Adjusted Chi-square Test for cluster randomized trial

Pooh — Mon, 18 Feb 2019 23:17:29 GMT

Hi, can someone answer my naive question?

I am analyzing a cluster randomized trial conducted in schools. My outcome is binary (improvement in 50% of the tooth sites that showed gingival bleeding outcome at baseline after receiving the intervention vs no improvement). The trial has three arms (2 intervention groups and 1 control group). The unit of analysis was the school child.

For my bivariate analysis, I would like to utilize the Chi-square test, to explore if the proportion of students with my outcome of interest differs by group at baseline. I have read that I need to run an adjusted chi square test (adjusted for ICC), but I can't find the SAS code. The clustering is as follows:

1000 students within 19 primary schools within 9 villages. 3 villages were randomized to group 1 (intervention 1), 3 villages to group 2 (intervention 2) and 3 villages to group 3 (control).

I have created the models and ran a GEE (with the appropriate corrections for low number of clusters) for my multivariate analysis that accounted for the clustering. However, I also want to run a bivariate analysis, to include in my statistical analysis section of the paper. I am facing a roadblock because I can't find the SAS code for an adjusted chi-square test that accounts for the clustering within schools (ICC)

Thank you!

Re: Adjusted Chi-square Test for cluster randomized trial

Watts — Thu, 11 Apr 2019 20:09:11 GMT

One possibility might be a Rao-Scott design-adjusted chi-square test, which accounts for clustering.

PROC SURVEYFREQ provides this test (CHISQ option in the TABLES statement).

Documentation is here:

https://go.documentation.sas.com/?docsetId=statug&docsetTarget=statug_surveyfreq_syntax06.htm&docsetVersion=15.1&locale=en#statug.surveyfreq.sfreqchisq

and

https://go.documentation.sas.com/?docsetId=statug&docsetTarget=statug_surveyfreq_details64.htm&docsetVersion=15.1&locale=en

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Adjusted Chi-square Test for cluster randomized trial

Re: Adjusted Chi-square Test for cluster randomized trial