Keywords
near-miss morbidity - maternal mortality - scoring system
Little progress has been made in the effort to lower the rate of maternal mortality
in the United States over several decades.[1] Indeed, recent data suggest that this rate may actually be rising.[2] This lack of progress is further demonstrated by the inability to narrow the racial
disparities that exists between white, black, and Hispanic populations with regard
to maternal mortality.[1]
These data cumulatively serve to emphasize the need to improve perinatal care. However,
despite the unacceptable epidemiological trends of maternal mortality rate in the
United States, the absolute number of cases remains quite low and is infrequent at
any one institution. Because the number of women who die as a result of pregnancy
is so low, evaluation of maternal mortality cases as a tool to improve perinatal health
has a limited utility. It is difficult to discern patterns of care that need refinement
with such a small number of applicable cases. As maternal morbidity is orders of magnitude
more common than maternal mortality, expanding the focus of case review to include
maternal morbidity would provide a larger population of interest.[3] The broadening of the focus to maternal morbidity has the potential to give insight
into methods to reduce maternal mortality, lessen racial disparities in adverse obstetric
outcomes, and identify preventable factors that lead to poor maternal outcome. Before
morbidity can be effectively studied, however, a standard metric needs to be developed.
The metric must identify women with morbidity that is significant enough to warrant
study and be plausibly related to maternal mortality.
In 2004¸ Geller et al devised a scoring system that identified significant morbidity.
After conceptualizing morbidity as a continuum (i.e., from minor to severe), these
investigators defined “near-miss” morbidity as the most severe morbidity that occurs
prior to, but does not result in, death.[4] In this framework, “near-miss” does not refer to a woman who nearly misses having
a morbid event, but who nearly misses a mortal event. Geller's system uses multiple
well-defined variables to identify women with near-miss morbidity and differentiates
them from other women with morbidity that is not as severe. This system can then be
used to identify women from perinatal databases without having to rely on individual
chart review and abstraction. Although Geller et al demonstrated a reasonable sensitivity
and specificity for their scoring system, this system has not been evaluated in settings
other than the originally studied institution, and its generalizability remains uncertain.
The objective of our study was to further assess and validate the Geller scoring system
for the identification of near-miss maternal morbidity.
Materials and Methods
This was a retrospective cohort study of women who delivered at a high-volume, urban,
tertiary care center over a 2-year period (2001 to 2002). This period of time was
chosen as it corresponded to the time during which patients for the Geller et al study
were also selected. Similarly, other methods for identification of patients were identical
to those described by Geller et al.[4] After receiving institutional review board approval, women with a high potential
for obstetric morbidity were identified using a perinatal and billing database that
included clinical information with searchable diagnoses and all deliveries that occurred
over the selected 2-year time period at the institution of interest. Identification
was based on the presence of comorbidities, adverse outcomes, or particular procedures.
A detailed list of parameters that were used to identify cases is outlined in [Table 1]. The medical records of these parturients were obtained, and a narrative summary
of their hospital course was prepared by a single trained research assistant. This
summary was then reviewed by three physicians. Each physician, based on his or her
impression of the patient's overall clinical course, assigned the case a given degree
of morbidity: none, minor, severe, or near-miss. The final morbidity designation was
based on the consensus opinion of the three physicians; when the three physicians
did not agree on the degree of morbidity, the final level of morbidity was assigned
by majority rule. For example, if two of the reviewers coded a given case as near-miss
morbidity and one of the reviewers coded that same case as severe morbidity, then
the case was identified for final analyses as near-miss morbidity. Because no gold
standard exists to assign the presence or the degree of maternal morbidity, the final
physician-derived designation was considered the gold standard to which the Geller
score was compared.
