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K.K. Jatla, R.W. Enzenauer; The Application of Statistical Process Control (SPC) to Phacoemulsification (Phaco) Cataract Surgery . Invest. Ophthalmol. Vis. Sci. 2003;44(13):213.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Statistical process control (SPC) techniques were originally used for evaluating quality in manufacturing. The SPC chart consists of data plotted in a time sequence with the mean and upper and lower control limits (approximates +/- 3 standard deviations), graphically showing trends in the data. SPC analysis has been used previously to evaluate outcomes in cardiac surgery. We employed statistical process control charts to analyze cataract surgical parameters of "high volume" and "low volume" cataract surgeons at our institution. Methods: For the period between 3-1-02 through 9-1-02, we evaluated 180 cataract surgeries from 6 different surgeons (30 surgeries from each surgeon). A surgeon was considered "high volume" if he performed more than 6-8 cataracts per week. A surgeon was labeled "low volume" if less than 3-5 cataracts were performed per week. There were 3 high volume surgeons and 3 low volume surgeons in this study. Surgical parameters that were collected for all the surgeries included surgery time, phacoemulsification time and phacoemulsification power. SPC charts were used to compare the differences in surgery time, phaco time and phaco power between "high volume" and "low volume" surgeons using the QI AnalystR software package. Results: Our results showed that there was not a statistically significant difference between mean phaco time (P= 0.814) and phaco power (P=0.115) of low volume and high volume cataract surgeons. SPC charts displaying these variables showed normal statistical fluctuation with a limited number of outliers. Interestingly, the high volume surgeons’ phaco time and phaco power had higher upper control limits (UCL) than low volume surgeons’ surgical parameters. Surgical time of performing a cataract surgery was found to be statistically significantly lower (P<0.0001) for high volume surgeons. SPC chart analysis for surgical time also showed a smaller variation with fewer outliers for the high volume surgeons. Conclusions: Operative parameters such as phaco time and phaco power seem to be independent of surgical volume and may be described by standard models of statistical fluctuation. However, surgical time seems to be lower with a higher volume of cases. Lower surgical time may directly affect post-operative complications, surgical outcome, as well as cost. Statistical process control may be a valuable method to analyze variability in many ophthalmologic procedures, with the goal of minimizing variability to achieve better outcomes. Further studies are warranted to determine whether lower surgical time directly affect surgical outcome, post-operative complications, or cost.
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