ILLINOIS REGISTER 8857
09
HEALTH FACILITIES PLANNING BOARD
NOTICE OF PROPOSED AMENDMENTS
b) Formula Components
Formulas utilized by HFPB in projecting the need for beds and services can be
categorized as demand based or incidence based need formulas. Each of these
formula types represents a different conceptual outlook and incorporates different
data elements as formula variables.
1) Demand Based Formula. Demand equations utilize the concept that what
has occurred in the past will occur in the future. The formulas utilize
inpatient days of care and population projections as the key data variables.
The first formula step is to establish a utilization to population ratio (use
rate). This ratio basically says that within a population an average number
of inpatient days of care will be generated. This rate is then applied to the
population projection for the same area. This states that if the rate of use
is constant, a future population can be expected to generate an identifiable
number of inpatient days. These projected days are then converted to a
daily census (projected days – 365) and multiplied by an occupancy target.
The projected day figure can be equated to 100% occupancy of service for
which need is projected. An occupancy factor adjustment is applied to
insure that sufficient beds exist to handle days when inpatient admissions
are exceptionally high. This type of formula may also be adjusted by the
application of minimum and maximum use rates in planning areas that
lack facilities or certain types of beds or where a high concentration of
beds and services has caused unnecessary duplication. These rates are
controls and serve to inflate (minimum use rate) or deflate (maximum use
rate) the projected bed need. These rates are established when historical
patterns of use are influenced by a maldistribution of services. By adding
to or subtracting from the number of needed beds, development of new
beds and facilities can be influenced to add beds to underserved areas and
to restrict bed growth in areas of high bed to population ratios.
2) Incidence Based Formula. This type of formula utilizes the incidence
level of a disease or a condition within a population to predict need.
Utilizing national or State rates, the formula predicts the number of
planning area residents who will need hospitalization based on the number
of people who live in the planning area. Utilizing a standard estimate of
how long a patient will be hospitalized, admissions are converted into
patient days. As in the demand formulas, days are then converted to an
average daily census and an occupancy factor adjustment is applied to
obtain area bed need.