Table 1
Obstetric Parameters Used for Identification of Cases[4]
|
Diseases/Conditions
|
Morbid Events
|
Procedures/Interventions
|
|
Severe preeclampsia/eclampsia
|
Hemorrhage >1500 mL
|
Transfusion
|
|
Embolism
|
Wound dehiscence
|
ICU admission
|
|
Infection
|
Organ system failure
|
Extended Intubation
|
|
Ectopic/molar pregnancy
|
Abnormal vital signs/laboratories
|
Surgical Intervention
|
|
Cardiac disease
|
Abruptio
|
Return to the operating room
|
|
Cerebral vascular accident
|
Seizures
|
Readmission to the hospital
|
|
Accreta/increta/percreta
|
Stroke
|
Multiple medical interventions
|
|
ITP/TTP
|
Pulmonary edema
|
Hysterectomy
|
|
DIC
|
Prolonged hospital stay
|
|
ARDS
|
|
ARDS, acute respiratory distress syndrome; DIC, disseminated intravascular coagulopathy;
ICU, intensive care unit; ITP, idiopathic thrombocytopenic purpura; TTP, thrombotic
thrombocytopenic purpura.
All cases were then scored utilizing the weighted five-factor scoring system developed
by Geller et al ([Table 2]).[4] In this system, each case was assigned a total score based on the presence or absence
of the five factors. Each chart was abstracted for the occurrence of the relevant
events. When a given factor was present, the case was given the appropriate number
of points, and a total score was then obtained by summing all of the accorded points.
Any woman who received a score of greater than or equal to 8 was identified as having
had near-miss morbidity. Sensitivity, specificity, as well as positive and negative
predictive values for the identification of near-miss morbidity were calculated for
a Geller score of 8 or greater and for each component contributing to the score.
Table 2
Components of the Scoring System Proposed by Geller et al[4]
|
Points
|
|
Organ system failure (≥1 system)[a]
|
5
|
|
ICU admission
|
4
|
|
Transfusion >3 U PRBC
|
3
|
|
Intubation >12 h
|
2
|
|
Unanticipated surgical intervention
|
1
|
ICU, intensive care unit; PRBC, packed red blood cells.
a Central nervous system (coma, intracranial hemorrhage, blindness); cardiovascular
(cardiac arrest or parenteral treatment of hypotension); pulmonary (acute respiratory
distress syndrome, respiratory arrest); hematologic (disseminated intravascular coagulation,
platelets <50,000/mL); renal (creatinine >2.0 mg/dL, dialysis); gastrointestinal (liver
failure, colostomy).
Results
During the period of study, 17,275 women delivered at Northwestern Memorial Hospital.
Eight hundred fifteen cases were identified from the initial database search as being
at high risk for obstetric morbidity. There were no maternal deaths. Each rater's
determination with regard to frequency of the different levels of morbidity among
this cohort is presented in [Table 3]. The final physician designation, based on review of the overall narrative, determined
that 130 (15.9%) women had severe morbidity and 37 (4.5%) women had near-miss morbidity.
Thus, the overall prevalence of near-miss morbidity is estimated to be 0.2% (37/17,275).
Concordance of opinion among the three raters in determining whether a woman had near-miss
morbidity was high, with agreement in 93% of cases. The frequency of near-miss morbidity
among the selected population was similar to that reported by Geller et al in their
population (6.5%).[4]
Table 3
Morbidity Based on Narrative Review Stratified by Rater (n = 816)
|
Rater 1
|
Rater 2
|
Rater 3
|
|
No or minor morbidity
|
74.6
|
83.6
|
77.8
|
|
Severe morbidity
|
19.7
|
10.9
|
18.8
|
|
Near-miss morbidity
|
5.6
|
5.5
|
3.4
|
All data presented as percents.
With regard to the components present in the Geller et al scoring system,[4] 13.5% of women had an unanticipated surgical intervention, 3.4% had an extended
intubation, 4.4% had a transfusion greater than 3 U, 7.6% were admitted to the intensive
care unit (ICU), and 4.2% had at least one organ system fail. These events translated
into a scoring distribution as follows: 89.7% of women had scores from 0 to 2, 6.1%
had scores from 3 to7, and 4.2% had scores of at least 8. This last group of women,
therefore, was predicted by the scoring system to have had experienced near-miss morbidity.
