How to calculate population prevalence and sample prevalence?

[Steven-ZWQ]

As Table S1 in the original article, both sample prevalence and population prevalence equaled the number of cases divided by the number of controls when data were obtained from a population-based cohort (UK Biobank). The definition of "prevalence" in pleio seems to be different from the terminology in the epidemiology, which may cause ambiguity. I'm not sure whether my understanding is correct. Thanks!

[cuelee]

Yes, it is correct.

We estimated the disease prevalence obtained from a population-based cohort (UK Biobank) as: N case / (N case + N control)

[Steven-ZWQ]

Dear, Dr Lee, Thanks so much. The estimation of disease prevalence (N case / N control) in Table S1 (PMID: 33352115) may mislead readers. I’d like to know how to obtain the sample prevalence, N case / N control as shown in Table S1. It looks like a ratio measure. Thanks again. Sincerely, Wenqiang.

[cuelee]

Yes, you are correct. The prevalence in Table S1 uses case/control ratio. In your analysis, please use case/population instead case-control ratio.

[Steven-ZWQ]

Thanks so much! Is there a difference between sample prevalence and population prevalence?

[cuelee]

With regard to this question, please refer to https://doi.org/10.1002/gepi.21614.

[Steven-ZWQ]

Thanks.