Association between newer glucose-lowering drugs and risk of Parkinson’s dis-ease

 Here is a link to the paper.

In hypothesis testing, the null hypothesis (typically, no association or no effectiveness) is rejected at a chosen level of statistical significance (often 5%). It works roughly like this:

• Choose a null hypothesis (e.d., no association or no effectiveness).
• Compute the expected outcome of the experiment assuming the null hypothesis is true.
• Compare the outcome of the experiment with the expected value under the null hypothesis.
• Compute the probability of observing an outcome at leasst as extreme in difference under the null hypothesis.
• If the probability is les than the chosen level of statistical significance, reject the null hypothesis. Otherwise accept the null hypothesis.

The computed probability is done in a way that reflects sample size. So, no sample size qualification is necessary (given all the requirements of the statistical theory). This suggests that the qualification at the end of the excerpts reflects a misunderstanding of statistics or a belief that the requirements of applying their statistical methods are not met. Of course, if it is the latter, all bets are off.

Here are some excerpts.

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Meta-analysis of Association between Newer Glucose-Lowering Drugs and Risk of Parkinson's Disease

Background

The association between newer classes of glucose-lowering drugs (GLDs) and the risk of Parkinson's disease (PD) remains unclear.

Objective

The aim was to examine the effect of newer GLDs on the risk of PD through a meta-analysis of randomized outcome trials.

Methods

The methods included randomized placebo-controlled outcome trials that reported PD events associated with three newer classes of GLDs (ie, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 receptor agonists, and sodium-glucose co-transporter-2 inhibitors) in participants with or without type 2 diabetes. The pooled odds ratio (OR) and 95% confidence interval (CI) were estimated using Peto's method.

Results

The study included 24 trials involving 33 PD cases among 185,305 participants during a median follow-up of 2.2 years. Newer GLDs were significantly associated with a lower PD risk (OR: 0.50; 95% CI: 0.25–0.98) than placebo.

Conclusion

Newer GLDs may possibly be associated with a decreased risk of PD; however, larger datasets are required to confirm or refute this notion.