Dear Editor,

We have read the article by Wang, Sizhong and colleagues, entitled, “The immediate effects of mobilization with movement on shoulder range of motion and pain in patients with rotator cuffrelated shoulder pain: A randomized controlled trial (Evolution Trial)”1 The authors had explained the immediate effect of mobilization with movement (MWM) in improving the angular onset of pain after 3 sets of 10 repetitions of MWM in patients with RCRSP. However, we would like to bring the author’s attention to critical points that may benefit the reader’s comprehensibility from additional discussion. In methodology, the author recruited participants aged 18–75 years with RCRSP. This could complicate or introduce variability in the study's findings, due to the increased rate of degeneration with age.2 Furthermore, As shown by the BESS (British Elbow and Shoulder Society) guidelines that were used in this study, most people with rotator cuff tendinopathy are usually between 35 and 75 years old.3 Therefore, having younger individuals in this study may have added some variability to the study results.

Secondly, authors have reported baseline demographic data in Table 1 per CONSORT, but baseline matching between the two groups would confirm the treatment effect and confer greater credibility. The study had included participants with both acute and chronic pain, with different treatment/ medication status, which could affect the matching and act as covariates.

Also, for RCRSP participants, initial patient-reported data using the Patient-Specific Functional Scale (PSFS) and the Shoulder Pain and Disability Index (SPADI) were collected, but their need is not justified. Though authors have discussed about levels of psychological distress of patients, they did not report on activities that most of the participants find difficult.

(as recorded by PSFS) and levels of pain with disability (SPADI) in these cases. As the title. suggests, the patient's response during the evolution trial is crucial for interpreting the intervention.4 Thirdly, in Data Analysis, whether the data are normally distributed and which normality test is used are not mentioned. Further, sample size estimation was based on a standard deviation of 19 degrees from a previous study or on an assumption. The reference study was an oral presentation at a conference proceeding, and the supporting text and/or data set are not available.5 As a result, the sample size calculation cannot be verified and was not replicable. Finally, although the authors used a 5% dropout rate, 4 participants in the experimental group dropped out during the week-long protocol. As the intervention was well accepted by patients at the beginning, the authors have not reported any harms, stopping guidelines or reasons for dropouts.4 When participants have not completed the intervention, the internal validity of the study is compromised. Moreover, the analysis of the missing data needs clarification.6The study could have benefited from the Use of stratified analysis in quantifying the results with reference to the heterogeneous population of RCRSP for a broad age group.