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Correspondence |

Using the Proper Analytical Tools When Evaluating the Role of Midodrine in Resolving Septic Shock FREE TO VIEW

Ala-Eddin S. Sagar, MD; Praveen Vijhani, MD
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FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

Division of Pulmonary, Critical Care and Sleep Medicine, Internal Medicine, University of Texas Health Science Center at Houston (Ringgold Standard Institution), Houston, TX

CORRESPONDENCE TO: Ala-Eddin S. Sagar, MD, Division of Pulmonary, Critical Care and Sleep Medicine, Internal Medicine, University of Texas Health Science Center at Houston (Ringgold Standard Institution), 6431 Fannin St, MSB 1.434, Houston, TX 77030


Copyright 2016, . All Rights Reserved.


Chest. 2016;150(4):982-983. doi:10.1016/j.chest.2016.07.039
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We read with great interest the study by Whitson et al in CHEST (June 2016), examining the feasibility, utility, and safety of midodrine during the recovery phase from septic shock. In the study, the authors conclude that midodrine may reduce the duration of intravenously administered vasopressors, and may be associated with a reduction of ICU length of stay. While we understand the limitations of a retrospective study in avoiding any confounders, we cannot help but question the statistical tools used to compare both groups.

The mean rather than the median was used to analyze both ICU and hospital length of stay, concluding that ICU length of stay was shorter for the group using midodrine. The mean was also used when comparing the Acute Physiology and Chronic Health Evaluation (APACHE) IV scores between both groups. One can argue that using the median would have given a more relevant comparison. The median is less prone to be affected by skewed data and outliers, which would be anticipated in such retrospective studies. Weissman retrospectively analyzed the length-of-stay pattern of 4,499 patients in the ICU and demonstrated that when analyzing length-of-stay data, the median is more useful in comparing intergroup differences, and is the most useful measure of central tendency. Marik and Hedman made a similar observation, noting that length of stay is highly skewed toward longer stays because of the many outliers. This would imply that a single patient with a prolonged ICU stay, out of proportion compared with the rest of the patients, would significantly shift the mean and alter the statistical significance. The same argument can be made regarding a comparison of APACHE IV scores between both groups. It would be interesting to determine whether the statistical significance—or the lack of statistical significance in the case of APACHE IV scores—would hold if the median was used instead.

It was also interesting to know that 18 patients were discharged while receiving midodrine. As our experience with the use of midodrine in septic shock is limited, we wonder whether it is safe to discharge patients with a reversible cause of vasodilation, that is, septic shock, while receiving oral vasopressors, and the kind of follow-up required to wean them off.

We do agree with the authors that this is an exciting area for future research, with the potential to change our approach to managing patients with septic shock, and to expedite ICU turnover without compromising patient care.

References

Whitson M.R. .Mo E. .Nabi T. .et al Feasibility, utility, and safety of midodrine during recovery phase from septic shock. Chest. 2016;149:1380-1383 [PubMed]journal. [CrossRef] [PubMed]
 
Weissman C. . Analyzing intensive care unit length of stay data: problems and possible solutions. Crit Care Med. 1997;25:1594-1600 [PubMed]journal. [CrossRef] [PubMed]
 
Marik P.E. .Hedman L. . What’s in a day? Determining intensive care unit length of stay. Crit Care Med. 2000;28:2090-2093 [PubMed]journal. [CrossRef] [PubMed]
 

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References

Whitson M.R. .Mo E. .Nabi T. .et al Feasibility, utility, and safety of midodrine during recovery phase from septic shock. Chest. 2016;149:1380-1383 [PubMed]journal. [CrossRef] [PubMed]
 
Weissman C. . Analyzing intensive care unit length of stay data: problems and possible solutions. Crit Care Med. 1997;25:1594-1600 [PubMed]journal. [CrossRef] [PubMed]
 
Marik P.E. .Hedman L. . What’s in a day? Determining intensive care unit length of stay. Crit Care Med. 2000;28:2090-2093 [PubMed]journal. [CrossRef] [PubMed]
 
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