these subgroups account for a disproportionate
share of health care expenditures
and are, therefore, prime targets
of cost containment
We report here the results of comparing
changes in physical and mental
health states between FFS and HMO
systems, measured over a 4-year period.
In contrast to previous MOS reports
of outcomes for the average patient,
we focus on outcomes for policyrelevant
subgroups-including patients
aged 65 years and older covered by
Medicare and those near and below the
poverty line. Further, results are reported
for patients across all of the
conditions sampled in the MOS and not
just for patients with hypertension and
NIDDM' and mental disorders."
METHODS
The MOS was an observational study
of variations in practice styles and of
outcomes forchronicaly ill adults treated
in staff-model and independent practice
HMOs vs FFS care in large multispecialty
groups, small, single-specialty
groups, and solo practices serving the
same areas. Details of the MOS design,
including site selection, sampling, clinician
and patient recruitment, and data
collection methods are documented
elsewhere."' To briefly recap the study
design, MOS sites included Boston,
Mass, Chicago, Ill, and Los Angeles,
Calif, which represent 3 of the 4 US
census regions. When sampling began
in 1986 and 1987, these cities included
well-developed HMO and FFS plans,
including 2 of the country's largest
HMOs employing salaried physicians
and 2 of the largest independent practice
association (IPA) networks. In each
city, 5 or 6 practice sites were sampled
from each group practice HMO. The
physician sample included 206 general
internists, 87 family practitioners, 42
cardiologists, 27 endocrinologists, and
65 psychiatrists. In HMOs, patients
treated by 8 nurse practitioners were
also sampled. In addition, patients with
a depressive disorder were sampled
from the practices of 59 clinical psychologists
and 9 social workers. Clinicians
averaged 39.6 years of age; 22%
were female, and 29% were international
medical graduates.
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158
Patient Sampling and Characterstics
Patients followed up longitudinally
were selected from 28257 adults who
visited an MOS site i 1986; 71.6% agreed
to participate. In 18794 (92.9%) of the
visits, a standardized screening form was
completed both by the MOS clinician
and the patient. Using criteria documented
elsewhere,' clinicians identified
patients with hypertension, NIDDM,
myocardial infarction within the past 6
months, and congestive heart failure.
Patients with depressive disorder were
identified independently in a 2-stage
screen, which included a patient-completed
form and a computer-assisted diagnostic
interview by telephone' 80%
of those contacted completed this screening
process.
Patients were selected for follow-up
on the basis of diagnosis and participation
in baseline data collection, as documented
in detail elsewhere.' Inclusion
of patients with more than 1 of the 5
conditions, with or without other comorbidities,
allowed for a more generalizable
study. Of the 3589 eligible patients,
2708 (75.5%) completed a baseline assessment.
We randomly selected 2225
of these for follow-up, by chronic condition
and severity of their disease. A
patient sample of this size was sufficient
to detect clinically and socially relevant
differences in health outcomes, defined
as an average difference of 2 points or
larger on a scale of 0 to 100,' in a comparison
between HMO and FFS systems.
Specifically, the statistical power
was greater than 80%, with a at the .05
level for a 2-tailed test.
Patients ranged from 18 to 97 years of
age, with a mean just under 58 years. At
baseline, 36.8% were 65 years of age or
older, all but 1 reported being covered
by Medicare. (An additional 144 patients
aged into thin group during the 4-year
follow-up.) A slight majority (54%) were
female. About 22% were at or below
200% of the poverty line; 16% of those
reported being covered by <strong>Medicaid</strong>.
Three of 10 eligible for Medicare were
also in the poverty group. Three of4 had
completed at least a 12th grade education;
about I is 5 was nonwhite.
Patients sampled had the following diagnoses
hypertension (n=13 18 ), NIDDM
(n=441), congestive heart failure (n=215),
recent acute myocardial infarction
(n=104), and depressive disorder (n=44 4 ).
(These numbers add to more than 2235
because some patients had more than
one condition.)'' As in previous MOS
analyses,' FFS patients followed up in
this study were significantly older (41.9
vs 32.9 years on average) than HMO patients,
were more likely to be female
(62.8% vs 57.8%), and were more likely
to be in the poverty group (25.4% vs
18.1%). The FFS patients followed were
also more likely to have congestive heart
failure (1138% vs 7.3%) and to have had
a recent myocardial infarction (8.9% vs
3.4%). As documented in detail elsewhere
(MOS unpublished data; see acknowledgment
footnote at the end of this
article for availability of all MOS unpublished
data), 99% of patients followed
in both FFS and HMO systems
had I or more comorbid conditions; the
most prevalent conditions were back pain/
sciatica (39% and 37% in FFS and HMO
systems, respectively), musculoskeletal
complaints (24% and 22%), dermatitis
(17% in each), and varicosities (15%
and 14%).
Longltudlnal Data Collecsion
After screening in the physician's office
and enrollment by telephone interview,
each patient was sent a baseline
health survey by mail.'° The baseline
survey was completed, on average, 4
months afterthe patient's screening visit
with an MOS clinician. Four-year followup
data were obtained for 1574 of the
2235 patients (70.4% of the longitudinal
cohort). Patients were lost to follow-up
for a variety of reasons including refusals
and failure to contact (n=661; 29.6%);
137 (6.1%) who died during follow-up
were included in the analysis. Analysis
of initial health status for those lost to
follow-up for reasons other than death
revealed no differences and loss to followup
was equally likely in HMO and FFS
systems. However, younger and poverty-stricken
patients were more likely
to be lost from both HMO and FFS
systems. All analyses of outcomes adjusted
for age, poverty status, and other
variables to take into account this potential
source of bias (see "Statistical
Analysis").
Health Status Measures
Summary physical and mental health
scales constructed from the Medical
Outcomes Study 36-Item Short-Form
Health Survey (SF-6) were analyzed
(Table 1). These summary measures
capture 82% of the reliable variance in
the 8 SF46 health scores estimated usiag
the internal-consistency reliability
method.>"" The construction of summary
measures, score reliability and validity,
and normative and other interpretation
guidelines are documented
elsewhere."
Changes in health were estimated in
2 ways. First, baseline scores were subtracted
from 4-year follow-updscores,
with deaths assigned a follow-up physical
health score of0 (Table 1). Although
these average change scores have the
advantage of reflecting the magnitude
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