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Patient Origin Study Guidelines
PRIMARY CARE NEED/DEMAND ASSESSMENT
PART 1:
SERVICE AREA DEFINITION
A health center’s service area is defined as the geographic area in which 80% of its current
patients live. It should be:
•
outlined on a map, and
•
defined in U.S. Census Bureau geopolitical units (e.g., village, town,
township) listing either counties, census tract numbers or minor
civil divisions. The percent of patients living in each of these census
areas must be identified. Use census tracts in Standard
Metropolitan Statistical Areas (SMSAs) and minor civil divisions
elsewhere. If an area is not in an (SMSA) but is tracted urban area,
census tracts may be used.
Note: Throughout this guidance it is assumed that centers will use the most current census
boundaries and data.
EXAMPLE:
The center’s service area consists of the following census tracts and
patient loads:
Census
Tract
Number
Health
Professional
Shortage Area
Estimated # of
Patients
% of Patients
by Census Tract
*107
109
110
56
57
58
No residents of
defined service
area
yes
no
yes
yes
yes
no
N/A
2,000
500
1,000
1,500
2,700
300
2,000
20%
5
10
15
27
3
20
10,000
100%
*Census tract where center located.
Census tract or minor civil division breakdowns for the center’s area can be obtained from
local city or county planning offices.
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In order to locate current patients the center will need to identify their local addresses.
This can be done either by prospectively counting all patients for a month or
retrospectively by random sampling of clinic records. The center should choose the easier
method. The center may wish to sample some records to see how complete their addresses
are and how easily they may be matched to United States Census areas. If, for example,
more than 20% of records show only RFD numbers or third party addresses (e.g.,
Medicaid), the center should turn to a prospective universal count.
METHOD A:
Prospective Universal Count:
Over a month period record the current address of each patient as he/she requests
service. Payment source and position on sliding fee scale (e.g. 50% of 100, 150, or
200% of poverty) could also be recorded if this information could be used later.
METHOD B:
Retrospective Universal Count (For those centers with Computerized Record
Systems): The center may choose to do a universal count retrospectively as long as
only the records of those users with an encounter within the last 2 years are used.
METHOD C:
Retrospective Random Sampling: The appropriate set of center records (billing,
registration, or medical) is randomly sampled for information on patient residence
and payment source. Since we are interested only in current users, only records of
patients seen within the past 2 years should be sampled.
•
Sample Size
For centers having fewer than 2,000 patient records, the sample must
consist of at least 100 records.
•
All other centers will sample 200 records.
•
Muti-site projects
•
Grantees which have multiple sites that maintain separate records
systems may apportion the total sample size among the sites based on
the percentage of records kept at each site. (For example, if billing
records were being pulled for this information, 20% of them would be
sampled where the site generates 20% of the total project billing
records.) If the apportioning yields on or more sites with less than 50
records to be sampled, then a minimum of 50 records should be
included in the sample data for each of the sites.
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•
Procedure
1) Determine which set of center records will be sampled for the
information (billing, registration, medical, etc.).
2) Put the records in order, alphabetically or numerically.
3) Start by pulling the 52nd record (The number 52 was chosen
from a table of random numbers.)
4) If this set of records is filed in one place then pull the records
as in this example:
EXAMPLE: The center has decided that medical records will be
sampled because each record contains the needed information on
patient residence and payment source. It is also known that center
files these records in one place and that there are a total of 1,200
presently filed. Since the center has fewer than 2,000 records, a
total of 100 records will be pulled, or every 12th record in the file.
The first record pulled is the 52nd one from the beginning of the
file then every 12th record after this one is pulled until 100 records
are obtained. Each family counts as one record. Remember to
pull only records of current users (those patients or families with
an encounter within the last two years.) If a pulled record cannot
be used, then select the next record in the file and resume counting
from that one. If the sampler reaches the end of the file without
completing the sample, begin again, at the front while keeping the
same sequence. Record how many records were not used because
they were too old, had incomplete addresses, etc.
