Strength
- Presence of concurrent control group
Tai Chi group is compared to the combined exercise group. This reduces the risk of bias by using only the patients (e.g., comparing before and after) as control.Using non-concurrent controls, such as solely comparing the same patients before and after treatment or using external controls (e.g., historical data), increases the risk of bias.
Jacqueline French, Lost in a jungle of evidence: we need a compass - Presence of Non-Exercise Baseline
A non-exercise baseline is provided in the study to directly quantify the benefits of Tai Chi in managing Parkinson's disease. This allows for a clear comparison of the improvements resulting from Tai Chi practice. - Reasonable statistical analysis
The study acknowledges the small sample size of the study; Wilcoxon Signed-Rank Test, suitable for small sample sizes, was used as an alternative to the paired t-test.
Weakness
- Unclear primary outcomes
The study lists various outcomes, including functional fitness, QoL, and depression. However, it is unclear whether a single primary outcome was pre-specified. This could lead to bias and drawing false conclusions by testing every possible variable until one is statistically significant. - Lack concealed and randomised allocation
Due to low initial sample size, randomised allocation is not possible, which makes the study potentially have a high risk of bias. - Lack of support on control group choices
The article does not provide direct evidence for the benefits of combined exercise, which includes rhythmic movements with modified folk dancing and stepping exercises, followed by elastic-band exercises.
An in-depth literature review is needed to provide robust reasoning for the choices. - Lack of detailed inclusion/exclusion criteria
The article attempts to use a more extensive standard for defining Parkinson's disease (PD) (Ref. 15) compared to the Hoehn and Yahr scale. However, although this standard is mentioned, the inclusion criteria lack quantifiable variables needed to determine the severity of the PD patients accepted into the study. While acceptable, more detailed criteria would strengthen the study design."The patients with PD who were recruited from a university hospital to take part in this study had all been under stable management for more than 6 months. They were diagnosed by movement specialists based on clinical criteria. Patients with mild-to-moderate PD were recruited (n=36), while those with severe motor complications, dementia, or psychiatric symptoms that would prevent participating in an exercise program regularly were excluded."
- Unmasked
Assessors collecting the study outcome measures are not blinded and based on per-protocol analysis, which could have biased the results, especially if the outcome is subjective, such as quality of life or depression scores. - Lack of Uncertainty Analysis
According to the definition of uncertainties from the Guide to the Expression of Uncertainty in Measurement (GUM).The article primarily discusses Type A uncertainties evaluated using statistical methods related to the analysis of variance. However, it does not address Type B uncertainties, especially those associated with the measuring equipment. This is especially significant when multiple inputs from different devices are needed to produce a final measurement.To enhance the evaluation of the results' reliability, a more comprehensive analysis of uncertainties should be conducted and included in the article.
Examples of sources of Type B uncertainties:
- Human error in the calibration procedures for the measuring instruments.
- Errors associated with the measuring instruments, as specified by the manufacturer.
- Limitations in the presentation of digital measurements caused by rounding up or down.
- Low completeness of follow-up, addressed with reasonable solution
75% of participants completed the assigned interventions, increasing the risk of confounding differences between Tai Chi and control groups. The reason is that the last outcome assessment of patients who dropped out is compared with that of those who remained in the study, creating an unfair comparison due to the time difference between assessments.To address this, the research team chose to remove dropouts from the analysis. However, this solution introduced new challenges, as it further reduced the already small sample size and significantly impacted diversity, particularly since most of the dropouts were male. - Small sample size with all female
The study included only 23 female participants, limiting the generalizability of the results. This raises doubts about whether the findings can be reliably applied to the broader population, particularly regarding gender representation. - Unclear and confusing interpretation of results
"The parkinsonian symptoms had not improved significantly in any group after the intervention. Longer interventions are needed to reveal any benefits of exercise programs on parkinsonian symptoms. However, several studies have demonstrated an improvement in the UPDRS score after 4-6 weeks of intervention. Unfortunately, these positive results were taken from the intensive interventions in rehabilitation units, and subsequently declined between 6 weeks and 6 months after the intervention. These findings suggest that it is important for patients to be satisfied with the intervention program and to enjoy it, thereby noticing the difference that it makes to their lives."
The statement is misleading because there is insufficient evidence to support the claim that patient satisfaction directly affects improvements in Parkinsonian symptoms. While the paragraph suggests that patient enjoyment and satisfaction with the intervention program are important, the actual results show no significant improvement in Parkinsonian symptoms after the intervention.