Friday, 27 April 2018

Critical Appraisal of a RCT (April 2018)

Critical appraisal of a randomised controlled trial (RCT)

This month’s blog will focus on a RCT aiming to evaluate the effect of adding dry needling to an exercise programme for people with subacromial pain syndrome; Arias-Buría et al. (2017). A recent systematic review has recognized the low quality research evidence that has been conducted in relation to musculoskeletal conditions and dry needling to date and concluded that although dry needling appears to be superior to no treatment or sham, there is no difference when compared to other physical therapy treatments (1). Hence, given the low-quality of the evidence base and the resultant uncertainty, there appears to be a case for a high-quality, adequately powered RCT in this clinical area.

Arias-Buria et al (2017). Exercises and Dry Needling for Subacromial Pain Syndrome: A Randomized Parallel Group Trial. The Journal of Pain, 18(1), 11-18
The purpose of the study was to examine whether the addition of trigger point dry needling (TrP-DN) to an exercise programme was more effective than exercises alone in the treatment of subacromial pain syndrome (SAPS) over 12 months.

Patients were included in this RCT according to the following criteria:

·      - Unilateral non-traumatic shoulder pain
·      - Pain for at least 3 months
·      - Scoring minimum of 4 points on an 11-point numeric scale.

SAPS was diagnosed based on the presence of a painful arc and two positive findings on any of the following tests: Hawkins-kennedy, Neer, Empty can, Drop arm, and Lift-off tests.

A total of 50 patients were randomized; 25 to the trigger point dry needling plus exercise (TrP-DN+exercise) and 25 to the exercise alone group. Both groups received the same exercise program consisting of three exercises focusing on the supraspinatus, infraspinatus, and scapular stabilizers. Participants were instructed to perform three sets of 12 repetitions with a slow eccentric phase. The program was to be done twice per day for a period of five weeks. A supervising physiotherapist taught the program in the first session and monitored in the subsequent four sessions. 

During the second and fourth sessions, the TrP-DN + exercise group received trigger point dry needling in addition to performing the exercise intervention detailed above. Identification of painful trigger points was left to the discretion of the treating physiotherapist.  The physiotherapist was experienced in the application of trigger point dry needling.

The primary clinical outcome for the RCT was the Disabilities of the Arm Shoulder and Hand questionnaire (DASH) and the secondary outcome was an 11-point Numeric Pain Rating Scale (NPRS) on a 0 to 10 scale. Outcome data were assessed at baseline, one-week and, three, six, and 12 months following the intervention period.

The RCT found no significant differences in NPRS scores between groups at any of the time points. However, in contrast, the RCT reported clinically significant differences between the groups with regards to DASH scores at all follow-up time points. Hence, the authors concluded that the addition of TrP-DN + exercise was more effective than exercise alone for patients with SAPS.

Strengths of this RCT include a pre-registered protocol, a relevant clinical question and appropriate research decision, including adequate randomization processes and appropriate outcome measures.

For the purpose of this blog, we have selected two points for further discussion:

1. The discrepancy between DASH and NPRS scores
2. The sample size and setting

Discrepancy between DASH and NPRS:

One interesting finding from this RCT is the discrepant finding between the DASH and NPRS outcomes, i.e. no between-group differences in relation to the NPRS but clinically significant differences between groups in relation to the DASH score. This is interesting because pain and disability have demonstrated strong correlations and often exhibit direct relationships (2).

We were interested to see if this discrepancy existed in other trials to better understand if this discrepancy between DASH scores and pain was unique to this trial. A brief literature search identified other trials that also used the DASH to measure functional outcome where the primary outcome measure was also pain (VAS or NPRS) at different time points. A critique for each trial is beyond the scope of this present blog, however, we were interested to see if this discrepancy between VAS and DASH was consistent among the current literature base.

A RCT by Lombardi et al (3) compared progressive resistance training against a waiting list control for the treatment of shoulder pain. They reported significant decreases in VAS at rest and movement at the 2-month follow up with an associated decrease in DASH 2 (laborious function) and DASH 3 (activities of daily living) scores in favour of the intervention group. In this RCT, DASH scores were positively correlated with decreases in pain at rest and movement at all time points.

This same trend was also observed in the following RCTS:

Simsek et al (4) compared the addition of kinesio-taping to an exercise program versus the exercise program alone on shoulder pain and function. Improvements in night pain and pain with activity favored the intervention group and also showed a correlation with improved scores on the DASH at the final follow-up, 2 weeks after treatment.