5) If the center chooses to sample a type of record which is not
filed in one place, then sampling can be done as in this
example:
Example: The center has decided that billing records will be
sampled because this is the only record system which contains
information on both patient address and payment source.
However, these records are divided into three separate files:
File #1 (Awaiting billing)……… 200 records
File #2 (Awaiting payment)…… 600 records
File #3 (Payment received)……1200 records
2,000 records
Since the center has 2,000 records, 200 records will be sampled. To make sure that the
sampling is done proportionately to the number of records in each file, this number of
records was sampled from each:
3
File #
% of Total Records
1
2
3
10%
30%
60%
# Sampled
20
60
120
200 records in sample
Beginning with the 52nd record in each file and every 10th record thereafter, 20 records are
pulled from File #1, 60 records from File #2, and 120 records from File #3. The total
number of records pulled is thus 200. And, as in the previous example, only records of
current users are to be sampled. If a pulled record is not usable, the next record should be
pulled and the count started over with that record.
Finally:
(1)
match the addresses to the appropriate Census division;
(2)
outline the service area on a map. Be sure to draw boundaries only around
U.S. Census areas (e.g., do not show ½ a census tract or minor civil division);
(3)
list the census areas, whether they are MUAs or HPSAs, or state designated
underserved areas, the estimated number of patients, the percent in each
census area, and the service delivery sites’ locations.
Note that:
Use of zip codes rather than addresses is not accurate enough for this
purpose.
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PRIMARY CARE NEED/DEMAND ASSESSMENT
APPENDIX A
TECHNIQUES FOR CONDUCTING PATIENT ORIGIN STUDIES
A patient origin study is a method for determining those geographic areas from
which a major portion of a primary care center’s current patients are derived. (Current
patients are those patients who have been seen within the last year.) Patient origin studies
can also be used to compile information on the economic status of center patients, their
insurance coverage patterns, and their range of health problems. To conduct a patient
origin study, a center must have the following information:
1.
A complete listing of the center’s current patients and their addresses, and
2.
A census tract map by which patient addresses can be linked to specific
geopolitical (e.g., census tract, county) boundaries.
The decision as to how the patient origin study will be conducted will depend on the
center’s age, the manner in which patient records are maintained, and the total number of
center patients. There are three options:
Method A – Prospective Universal Count
Information is recorded on the residences of all patients who are seen in a given
month. Since patient utilization will show seasonal variations, prospective counts
should be done for a month when patient utilization patterns are considered typical.
Method B – Retrospective Universal Count
Information is recorded on the residences of all current patients (i.e., patients seen
during the last year).
Method C – Retrospective Random Sampling
Information is recorded on the residences of sample of current patients.
The reliability of the patient origin results will depend on the reliability of the
information base that is used. The information base should be as complete as
possible. If the entire patient file is not used, sampling procedures should be chosen
to ensure that the patient information recorded is representative of the center’s
patients. Centers should select the method that is suitable to the center’s resources
and easiest to perform.
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1.
RECOMMENDED PROCEDURES FOR COMPLETING PATIENT ORIGIN
STUDIES
1.1.
METHOD A – PROSPECTIVE UNIVERSAL COUNT
This method is particularly appealing for a small center or a new center. A
center may also choose this method if its patient files cannot easily be used to compile
information on patient residences because the addresses of registrants are either
incomplete, out of date, or not suitable for assigning to census tracts. The following
cautions should be observed if this method is chosen:
1.
In recording patient information, the center should be aware of seasonal
variation and should select a month considered to be typical of patient
utilization.
2.
In recording patient information, attention should be given to users
rather than encounters. Information on individual patients should not be
compiled more than once.
