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Correspondence  |   October 2004
Intraservice Time Is Not a Proxy for Operating Room Time
Author Affiliations & Notes
  • Amr Abouleish, M.D., M.B.A.
  • ‡ University of Texas Medical Branch, Galveston, Texas.
Article Information
Correspondence
Correspondence   |   October 2004
Intraservice Time Is Not a Proxy for Operating Room Time
Anesthesiology 10 2004, Vol.101, 1041-1042. doi:
Anesthesiology 10 2004, Vol.101, 1041-1042. doi:
In Reply:—
We appreciate the insight provided by Drs. Hannenberg and Cohen into the process used by the Centers for Medicare and Medicaid System to develop the times assigned to each surgical Current Procedural Terminology. Access by Drs. Hannenberg and Cohen, who both have worked with the American Medical Association-Specialty Society Relative Value Update Committee as America Society of Anesthesiologists representatives, clarifies important limitations of our methodology. In our article, we compared Actual In-Room times to “National Average Times” obtained from the Centers for Medicare and Medicaid System database. Because the National Average Times included only skin-to-skin times, whereas we used total in-room times from the contributing institutions, our analysis would systematically overestimate the difference associated with longer surgical times, as suggested by Drs. Hannenberg and Cohen. Unfortunately, the materials provided on the Centers for Medicare and Medicaid System Web site with the data1do not specifically define the intraservice times as skin-to-skin.
The obvious question is, “By how much did this analysis overestimate the differences?” To answer this question, we reviewed data from Hospital A comparing case duration (as defined in the study as in-room time) with actual intraservice time (as defined as skin-to-skin time) and Centers for Medicare and Medicaid System National Average Time (also intraservice time). We found that the mean actual intraservice time (133 ± 114 min) represented approximately 91% of the mean actual in-room time (146 ± 117 min) and that the distributions of times were similar (table 1and fig. 1) Therefore, out systematic error would be approximately 13 min/case.
Table 1. Actual Intraservice Time, Actual In-room Time, and CMS Intraservice Time 
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Table 1. Actual Intraservice Time, Actual In-room Time, and CMS Intraservice Time 
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Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
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However, in our study, we set limits to the difference between the actual and average times of 180 and 60 min.1 As noted in the Discussion of the article, we did this initially to limit the issue of multiple procedures as described by Drs. Hannenberg and Cohen. However, we also believe that use of these limits would reduce the discrepancy due to our use of intraservice time versus  in-room time for the comparison. Using the 180-min limit, 8% of the cases (1,022 cases) had a duration that was 180 min greater than the National Average Time. With the 60-min limit, 37% of the cases (4,778 cases) had a duration that was 60 min greater than the National Average Time. Therefore, we believe that our cumulative error was less than the apparent 13 min/case.
Unfortunately, the Centers for Medicare and Medicaid System database is one of the only publicly available databases for durations by surgical Current Procedural Terminology. For example, Centers for Medicare and Medicaid System contracted to use a proprietary database to assess the validity of their intraservice times determined by survey information.2Therefore, the use of the Centers for Medicare and Medicaid System database has limitations, as we noted in our original discussion of our data. In contrast, the times per anesthesia procedure are actual times billed to Centers for Medicare and Medicaid System and are not based on surveys. These times can be used to evaluate anesthesia times but have limitations in comparing surgical procedures because multiple procedures may be performed even though only one anesthesia code is listed.2 
In summary, the purpose of our study was to demonstrate quantification of staffing costs associated with longer surgical durations. We believe that the more precise definition provided by Drs. Hannenberg and Cohen strengthens the value of that demonstration.
‡ University of Texas Medical Branch, Galveston, Texas.
References
Abouleish AE, Dexter F, Whitten CW, Zavaleta JR, Prough DS: Quantifying net staffing costs due to longer-than-average surgical case durations. Anesthesiology 2004; 100:403–12Abouleish, AE Dexter, F Whitten, CW Zavaleta, JR Prough, DS
Abouleish AE, Prough DS, Zornow MH, Hughes J, Whitten CW, Conlay LA, Abate JJ, Horn TE: The impact of longer-than-average anesthesia times on the billing of academic anesthesiology departments. Anesth Analg 2001; 93:1537–43Abouleish, AE Prough, DS Zornow, MH Hughes, J Whitten, CW Conlay, LA Abate, JJ Horn, TE
Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
Fig. 1. Distribution of cases by times. The Actual Intraservice and Actual In-Room have similar distributions, with 14–15% of cases with more than 4 h of duration in contrast to 4% of Centers for Medicare and Medicaid (CMS) Intraservice. Intraservice time is defined as “skin-to-skin” time. n = 12,765. 
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Table 1. Actual Intraservice Time, Actual In-room Time, and CMS Intraservice Time 
Image not available
Table 1. Actual Intraservice Time, Actual In-room Time, and CMS Intraservice Time 
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