Friday, August 1, 2008

End of this story but the beginning of many more

While Summer Immersion term is over, my project most definitely is not. Over the past few weeks I’ve been spending less and less time in the OR and the clinic and more time behind a computer learning statistical methods and doing statistical analysis. My project has been to use a database created by medical research assistants to determine if there is a correlation between the rate of complications after radical cystectomy and the type of cystectomy being performed (robotic vs. open). The crazy thing is that in all my weeks at Weill I had yet to see an open cystectomy. It seems that Dr. Scherr is somewhat defined for his ability and proficiency with robotic cystectomies. Just yesterday I had my first opportunity to see an open cystectomy, so I popped into the OR to see what my analysis was really evaluating. The surgery definitely seemed more difficult without the magnification of the robotic camera, but the reality is that many surgeons still prefer to perform this surgery open because they are more proficient behind the table rather than at a robotic console. The specific case Dr. Scherr was performing was an open cystectomy because the patient had had a partial nephrectomy before and they knew there would be scar tissue to deal with that they were unaccustomed to with the robot.

I say that my research project is definitely not over for a couple of reasons. First, I will continue to analyze and tweak our model over the next few days to see if I can improve the model fit. We had to use multinomial logistic regression to analyze the data because we are looking at a binary outcome (complication or no complication). Additionally many of our predictor values are ordinal or nominal rather than scalar. The five variables we choose to evaluate (we being a few residents and I) are body mass index (BMI), age, Charlson score, ASA score (American Society of Anesthesiologists score) and the type of cystectomy (robotic or open). I first looked for a basic correlation between the type of cystectomy and occurrence of complications using crosstabulation and Pearson chi-squared tests. This showed that there is a significant correlation between the two, but we needed to ensure that was not just an artifact of other factors. For example we needed to prove that it is not just the younger, leaner, healthier patients that are undergoing robotic cystectomies. To show this more rigorously I needed to use multivariate regression but with these nominal and categorical variables. In the end I think I developed accurate models, but only more time and more critical evaluation by the residents will tell. Secondly this project is far from over because our analysis is limited by the fact that we only have around 200 patients. At first I thought this was more than sufficient, but as I continued to do my analysis and needed to categorize these cases the sub-grouping became ever smaller making statistical analysis very difficult. So this evaluation will just be the foundation that they can build upon in years to come as they continue to have a more robust database of cases.

Finally I just want to remark on the miracle of life. Last Friday Jen and I had a wonderful opportunity to observe a C-section. Not only were the patients gracious at having additional people in the room but the surgeon was also keen to teach us. Before we ever entered the OR he had us read-up on why this patient was having a C-section. This woman had a bicornuate bicollis uterus (which is to say she had a septum in her uterus dividing it in two). A C-section was required and might need to be performed along the length of the uterus rather than at the base because her two uteri are narrower than a standard woman’s uterus. In this case though, they were able to get the baby out of the base of pregnant uterus and could even show us the amazing capability of the uterus to expand with a baby since this woman had one pregnant and one non-pregnant uterus. So not only had we walked in to see a C-section, but we also walked in on a high risk pregnancy that had come to full term with a healthy baby. Additionally this was the first child for these parents and they didn’t know the baby’s sex, so it was a very exciting OR!

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