THE MAGNITUDE OF
THE PROBLEM OF MATERNAL MORTALITY
Dear Editor,
In the March
issue of the Journal, Horon1 suggests the possibility that not
all maternal deaths were identified in her study “even by using additional
data sources”. Accordingly, the adjusted maternal mortality ratio in
Maryland for the years 1993 through 2000 of 22.2 per 100 000 live births
—which is 60.9% higher than the ratio based only on information reported in
death records— may still underestimate the true figure.
It is, in fact,
possible to estimate the magnitude of this ‘residual under-registration’ by
directly fitting Horon’s data into a log-linear capture-recapture model,2
an epidemiological tool for estimating or adjusting for the extent of
incomplete ascertainment using information from overlapping lists of cases
from distinct sources.3
According to the
results of this analysis, obtained with the help of EpiDat ® —a software in
the public domain4 (Table 1), an additional 12 maternal deaths
may have been expected, raising the total to 141 (95% confidence interval
132 to 152) maternal deaths between 1993 and 2000. Therefore, the magnitude
of the problem may well be closer to 24.3 per 100 000 [95%CI: 22.7 to 26.2]
in Maryland. If maternal deaths are assumed to be underreported at the same
level nationally as they are in Maryland, under similar source dependency
assumptions the maternal mortality ratio for the United States for 2001
would have been 17.4 per 100 000 live births.
Dr. Horon’s study
succeeds in providing strong evidence for the critical need of improving
data collection procedures and analysis to better understand this worldwide
devastating problem as well as to monitor progress towards its control.
Oscar J Mujica, MD MPH PHE
Acknowledgment
The author would
like to thank Cesar B. Vieira MD MPH MPHI, for his comments on a draft of
this letter.
References
1. Horon IL.
Underreporting of Maternal Deaths on Death Certificates and the Magnitude of
the Problem of Maternal Mortality. Am J Public Health
2005;95(3):478-82.
2. Chao A, Tsay
PK, Lin SH, Shau WY, Chao DY. The applications of capture-recapture models
to epidemiological data. Statistics in Medicine 2001;20:3123-57.
3. Hook EB,
Regal RR. Capture-recapture methods in epidemiology: methods and
limitations. Epidemiol Rev 1995;17(2):243-64. [errata: Am J
Epidemiol 1998;148(12):1219.]
4. EpiDat: programa para análisis epidemiológico de datos tabulados,
versión 3.0 [EpiDat: software for epidemiological analysis of tabulated
data, version 3.0]. Consellería de Sanidade de la Xunta de Galicia y
Organización Panamericana de la Salud.
Santiago de
Compostela & Washington DC; 2003 (downloadable at:
http://dxsp.sergas.es)