I would be grateful for your advice on our forthcoming change-over from the Centaur TnI to the Centaur Ultra TnI assay. Our cut-offs for C-TnI have been <0.15 OK, O.15-0.3 as indeterminate with active follow up suggested, and >0.3 consistent with myocardial injury. (This data obtained from many years of results and follow up). We expect the new Ultra-TnI assay to have one cut-off of <0.04 OK and >0.04 requiring active management. (99% is 0.04 & FS is 0.03) But the company seems uncomfortable with any formal recommendations, and there seems to be a dearth of publications in this area. We on the other hand now have little access to our patient's complete clinical details to do our own comparative study. Although we are performing a within house comparison. We expect that our low end cut-off for C-TnI of 0.15 to be equivalent to 0.04 for the Ultra-TnI. Are our expectations set too high? What do you think? and what do you recommend?
Fred S. Apple, Ph.D
Changing troponin assays even within the same manufacturer can be stressful to both the lab and to clinicians. I favor using the 99th percentile cutoff IF the reference cutoff has been appropriately established with an appropriate mix of men and women and across different ethnic groups (see CLSI guideline C28-A2). I would ask the manufacturer for the data they used to establish their cutoff and request any published data in the literature that substantiates their claims. As an example of how different cutoffs are observed for the same assay (Abbott Architect), we found in an N = 2000 normal heparin plamsa samples a 99th percentile of 0.024 ng/mL compared to the FDA cleared package insert 99th percentile value of 0.012 ng/mL based on an N = 224. Cardiology, emergency medicine and laboratory medicine guidelines and recommendations are all in favor of moving towards this lower cutoff. Good luck.
Dr. Apple, You have been so successful in the profession that I am surprised at your response regarding keeping work out of home life. One of the challenges I face as a junior faculty member is the feeling that saying "no" to opportunities is detrimental to my advancement. I am constantly trying to juggle so many tasks that I inevitably take work home with me. Striking an appropriate balance is truly one of the biggest challenges I face. In all phases of your career have you truly been able to leave work at work?
Fred S. Apple, Ph.D
I must confess that before there were my wife and 2 kids that work did follow me home. However, today with a 10 yo around, the other is off to college, I find myself completing most activities before I leave the hospital at the end of the day. On the days that things pile up, I do bring one task home that causes my neighbors who dont sleep at night to ask me in the morning when im walking the dog, "why my study light was on till 1 AM" (while everyone else in my house sleeps soundly). Finding the right balance is very important, and hopefully will not force you to say no to opportunities that will help your growth.