I am doing a prelim analysis for a pilot study I have performed. I will have dedicated stats professionals in the future, but for now I am on my own and need to do some basics.

This is a retrospective chart review of >2000 consecutive patients undergoing any 1 of 3 types of open heart surgeries (lets say operations 0,1,2) in between two predetermined dates at a single hospital.

I am looking for a complication known as diaphragm elevation. There are 3 categorical outcomes. No elevation , Left elevation , and Right Elevation.

I have preoperative demographic data, both categorical (the presence of certain comorbid conditions) and continuous (such as age). I have operative data both categorical (operative approach, type of graft, etc) and continuous (number of grafts, etc). Finally I have outcomes data both categorical (presence/absence of post operative respiratory failure) and continuous (length of stay).

My primary objective is (1) to calculate the incidence of diaphragm elevation for each of the 3 surgery types. This is straightforward.

My secondary objectives include (2) determining any significant associations between pre-operative or operative data and diaphragm elevation and (3) any significant associations between diaphragm elevation and post-operative outcomes.

My question is what statistical tests should I do to achieve 2 and 3? Fisher's exact test for the categorical variables and T-tests for the continuous variables? I am really just looking for guidance on what my general approach should be to this data. I am aware there are tons of limitations in a retrospective cohort review. This is hypothesis generating. Once I have the stats team on board I think they will likely match controls to do a case control analysis but I need to have something to present before this. Ultimately, a prospective study will be performed.

Thank you so so much.

Boomer