Reference: Hassan, C., et al., A predictive model identifies patients most likely to have inadequate bowel preparation for colonoscopy. Clin Gastroenterol Hepatol, 2012.10(5): p. 501-6.
A study from Italy on the the factors which are most likely to lead to inadaquate bowel preperation for Colonoscopy.
Results: The patient factors deemed to be predictive of an inadaquate bowel preperation were being over weight, male sex, a high body mass index, older age, previous coloretal surgery, cirrhosis, having Parkison’s disease, having diabaetes and a negative result in a fecal occult test. Among the non-patient risk factors, some of the factors which were deemed to be predictive were the type of bowel preperation regimine , the difference in time between the preperation and the actual colonoscopy (less time is better), and information on the preperation (oral+written info is better than just oral). The authors found a moderate predictive accuracy on a validaiton test set (AUC=0.63). The clinical detection rate of polyps and cancer lesions along with the cecal intubation rate was significantly higher in patients with an adaquate bowel prep vs. an inadaquate bowel prep.
Implications for Practice: It is important that patients undergo an adaquate bowel preperation, and the probability of an adaquate bowel prep can be enhanced if the patient is given both a written and oral information for the bowel prep.
Discussion: Really interesting finds here and very comprehensive to say the least. It is alarming the difference in clinical detection rate for polpys and cancer lesions between adaquate vs. inadaquate bowel preperations. For adaquate bowel preperations, the rate was 41% and for inadaquate bowel preps, the rate was 35% which is a rather significant difference.
Some of the risk factors that came up positive were rather surprising. It is interesting to see that males and those with Parkinson’s and diabates had a higher chance of an inadaquate test. It would be neat to do a follow up explanation on many of the risk factors that came up. It seems like the best bowel prep regimine was the Sennosides. This seemed to be better than the use of any regimines which used the polyethylene glycol (PEG) solution or sodium phosphate.
Commentary on Statistics and Study Design: The study design and presentation was very good. This is an exploratory based perspective study. In any type of exploratory based study, there are often many variables at play in the model building step, and the investigators handled them well here. I particularly like how the authors included the results of both the uni-variate and multi-variate analysis for the logistic regression. It is always helpful to see the results of both, because it gives the reader a sense of what variables are independently and also dependently associated with the outcome variable. The multi-variate results also tell you which variables (or risk factors) would be most likely to be associated with the outcome variable. The only suggestion I have for the authors here would be to also include the odds ratios for the uni-variate analysis. This could help the reader and statisticians like me.
Going on, I also liked how the authors left out data for a validation sample. In many exploratory based investigations, this is not done. Fortunately, the authors were able to collect a large among of data points from a quite a few clinics in order to do this, and this is why collecting a sufficient data sample size can always be a big plus. In short, the investigator should always collect as much data points as possible for the investigation - regardless of what the power sample sizes might tell you. More is always better if possible.
Overall, great layout and study design for this investigation. I really don’t have too much to suggest. I always try to assemble in my mind the best study designs and layouts of various papers in order to bring everything together, and this is definitely a paper I hope to reference in the future.
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