We return again with a
new article to appraise in order to consider usefulness when making decisions
with our patients.
When examining research evidence
regarding treatment effectiveness we often find contradictory messages and
evidence pointing in different directions, this can prove to be a confusing
process. This is especially true when considering
conditions affecting the shoulder region where inconsistencies in terminology
and diagnostic criteria for conditions
such as subacromial impingement syndrome (SAIS), can make comparisons between
studies even more difficult.
Well, today we bring up a
follow-up article with a 10 year follow-up comparing a surgical approach versus a
conservative approach in patients diagnosed SAIS:
Subacromial Decompression Yields a Better Clinical Outcome Than
Therapy Alone: A Prospective Randomized Study of Patients With a Minimum
10-Year Follow-up. Am J Sports Med. May 2018; 46 (6): 1397-140
This is a prospective RCT with a
10-year follow-up; the objective was to compare the results obtained in
patients diagnosed with SAIS treated with subacromial decompression (open or arthroscopic surgery) or with
physiotherapy according to the Bohmer protocol.
Patients with subacromial pain
that persisted after conservative therapy (unstructured physiotherapy,
non-steroidal anti-inflammatory drugs, and local injection of corticosteroids)
who were referred to an orthopeadic department from primary care units were
recruited. After recruiting 95 consecutive patients with SAIS, 87 patients met
the inclusion criteria and gave their written consent. The inclusion criteria
were subacromial pain for at least 6 months. The exclusion criteria were
diabetes mellitus, neurological or spinal disorder of any nature, radiographic
OA, the presence of chronic joint disorders (e.g. rheumatoid arthritis), full thickness rupture of the rotator cuff, and SAIS stage III.
The patients were randomized into three groups; open acromioplasty (open surgery group [OSG]), arthroscopic acromioplasty
(arthroscopic surgery group [ASG]) or non-surgical treatment (physical therapy
group [PTG]). The details of the treatments are as follows:
•
Open surgery: The procedure was performed
according Rockwood and Lyons.
•
Arthroscopic Surgery: Arthroscopic subacromial
decompression was performed according to Ellman.
•
Non-surgical treatment: The PTG received treatment
according to the method described by Bohmer.
The clinical evaluation measures
were: The Constant score, SF-36, Watson and Sonnabend score, range of
movement in terms of active elevation and internal rotation, and strength
in abduction.
In addition, ultrasound and radiographic examinations were
evaluated at the beginning of the study and during follow-up.
The authors hypothesized that
after 10 years, patients who had undergone acromioplasty
would have a better clinical outcome and a lower risk of developing ruptures of
the rotator cuff and osteoarthritis (OA) compared to those treated with the physiotherapy programme.
The results of the study through
the 10-year follow-up are reported as statistically significant differences in favour of the surgical interventions in the
active range of motion measurements, muscular strength and Constant score. No
statistically significant differences were found in the Watson and Sonnabend
scores, SF-36, and in the radiographic and ultrasound assessments.
As with many studies, there are limitations that need to be considered. For the purpose of this blog we will focus on the following:
1. Sample
size - statistical power - attrition
2. Difference
in the baseline characteristics between the compared groups
Sample size - statistical power -
attrition:
The authors describe in the
METHODS section that "The study design was planned to include 40 patients
in each treatment group" and that "The estimated sample size was 36
patients per group" but then they add that "the study was
closed after recruiting 87 patients (GSO, n = 24, ASG, n = 29, PTG, n =
34)". In other words, the study required 108 patients
to to have adequate power to detect a difference. Small sample
sizes are generally associated with an increase risk of type II error (not
finding a significant different when one exists) due to a lack of statistical
power to detect a difference. Since a
significant difference was found between the surgical and physiotherapy groups,
this is less of a concern in this study although in the 10-year projection,
there were some results that did not reach significance, which could be explained by the small sample size. As discussed in a previous blog (http://research4physiotherapists.blogspot.com/2018/01/critical-appraisal-of-rct-january-2018.html)
a small sample size is not only a concern from the perspective of generalisability
but also risks false positive findings. Given the size of the three randomised
groups in this RCT this is a concern with this study.
Added to this, during the follow-up, a 38% attrition was observed in the
open surgical treatment group, and an overall attrition of 24.2% of the study
subjects. This may be expected in a 10-year follow-up study, but these factors
should be considered when constructing the research design and consideration given for strategies to account for missing data.
Difference in baseline
characteristics between the groups compared:
As we have seen previously in
other blog posts
(http://research4physiotherapists.blogspot.com/2016/12/the-randomised-controlled-trial.html)
one of the safest ways to distribute the characteristics of subjects equally
between the different treatment groups in intervention studies, both in known
and unknown characteristics is through randomization. So
through the rules of chance, we can be sure that the groups are comparable to
each other, and attribute any differences in the results, to the intervention
that is being studied. In the first instance, the authors state that the groups
in the baseline were comparable, however, in a more careful analysis, consider
the following: when observing the duration of the symptoms of the subjects
assigned to each treatment group, 17 individuals ( 55%) belonging to the
physiotherapy treatment group showed a duration of their symptoms greater than
36 months, more than double that of the 8 present in the arthroscopic surgery
group, and much higher than the open surgery group (11 people). ). This means
that the groups that are compared are different even before they are exposed to
the treatment groups. Thus we cannot be sure that the differences found between the
surgical intervention groups and the physiotherapy treatment group at 10 years
are not influenced by these, and other unknown, differences.
Conclusions:
The strengths of the study included a randomised comparison and
longer-term follow-up. However, the results should be interpreted with caution because
of concerns about the sample size, and risk of chance findings, as well as
baseline differences in the treatment groups in relation to important
prognostic factors.
These findings should also be considered in the context of the recent
CSAW randomised controlled trial (https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)32457-1/fulltext)
and a systematic review comparing surgery with programmes incorporating
physiotherapist-led exercise (https://www.tandfonline.com/doi/abs/10.3109/09638288.2014.907364)
and also one other RCT with 10-year follow-up that reported no difference
between surgery and a programme incorporating physiotherapist-led exercise (https://www.ncbi.nlm.nih.gov/pubmed/28566400).
Tomas Parraguez, Brian Cho, Paul Regan, Chris Littlewood, Sijmen Hacquebord
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