Interaction between serum chloride increase and baseline chloride level
Initial correspondence from Drs. Shen, Yan, and Cai
Recently, Dr. Barhight et al. reported an association between chloride increase and high mortality in critically ill children [ 1]. Although well designed, their study presents several limitations. First, the number of deaths in the cohort is small (4%, 71/1935). However, 21 variables were included in the logistic regression model (Table 2). Although no consensus has been reached, the rule of thumb is that at least 10 events per variable [ 2] are needed to avoid bias in multivariable regressions. Thus, the robustness of Barhight’s findings needs careful evaluation. Second, multicollinearity issues resulting from highly correlated predictors also play an important role in bias [ 2]. While the correlations in this study (for instance, the correlation between serum sodium and chloride) may be minimized by the fact that the continuous variables were translated into categorized variables, the result of a multicollinearity test...
Compliance with ethical standards
Conflicts of interest
All authors declare that they have no conflict of interest.
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