Comparison of the obstetric anesthesia activity index with total delivery numbers as a single denominator of workload demand in Israeli maternity units

Abstract

Background: Obstetric anesthesia workload demand in Israel has increased due to both an increase in the requests for labor analgesia and a marked increase in the cesarean delivery rate. We propose a new workload-driven performance indicator, the Obstetric Anesthesia Activity Index (OAAI), to serve as a single denominator of obstetric anesthesia activity to enable direct comparison of different hospitals despite dissimilar rates of epidural labor analgesia and cesarean delivery.

Methods: We performed a secondary analysis of two recent national surveys by the Israel Association of Obstetric Anesthesia. In 2005 and 2007 questionnaires were sent to all Israeli hospitals requesting information on the total numbers of deliveries, epidurals, and cesareans annually, together with the anesthesia workforce allocated for the provision of obstetric anesthesia services. The OAAI was calculated based on the premise that epidurals and cesareans are the predominant determinants of obstetric anesthesia workload and that a typical epidural takes about half the time of a typical cesarean. Accordingly, the OAAI for each hospital was calculated as ((0.75 * number of epidurals per year) + (1.5 * number of cesareans per year))/365.

Results: This secondary analysis assessed the 25 maternity units in Israel that participated in both the 2005 and 2007 surveys. As expected, there was a wide inter-hospital variability in epidural and cesarean rates. Hospital rankings based on annual delivery numbers were different from those based on the OAAI. The OAAI correlated closely both with the number of epidurals (2005: Pearson 0.97, p < 0.0001; 2007: Pearson 0.97, p < 0.0001) and cesareans (2005: Pearson 0.94, p < 0.0001; 2007: Pearson 0.92, p < 0.0001). These correlations were better for the OAAI than for the annual delivery numbers.

Conclusions: As there was such a wide range of demand for different obstetric anesthesia services among different hospitals, the total number of deliveries is a poor summary indicator of obstetric anesthesia workload. The calculated OAAI better reflected the obstetric anesthesia workload as a single denominator of activity.

Figure 1

The wide variation in epidural and cesarean delivery rates in Israeli hospitals makes annual delivery numbers a poor assessment of obstetric anesthesia activity. For each composite figure, the upper portion consists of annual numbers of deliveries, epidurals, and cesareans. The lower portion represents the calculated OAAI. Ranking of hospital activity by annual delivery numbers alone does not reflect the ranking by OAAI. Data for 2005 (upper) and 2007 (lower).

Figure 2

The wide variation in epidural and cesarean delivery rates in Israeli hospitals is reflected in the contributions of epidural analgesia and cesarean anesthesia to the total OAAI in individual hospitals. Data for 2005 (left) and 2007 (right).

Figure 3

Correlation of annual epidural and cesarean numbers with annual delivery numbers (A, C) and with OAAI (B, D). Data for 2005 (A, B) and 2007 (C, D). The OAAI correlated more closely with both the number of cesarean deliveries and the number of epidurals. Although coupling exists as the OAAI is derived from both cesarean delivery and epidural rates, it is precisely for this reason that a single denominator is a more useful measure of obstetric anesthesia activity than annual delivery numbers.

Figure 4

The OAAI for individual hospitals according to obstetric anesthesia workforce allocation (data for 2005 only; 2007 survey did not collect workforce data).