Bron et al (5) reported on the treatment of identified TrPs using manual compression, stretching, and cold application with stretching in addition to ergonomic advice and a supplementary home exercise program. This was compared with a wait-and-see group. The authors reported improvements in pain on movement (VAS-P1), average pain over the past week (VAS-P2), and worst pain over the last week (VAS-P3) with associated decreases in the DASH at the final follow-up point; taken at 12 weeks. No significant differences were found at the first follow-up (6 weeks) in either DASH or VAS.

Zhang et al (6) compared the addition of contralateral manual acupuncture versus exercise alone. VAS scores consistently favored the experimental group at all time points (2 weeks, 4 weeks, 8 weeks, and 16 weeks) with associated improvements in DASH.

It seems that this discrepancy in the pain score and functional outcome reported by Arias-Buría et al. (2017) has not been reported before across many RCTs. Hence, the findings appear unique and thus warrant further investigation to confirm or reject what might be a chance finding.

Author Response:
This is a good point for discussion. We believe that there are no really discrepancies between NPRS and DASH since both outcomes, pain and disability cover different aspects of the patient`s spectrum. In fact, looking the variables at the beginning of the trial, pain and disability have a strong correlation. The results of our study support that both outcomes improve in a similar manner, but the only difference is that patients receiving dry needling exhibit better improvements in self-reported function. We believe it should be not considered as discrepancy, since we believe that pain and function do not always evolve in a similar manner. In fact, this is commonly see this in clinical practice, patients with high levels of pain report levels of related-disability not correlated with the levels of pain, and opposite. We completely agree that these findings should be replicated and studies in future studies.

Sample size and setting

Sample size is an issue covered in previous blogs (here and here) so we will not discuss further in relation to this RCT but this limitation remains relevant.

Furthermore, as the authors of the RCT reflect, as well as the small sample size, a further issue is that all participants were recruited from a single centre. This does limit generalizability. Characteristics present in a group of patients that present in one centre may not accurately reflect those in other areas. Cultural perceptions and individual experiences seem to play heavily into pain and disability (7, 8, 9).


Overall this RCT has many strengths. However, the discrepant findings between DASH and NPRS outcomes and the small sample size drawn from one centre give cause for caution when considering the relevance of these findings for clinical practice. This finding would need replicating in a larger, multi-site RCT before we could recommend implementing this approach in clinical practice with confidence.

Author Response:
We agree that we need multicenter studies including different therapists in different countries for better extrapolation of the results.


Thanks for reading, hope it was useful; thoughts gratefully received.

Brian Cho, Paul Regan, Chris Littlewood, Tomas Parraguez, Sijmen Hacquebord, Fedde van Hees


[1] Gattie, E., Cleland, J. A., & Snodgrass, S. (2017). The effectiveness of trigger point dry needling for musculoskeletal conditions by physical therapists: A systematic review and meta-analysis. journal of orthopaedic & sports physical therapy47(3), 133-149.

[2] Kromer, T. O., Sieben, J. M., de Bie, R. A., & Bastiaenen, C. H. (2014). Influence of fear-avoidance beliefs on disability in patients with subacromial shoulder pain in primary care: a secondary analysis. Physical therapy94(12), 1775-1784.

[3] Lombardi, I., Magri, A. G., Fleury, A. M., Da Silva, A. C., & Natour, J. (2008). Progressive resistance training in patients with shoulder impingement syndrome: a randomized controlled trial. Arthritis Care & Research59(5), 615-622.

[4] Şimşek, H. H., Balki, S., Keklik, S. S., Öztürk, H., & Elden, H. (2013). Does Kinesio taping in addition to exercise therapy improve the outcomes in subacromial impingement syndrome? A randomized, double-blind, controlled clinical trial. Acta orthopaedica et traumatologica turcica47(2), 104-110.

[5] Bron, C., De Gast, A., Dommerholt, J., Stegenga, B., Wensing, M., & Oostendorp, R. A. (2011). Treatment of myofascial trigger points in patients with chronic shoulder pain: a randomized, controlled trial. BMC medicine9(1), 8.

[6] Zhang, H., Sun, J., Wang, C., Yu, C., Wang, W., Zhang, M., ... & Wan, Y. (2016). Randomised controlled trial of contralateral manual acupuncture for the relief of chronic shoulder pain. Acupuncture in Medicine34(3), 164-170.

[7] Campbell, C. M., & Edwards, R. R. (2012). Ethnic differences in pain and pain management. Pain management2(3), 219-230.

[8] Pillay, T., van Zyl, H. A., & Blackbeard, D. (2014). Chronic pain perception and cultural experience. Procedia-Social and behavioral sciences113, 151-160.

[9] Peacock, S., & Patel, S. (2008). Cultural influences on pain. Reviews in pain1(2), 6-9.

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