Physical therapists develop prognoses to predict future outcomes for patients, including risks of future problems and results of interventions. Evidence about prognostic risk factors comes from studies evaluating samples of patients. Higher quality studies have more valid results by clearly defining patients, collecting complete outcome data, and confirming findings in new samples. Prognostic research identifies factors correlated with outcomes using statistical analyses.

1. APPRAISING EVIDENCE ABOUT
PROGNOSTIC (RISK) FACTORS

2. INTRODUCTION
Prognosis:
 It is the process of predicting the future about a
patient client condition.
 Physical therapist develop prognoses about :
1. The risk of developing a future problem
2. The ultimate outcome of an impairment in body
structures or function, an activity limitation or a
participation restriction.
3. The result of physical therapy interventions.

3.  Prognostic estimates are formulated in response
to questions posed by patientsclients and their
families, as well as to indicate the response of
the therapist’s plan of care.
 In both instances the predicted outcome includes
a time frame for its development to satisfy
patientclient expectations as well as to address
payer interests with respect to the duration and
intensity of the physical therapy episode of care.

4. Risk of a future adverse event:
 Physical therapists concerns about the risk for
developing future problems generally are focused on
patients for whom a primary medical diagnosis or
impairment already is established
 Examples for potential problems:
1. Skin breakdown as a result of sensation loss( as in
DM and stroke) and immobility ( as SCI and casting)
2. Re injury with return to work or athletic activities
following joint sprain and muscle strain
3. Falls as a result of neurological insult ( as in stroke
or brain injury)

5.  Physical therapists formulate prognoses related to
the ultimate outcome of movement related
impairments in body structures and functions, activity
limitations, and participations restrictions.
 Prognostic questions regarding ultimate outcomes
are
1. Will I always need oxygen for activity?
2. Will I walk without a walker again?
3. Will my shoulder always be painful when I pitch?
4. Will my child be able to attend school like other
children?
 These are the questions raised by patients and
caregivers as well as by students and professionals
with limited experience with various patient

6. Results from physical therapy interventions
 Predictions about the results produced by
interventions are reflected in the goals physical
therapist write for their patientsclients.
 In addition this information is tied to a timeline such
as the no. of days, weeks or visits that is anticipated
to achieve the specified outcomes.
 The therapist’s challenge is to consider the likelihood
of achievement, within the specified time line, of the
outcomes identified for a given patient/client.
 Eg : a patient, ability to learn a home ex’s program
prior to hospital discharge following total knee
arthroplasty may depend on the individual's cognitive
abilities and support from family or caregivers

7. Elements of prognosis
 Three elements
1. The outcome(or outcomes) that are possible
2. The likelihood that the outcome(or outcomes will) occur
3. The frame required for their achievement

8. Study Credibility
 Evidence pertaining to prognostic factors first should
be evaluated with an assessment of its research
validity.
 Higher research validity provides greater confidence
that a study’s findings are reasonably free from bias.
In other words, the result are believable.

9.  Did the investigators operationally define the sample in
their study?
 One of the first concerns investigators must address with
respect to their sample is its definition
 Clearly articulated inclusion and exclusion criteria should
be used to ensure that subject fit the definition of
individual who have, or who are at risk for, the outcome of
interest.
 Where the subjects representative of the population from
which they were drawn ?
 The issue of representativeness pertains to the degree to
which investigators where able to capture all eligible
subjects during the time frame of the study.

10.  Did all subjects enter the study at the same
(preferably early ) stage of their condition?
 This question is particularly salient for longitudinal cohort
design designs. Investigators must determine at what
point patient should be gathered for study. This decision
depends in part on the nature of the outcome of interest
and in part on the research question.
 Was the study time frame long enough to capture the
outcomes of interest?
the length of follow up time of a study will depend on
which outcomes or events are being anticipated. The time
frame identified must be long enough for the human body
to achieve the outcome from a physiology or
psychological stand point. If the time is too short, then a
possible outcome will be missed.

11.  Did the investigators collect outcome data from all
the subjects enrolled in the study?
the ability to capture the outcomes of all the
subjects is important because attrition for any reason
may provide a skewed representation of which
outcomes occurred and when. Ideally, investigators
will be able to determine what happened to subjects
who left the study in order to evaluate whether the
outcomes were truly different than for those who
remained. Differences between subjects who
remained and subjects who dropped out indicate that
bias likely has been introduced to the prognostic
estimates.

12.  Were outcome criteria operationally defined?
this question addresses the validity of the measures
used to capture the outcomes of interest. A clear
definition of the outcome is necessary to avoid
misidentification. Investigators should articulate specific
clinical and/or testing criteria prior to the start of data
collection.
 Were the individuals collecting the outcome measures
masked ( or blinded) to the status of prognostic factors in
each subjects?
ideally, those measuring the outcomes will be masked, or
ignorant of the subjects prognostic (risk) factor. Prior
knowledge of subjects status may introduce teaser bias
into the study because expectations about the outcomes
may influence application and interpretation of the
measure used to capture them.

13.  Does the sample include subgroups of patients for
whom prognostic estimates will differ? If so, did the
investigators conduct separate subgroup analyses or
statistically adjust for these different prognostic
factors?
A subgroup is a smaller group of subjects who have
a characteristic that have a characteristic that
distinguishes them from the larger sample. This
characteristic is anticipated to influence the outcome
of interest such that a different prognostic estimate is
likely to be identified.

14.  Did investigators confirm their findings with a new
set of subjects?
This question alludes to the possibility that the
research findings regarding prognostic(risk) factors
occurred due to unique attributes of the sample.
Repeating the study on a second set of subjects who
match the inclusion and exclusion criteria outlined for
the first set provides an opportunity to evaluate
whether the same predictive factors are present.

15. STUDY RESULT
 Prognostic research uses both descriptive statics, as
well as tests of relationships to identify
prognostic(risk) factors.

16. THE STATISTICAL IMPORTANCE OF STUDY
RESULT
 In addition to the correlation coefficients, odds ratios,
relative risk, and hazard ratios reported in studies,
investigators also provide information to determine
the “meaningfulness” or potential importance of their
result. The two primary ways to convey potential
importance are via the p value and the confidence
interval. A p value indicates the probability that the
result obtained occurred due to chance. The smaller
the p value (eg., <0.005), the more important the
result is statistically because the role of chance is so
diminished although not eliminated.

17. EVIDENCE AND THE PATIENT/ CLIENT
 As with all evidence, a study about prognostic (risk)
factors must be examined to determine if the
subjects included resembles closely enough the
patient/ client to whom the results may be applied.
 The unique twist to the use of prognostic evidence is
the degree to which it will influence what therapists
will tell their patients / clients about their future, as
well as how treatment planning will be influenced, if
at all.

20. SUMMARY
 Prognosis is the process of predicting a future
outcome for a patient / client.
 Evidence about prognostic (risk) factors for
outcomes relevant to physical therapist is limited but
should be evaluated when possible to improve the
prognostic estimation process.