Variation in classification of live birth with newborn period death versus fetal death at the local level may impact reported infant mortality rate

Table 2 Impact on reported statewide infant mortality rate for 1995–2000 if all hospitals classified events similarly according to each of four groups on percentage of events classified as fetal deaths

Hospital group (N)^A	Group definition	Events (%) within group classified as fetal death	Total events (%) in group	Infant nortality if all classified similarly to group^B
1 (8)*	≥75% of outcomes classified as fetal deaths	77.8%	1544 (19.2)	7.50
2 (15)^†	61 -- 74.9% of outcomes classified as fetal deaths	69.9%	3589 (44.6)	8.48
3 (4)^‡	55 – 60.9% of outcomes classified as fetal deaths	59.8%	1049 (13.0)	9.73
4 (4)^║	<55% of outcomes classified as fetal deaths	52.4%	1862 (23.1)	10.64
Total	--	66.0%	8044	8.95^C

^ANumber of the 31 hospitals selected for individual analysis based on ≥ 60 fetal death/early neonatal death events during the study period.
*This group also included events from hospitals with low birth numbers in counties with one of the 31 hospitals. This group contained the two hospitals with odds ratios that were statistically lower than the reference group.
^†This group also included the reference group of hospitals in counties with < 1% of statewide births during the study period as well as the 140 deliveries that occurred outside of hospitals. All 15 hospitals in this group had 95% C.I.s of adjusted odds ratios that contained 1.0.
^‡Three of these four hospitals had adjusted odds ratios ≥1.40, one of which was statistically higher than the reference group.
^║Three of these four hospitals had adjusted OR >2.0 that were statistically higher than the reference group. These three were affiliated with different academic medical centers.
^BInfant deaths per 1000 live births. Live birth denominator was adjusted for reclassification of fetal deaths as live births or live births as fetal deaths, as indicated. Total number of infant deaths reported in North Carolina from 1995–2000 was 5815. The adjusted number of infant deaths for the calculations of groups 1 through 4 was 4868, 5503, 6316, and 6911, respectively.
^CActual reported infant mortality rate for North Carolina, based on total reported infant deaths and live births for the six-year period.

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