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Correspondence |

Considerations for the Interpretation of the Results Described in “Analysis of National Trends in Admissions for Pulmonary Embolism” FREE TO VIEW

Barret Rush, MD
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Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada

Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA

CORRESPONDENCE TO: Barret Rush, MD, Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Rm 2438, Jim Pattison Pavilion, 2nd Floor, 855 W 12th Ave, Vancouver, BC, V5Z 1M9, CANADA


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;150(2):467. doi:10.1016/j.chest.2016.03.064
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The recent publication by Smith et al in CHEST (July 2016) entitled “Analysis of National Trends in Admissions for Pulmonary Embolism” was a thought-provoking examination of national trends in the management of pulmonary embolism. There are, however, several significant issues that were not addressed by the authors that warrant explanation.

First, the Nationwide Inpatient Sample (NIS) underwent significant revisions between 1993 and 2012. The 1993 sample covered only 17 states and represented approximately 54% of the US population, whereas by 2012, the NIS captured patients from 44 states covering approximately 96% of the US population. The authors' use of US Census data to create the denominator for national rates of pulmonary embolism (PE) admissions during the study period may not be correct given the limited scope of earlier years of the NIS. Also, there was a complete redesign of the NIS sampling methods for the year 2012 that requires significant adjustments for trend analysis when comparing with previous years. The authors made no comment on adjustments for trend analyses accounting for changes in the NIS, including the major redesign for 2012. Also, it is assumed, but not stated, by the authors that proper complex survey procedures were used in the analysis of the data set.

Second, the authors' findings of decreased length of stay and mortality during the study period is in keeping with overall decreases in length of stay and mortality across all diagnoses in the NIS. These trends likely reflect changes in sampling methods of the NIS, including changes in hospital inclusion types (rehabilitation hospitals) and discharge estimation calculations. In addition, changes in International Classification of Diseases, ninth revision coding practices over a 20-year period could influence the results of the analysis and should be acknowledged as a limitation.

The authors should be commended for their important contribution to the field, and there is indeed a possibility of increased rates of hospitalization for PE due to increased diagnosis from CT angiography. However, the limitations of the NIS, especially across two major redesigns, must be taken into account for the results of this analysis to be interpreted.

References

Smith S.B. .Geske J.B. .Kathuria P. .et al Analysis of national trends in admissions for pulmonary embolism. Chest. 2016;150:35-45 [PubMed]journal. [CrossRef] [PubMed]
 
HCUP Healthcare Cost and utilization Project. HCUP Methods Series: Using the HCUP National Inpatient Sample to estimate trends, 2015.http://www.hcup-us.ahrq.gov/reports/methods/2006_05_NISTrendsReport_1988-2004.pdf. Accessed March 1, 2016.
 
HCUP Healthcare Cost and utilization Project. HCUP Methods Series: Nationwide Inpatient Sample Redesign Final Report, 2014.https://www.hcup-us.ahrq.gov/reports/methods/2014-04.pdf. Accessed March 1, 2016.
 

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References

Smith S.B. .Geske J.B. .Kathuria P. .et al Analysis of national trends in admissions for pulmonary embolism. Chest. 2016;150:35-45 [PubMed]journal. [CrossRef] [PubMed]
 
HCUP Healthcare Cost and utilization Project. HCUP Methods Series: Using the HCUP National Inpatient Sample to estimate trends, 2015.http://www.hcup-us.ahrq.gov/reports/methods/2006_05_NISTrendsReport_1988-2004.pdf. Accessed March 1, 2016.
 
HCUP Healthcare Cost and utilization Project. HCUP Methods Series: Nationwide Inpatient Sample Redesign Final Report, 2014.https://www.hcup-us.ahrq.gov/reports/methods/2014-04.pdf. Accessed March 1, 2016.
 
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