Efficacy of repeat TFESIs for radicular pain due to HNP
Introduction
Corticosteroids are felt to be effective treatment for radicular pain via both antiinflammatory and neural stabilization mechanisms. Epidural injections have been
purported to be potentially effective via the deposition of the steroid within the spinal
canal, closer to the site of inflammation than would be achieved by an intra-muscular or
systemic route of administration. However, interlaminar lumbar epidural steroid
injection achieved no better results than sham injection. Injection into the caudal epidural
space achieved no greater success rates than caudal injection of local anesthetic.
TFESIs are more effective than interlaminar injection of steroids in reducing pain
disability, and surgery. TFESIs are superior at one month to intramuscular steroid, and
transforaminal saline or local anesthetic. However, over time the proportion of patients
with continued relief diminishes, and at one year, the relief provided by TFESIs is no
greater than that of intramuscular steroid, or transforaminal saline or local anesthetic. It is
not known whether additional TFESIs achieve a larger or more durable treatment effect.
The present study is designed to assess if repeating transforaminal injections of steroid
provides more durable and/or greater relief than a single injection. This study will also
assess whether providing restorative injections (up to five total injections per year) if pain
relapses after previous complete relief maintains the benefit provided by the steroid
injections.
The three null hypotheses are:
Pursuing up to three TFESIs in patients who do not initially respond is neither effective
nor efficient.
Perfecting a partial response is neither effective nor efficient.
Patients who initially respond do not respond to restorative treatment.
Methods
This protocol will employ the inclusion/exclusion criteria from Ghahreman et al and
subjects will be randomized to one of three groups:
In Group 1, the initial injection will not have produced any clinical benefit. These
patients will, by protocol, receive two additional injections, at approximately two week
intervals, unless a prior injection (in this group, the second injection) resulted in complete
pain relief. A repeat injection is to be performed at follow-up in a manner consistent with
the initial procedure.
In Group 2, if the patient feels that the initial treatment resulted in noticeable
improvement in their pain or function, but not complete relief, a follow-up evaluation is
to be conducted within approximately two weeks of the previous treatment. A repeat
injection is to be performed at this follow-up in a manner consistent with the initial
procedure. Patients are entitled to have repeat injections, up to three total injections,
during the one-year course of the study, provided the prior injection resulted in some
degree of benefit, in the opinion of the patient. Patients in this group who are
experiencing complete relief of radicular pain at the time of follow-up, and in whom no
radicular pain is precipitated during exam, will not receive a repeat procedure. However,
if after initial complete relief, the previous radicular pain recurs prior to the one-year
follow-up, additional restoring injections may be performed, though not to exceed five
total injections per year.
In Group 3, these patients will be evaluated at six weeks (?vs two or four weeks) after
their injection for completion of outcome measures. However, if after initial complete
relief, the previous radicular pain recurs prior to the one-year follow-up, additional
restoring injections may be performed, though not to exceed five total injections per year.
Six weeks after initial treatment, which could include up to a maximum of three
injections, patients will undergo a formal follow-up at which time the outcome
instruments will be administered. Patients will then be assessed at three, six, and 12
months, or until relief of pain ceases, after initial complete relief. If the radicular pain is
completely extinguished prior to three injections, but the relief then ceases, patients in the
repeat injection group are entitled to re-enter the treatment protocol for a restoring
injection, but only to a maximum of five injections in the one-year duration of the study.
Upon re-entry, the patients may have repeated injections, up to five total injections, or
until the pain is either extinguished, or fails to respond progressively to the prior
restorative injection.
Outcome measures:
VAS or NPR
ODI and SF36
subject self-report of having returned to selected ADL’s
use of additional healthcare (repeat TFESIs)
Excellent response defined as:
1. reduction in pain, by more than the MCIC, plus
2. improvement in function, by more than the MCIC, plus
3. restoration of > 2/4 desired activities,
4. patient does not want or need repeat injection, and does not require any other health
care for their radicular pain beyond self-management, i.e. over the counter medication
and home exercises.
Good (acceptable) response defined as:
Two or more of the above four endpoints
Treatment failure defined as:
1. need for repeat treatment
2. continuing to take prescription medications
3. still seeking care
4. waiting for surgery or scheduled to undergo surgery.
For statistical analysis:
The initially successful group will be the benchmark; e.g. 45% of inception group get a
good initial response, after one injection. Subsequently they cost, say, three injections to
maintain outcome for one year.
In comparison, only a tiny proportion of patients get a good outcome after three
injections; and the duration of lasting effect is significantly less than the benchmark.
Perfecting the response works in only a tiny proportion of patients, but their subsequent
duration of outcome is like that of the benchmark.
The proportions of patients falling into each group will be compared using 95%
confidence intervals.
The results will look like this.
achievement
phase
restoration
phase
1.00
1.00
P
1.00
duration of effect
repeat
T
I
one year
T: three injection group
P: pursue perfection of response group
I: initially successful group
Firstly, the study measures the number, and therefore the proportion, of patients:
1. who achieve a good outcome following a series of three injections despite initial
response;
2. who achieve a good outcome from trying to perfect a response; and
3. who achieve a good outcome from the first injection.
Secondly, the study measures the number of restorative injections required to maintain
the good outcome, and the median duration of the good outcome, in each group.
The data will show that:
Pursuing up to three injections despite response does not appreciably increase the yield of
treatment, i.e. the proportion of successful outcomes in group T will be low; plus, these
folks will not maintain their response; the yield of restorative injections will be low, and
the duration of response will be short.
Perfecting the response increases the initial yield in very few patients; they may have
lasting relief; but I suspect that they will not be long survivors.
In patients with an initial good response, the response will have a median duration of
three months (spread between one month and up to one year), and a median number of
three injections to maintain the response over a year.
Conclusions intended are:
Pursuing up to three injections is not efficient; it consumes a lot of physician time, to
repeat injections, for so little yield both initially and during the restorative phase.
Perfecting the response seems worthwhile, for the cost of perhaps only one extra injection
in the initial phase.
About 30% of patients who get a TFESI get an initial good response and maintain that
response for one year for the price of three injections per year.