In total of 50 included studies in that 8 are low risk of bias where 5 studies participants are not blinded. Outcome assessor is blinded in all 8 studies. And in 6 studies therapists are not blinded. And 4 studies data analyst is not blinded.

In total of 50 included studies in that 23 are uncertain risk of bias where 20 studies participants are not blinded. Outcome assessor are not blinded in 9 studies. And in 20 studies therapist is not blinded. And in 22 studies data analysts are not blinded.

In total of 50 included studies in that 19 studies are high risk of bias where all 19 studies participants, outcome assessor, therapist, data analyst none of them are blinded.

Figure 2

In physiotherapy, randomized controlled trials are rarely blinded for all potential critical individuals. In the present study of trials published in high impact journals, 11.3% of included trials participants are blinded, 9.4% of included trials' therapist are blinded, 50.9% of included trial’s outcome assessor are blinded and 7.5% of included trials data analyst are blinded. If none of the key persons are blinded, then risk of bias will be more. In 67.9% of included studies blinding status is described. It might not be acceptable to infer insufficient blinding just from insufficient reporting. Numerous studies show that even when blinding measures have been properly applied, trialists frequently fail to acknowledge them13, 15, 16, 17, 18, 19. However, the possibility of skewed results may be decreased by correct reporting of blinding efforts and discussions about lack of blinding. In the present study, 32.1% of the included studies don’t describe the blinding status of their study. Because of this, it is challenging for readers to evaluate the caliber of the research. In light of our findings, there is a possibility that prior randomized clinical trials of physical therapy interventions may have been biased in that they overestimated the positive effects and understated the negative effects of the experimental interventions under investigation. This is because blinding is a necessary condition for conducting such trials. There may be grounds for suspicion that important participants in an unblinded experiment may, deliberately or unconsciously, fail to identify the interventions' negative consequences. Due to underlying beliefs, a non-blinded trial participant who has a stake in the outcome, such as a physiotherapist with extensive training in a particular physiotherapy intervention, may pay less attention to negative impacts. Similarly, a person who is not blinded but is informed that the physiotherapy intervention is successful and safe may either fail to notice or fail to disclose adverse consequences.

The present study has limitations. First with adequate blinding, we might have overlooked crucial studies, but we chose the wrong journals for that. In contrast to journals with lower journal impact factors, high journal impact factor journals are believed to have lower bias risk. As a result, it's possible that the included studies from the chosen journals understated the actual bias risk associated with a lack of blinding, and that blinding would actually be even less common if studies from journals with lower journal impact factor had also been included. Second Although other intervention fields (such as surgical interventions) may experience analogous blinding issues, we only examined physiotherapy interventions.

One could argue that in a randomized clinical trial, it is difficult or impossible to blind all-important participants20. Participants in pharmaceutical trials may encounter adverse events or not which could compromise their blinding4. Or in surgical trials it is difficult to perform sham interventions for blinding purposes17. It is necessary to discuss whether or not blinding of participants and healthcare providers introduces a bias risk that needs to be mitigated in randomized clinical trials of physiotherapy therapies. Even with this seeming barrier, one can contend that it is reasonable to anticipate bias from non-blinded participants. Research on non-physiotherapy interventions has shown that non-blinded participants may experience and report symptoms differently from those who were blinded due to response bias (when participants report symptoms in a way that they believe will please the researchers) and positive response expectancy from receiving a treatment that was deemed to be superior12. This could induce participants in a randomized clinical trial to (consciously or unconsciously) report exaggerated symptom relief simply because they consider the treatment team or outcome assessors to be compassionate and interested in their well-being. Because of self-confirming response expectancies, it may also result in accurate reports of higher symptom relief. Given their personal stake, therapists would likely anticipate that a particular physiotherapy intervention, for which they are frequently well-trained and closely monitored, will be superior to standard care. If the therapists reveal their allegiance to the participants, this anticipation may affect the participants' outcomes. Given that the anticipation of progress can change therapists' behaviors in ways that impact the quality of the treatment, it may even affect the participants' outcomes even if the therapists do not disclose their loyalty.

It is feasible to plan a physiotherapy trial with the goal of blinding participants and healthcare professionals21. In order to administer blindfolded or non-blinded physiotherapy, the first step would be to randomly assign motivated future therapists with little to no experience to either get blinded or non-blinded training and supervision15. If there are enough therapists involved, it will be feasible to determine whether attempts at blinded physical therapy would result in different intervention effects from physical therapy provided by non-blinded therapists, and whether this would damage the active components of physical therapy15. If no indication of a difference is discovered, the next step would be to create a randomized clinical trial that compared two physiotherapy traditions while making an effort to blind any potential critical individuals22. Of course, such a trial would have its limitations; for instance, it may be impossible to administer the physiotherapy intervention effectively during a trial time while maintaining blinding if it required substantial training of the therapists. Therefore, there is a chance that the findings might be less generalizable due to the lower level of training. Recruitment of participants with little to no prior knowledge of physical therapies may potentially limit generalizability23, 24. Additionally, only trials with a "active" control group might conceivably use the suggested approaches to blind the participants. There is a chance that the participants would recognize the offered care from prior experience if the control group is standard care. However, it could be argued that the advantages of total blindness might not outweigh the restrictions brought on by low generalizability. We feel that blinding of all potential parties should ideally be sought in randomized clinical trials of physiotherapy therapies until data has established that it does not significantly alter the results.

Current study demonstrated the estimate of blinding status in randomized controlled trials in physical therapy interventions. In randomized clinical trials of physiotherapy therapies, blinding of important participants is infrequently reported, and few trialists take into account the bias risk that this may have introduced in studies that were published in journals with high impact factors. There is a chance that earlier randomized clinical trials of physiotherapy interventions in general may have overstated the positive effects and understated the negative consequences of the experimental interventions under investigation. Randomized clinical trials that seek to blind all potential important individuals are required to evaluate the outcomes of physiotherapy therapies. Readers should take the potential ramifications into account when evaluating the study results if blinding cannot be implemented or is not fully reported. The implementation and reporting of blinding status in future randomized clinical trials of physiotherapy therapies should be improved, particularly for trial participants who are readily blinded, such as data managers, the data safety and monitoring committee, statisticians, and decision-makers.