In Reply The inverse relationship found in our study between protein delivery and muscle wasting was hypothesis generating. Both Dr Heyland and colleagues and Mr Day were concerned that ICU length of stay may have been a confounding variable.
We prespecified an ICU length of stay of greater than 7 days as one of the inclusion criteria, with the primary end point (muscle loss) measured at day 10. Only 7 patients had an ICU length of stay between 7 and 10 days. The areas under the curve for cumulative organ failures over 7 days and 10 days were highly correlated (Figure). Therefore, we were justified in our use of area under the curve over this time frame.
Puthucheary ZA, McPhail MJW, Hart N. Acute Muscle Wasting Among Critically Ill Patients—Reply. JAMA. 2014;311(6):622–623. doi:10.1001/jama.2013.285426