The objective of this method is to obtain information on a sufficient number of
patients to be able to generalize to the center’s entire patient population. Centers with
fewer than 2,000 records, should collect information on at least 100 records. Centers with
more than 2,000 records should collect information on at least 200 records. If a center
has an average of 400 encounters per month, an unduplicated count of users would be
estimated at between 200 and 300 per month, an appropriate number for determining
service area boundaries. Some center may need to record patient information for slightly
more than one month to obtain information on at least 200 users.
Recording information will be facilitated by the use of a form such as the one
provided below. This will allow the recording of all the information necessary for the
need/demand assessment including patient address, payment source, and income. As
each patient arrives, the appropriate information should be recorded during the sample
month.
Patient index cards should be filed alphabetically so that persons with multiple
visits can be identified and duplication in the recording of information can be avoided.
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SAMPLE INDEX CARD
Sex:
Age: (use date of birth & age)
Ethnicity: (if available)
Address:
Census Tract #:
Minor Civil Division:
Payment Source:
level)
Family Income: (note sliding fee eligibility as well as annual income
Family Size:
Name: (use to check sex of patient)
Health problem prompting the visit:
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1.2
METHOD B – RETROSPECTIVE UNIVERSAL COUNT
This method is generally used when an automated data base is available. In order
to use a retrospective universal county to conduct a patient origin study, a center must be
able to:
1.
Identify current users (those patients who have been seen during the last
year).
2.
Link patient residence information to geopolitical boundaries. The Census
Bureau has a Street Index Finder for matching residences to census tracts.
While compiling information on patient residences, centers should also obtain other
information that will be helpful in completing the need/demand assessments such as:
1.3
1.
Information regarding the age/sex distribution of patients.
2.
Information regarding patient income and family size (or sliding fee scale
information).
3.
Information regarding patient payment source.
4.
Information regarding those other patient characteristics that many
influence service utilization and will be useful information for strategic
planning, such as age, sex, race or ethnicity.
5.
Information regarding health status problems.
METHOD C – RETROSPECTIVE RANDOM SAMPLING
This method is a means by which summary information regarding patient
residences can be obtained through sampling of a center’s patient records. The
objective of this method is to obtain information on a sufficient number of patients
to be able to generalize to the center’s entire patient population. Centers with less
than 2,000 records should sample at least 100 records. Center with more than 2,000
records should sample at least 200 records.
Any set of patient files can be used if they contain the required information. (To
avoid bias in the sampling of the records, the patient files should not be organized
by patient characteristics. An alphabetic or numeric ordering is preferred.) Once
the patient record system to be sampled has been chosen, procedures for conducting
the records sampling should be as follows:
1.
Determine the manner in which sampling will be conducted. This total should be
divided by the number of records to be sampled to determine which records should
be pulled.
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EXAMPLE:
1,200
divided by
Patient records
on file
2.
100
=
Number of
records to be
sampled
12
Record selection count
(e.g. every 12th record to
be pulled)
Start by randomly selecting a number for the first record selection. For the
example above you might start with any number from 1 to 12, such as 3. (This was
chosen from a random number table.)
Example:
Pull the third record and compile the necessary information. Continue pulling
every 12th record.
3.
Every sampled record must meet the selection criteria: 1) patients must have
been seen in the last year and 2) sufficient information must be available for
the need/demand assessment. If a record does not meet these criteria, the
next record in the file should be pulled until an eligible record is found.
Center record systems are often organized by family. Information on patient
origins can be obtained by using any household member. If the patient
origin study is also being used to profile the age/sex distribution of center
patients, attention should be given to the selection of patient records. To
avoid over selection of the heads of household, centers should choose the
second, third, or fourth household) and then continue counting records from
this eligible record. When the end of the record system is reached, the count
of records should begin again at the start of the record file if a sufficient
number of records have not yet been sampled.
4.
A count should be maintained of those records found to be ineligible for the
sample. This information should be presented in the need/demand
assessment.
5.
The information required for the need/demand assessment should be
recorded on an index card (as displayed for Method A).
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