Of these 34 women identified by the Geller scoring system as having near-miss morbidity,
30 (88.2%) actually had experienced near-miss morbidity as determined by the “gold
standard” of the full narrative. Conversely, seven women who had near-miss morbidity
were not identified using the scoring system. Thus, the scoring system had a sensitivity
of 81.1% (95% confidence interval [CI] 64.8 to 92.0%) and a specificity of 99.5% (95%
CI 98.7 to 99.9%) for the identification of near-miss morbidity. Positive and negative
predictive values were 88.2% and 99.1%, respectively. [Table 4] demonstrates the sensitivity and specificity of each individual component in the
Geller et al scoring system for identifying near-miss morbidity. The sensitivity and
specificity of the five-factor scoring system were significantly greater than provided
by each of the components independently.
Table 4
Sensitivity and Specificity of Individual Events for Identifying Near-Miss Morbidity
|
Sensitivity
|
Specificity
|
|
Organ system failure
|
42.1
|
97.7
|
|
ICU admission
|
78.9
|
95.9
|
|
Transfusion >3 U PRBC
|
63.2
|
98.8
|
|
Intubation >12 h
|
42.1
|
97.7
|
|
Unanticipated surgical intervention
|
73.7
|
89.5
|
ICU, intensive care unit; PRBC, packed red blood cells.
Discussion
In this study, we have demonstrated that the scoring system proposed by Geller et
al to identify women who have experienced near-miss morbidity retains its high sensitivity
and specificity when used in a population other than the one in which it was initially
developed.[4] The values for sensitivity and specificity (81.1% and 99.5%) that we obtained were
similar to those (100% and 93.9%) obtained in their analysis. Other aspects of the
results, such as the distribution of different types of morbidity and the fact that
the test characteristics were better for the five-factor scoring system than for any
individual contributing factor, were also similar between studies. This analysis gives
further support to the validity of the scoring system as a method by which women can
easily be identified as having had very significant, or “near-miss,” morbidity.
There is a great need to determine a uniform measure of significant maternal morbidity.
This need is underscored by the rising maternal death rate in the United States as
a whole. Yet, maternal death, although clearly important to track on a national level,
occurs so uncommonly that it cannot be used in an individual institution for quality
of care surveillance. Similarly, because a death is so uncommon, it is difficult to
use to discern care processes and systems that are associated with recurrent adverse
outcomes. Other individual outcomes may be used to indicate marked maternal morbidity.
However, there is no uniform agreement about which is best to use, and each has its
own potential limitations. For example, although ICU admission is often used as a
marker of significant morbidity, the variability among institutions regarding criteria
for ICU admission may limit its use as a useful comparator.[5]
[6] Furthermore, as our study reveals, individual events, such as ICU admission or extended
intubation, are not as useful as a multiple-factor scoring system in identifying which
women actually experienced the greatest morbidity, as judged by clinicians based on
a full care narrative.
The scoring system proposed by Geller et al, and externally validated in this study,
offers several potential advantages.[4] First, it provides a uniform approach to the identification of women with obstetric
morbidity that could be used by different institutions as a common metric to compare
outcomes. Second, it identifies an outcome that is significant, but still frequent
enough, that individual institutions can explore patterns of care and risk factors
that may be associated with the adverse outcome. Third, the scoring system can be
used to identify cases from perinatal or administrative databases minimizing the need
for full institutionwide chart review.
Limitations of the study also should be noted. This study was performed at a single
center, and accordingly the results may not be replicable at other institutions. Although
our center was different in multiple aspects from the one in which the scoring system
was originally generated, both are urban tertiary care centers with residency programs,
and the ability of the scoring system to work equally as well in rural, community,
or nonteaching hospitals is not certain.
Nevertheless, this study has replicated the findings of Geller et al[4] and has shown that the scoring system can be used to identify “near-miss” maternal
morbidity. Further evaluation may reveal its applicability at additional institutions,
as well as its ability to serve as a useful indicator of maternal outcomes and obstetric
care.
