CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 5, June 2012
282
AFRICA
Methods
MEDLINE, EMBASE and Google Scholar were searched
for English-language publications of observational studies of
ECP that were conducted from inception of the respective
database through to December 2009. Search terms included:
acute pericarditis, pericardial effusion, ECP, pericardial
tamponade, cardiac tamponade, tuberculous pericarditis, uraemic
pericarditis, purulent pericarditis, idiopathic pericarditis, viral
pericarditis and constrictive pericarditis. Limits included: the
English language, human beings and the following MeSH terms
(‘Case-Control Studies’[MeSH] OR ‘Cohort Studies’[MeSH]
OR ‘Epidemiologic Studies’[MeSH] OR ‘Cross-Sectional
Studies’[MeSH] OR ‘Retrospective Studies’[MeSH] OR
‘Prospective Studies’[MeSH]). In addition to searching the
databases, we contacted researchers in the field, and searched the
bibliographies of published reviews and studies on pericardial
disease for relevant studies.
The eligibility criteria for inclusion and exclusion from the
study, which are based on the Loney criteria for critical appraisal
of research articles on prevalence of disease, are shown in
Table 1.
11
To be included in the review, a study had to provide
sufficient information to enable determination of the proportion
of study participants diagnosed with ECP and at least six other
eligibility criteria.
Studies where malignancy was the predominant cause of
pericarditis were excluded from this systematic review because
patients with this diagnosis generally do not survive long
enough to develop constrictive pericarditis.
1,12
Studies of patients
with pericardial effusion that resulted from aortic dissection,
myocardial infarction, and trauma to the thorax were also
excluded because pericardial sequelae are uncommon among
long-term survivors of these conditions.
1,13-15
After the relevant studies were selected, individual patient
data were extracted and reviewed in order to exclude patients
with malignancy-associated ECP. Where relevant data could not
be extracted from the published manuscripts, we were able to
obtain the information on individual participants from the study
authors. We conducted a meta-analysis of the individual patient
data using the StatsDirect software (
. For
the meta-analysis, StatsDirect first transformed proportions into
a quantity (the Freeman-Tukey variant of the arcsine square root-
transformed proportion) suitable for the usual fixed and random-
effects summaries.
16,17
The pooled prevalence was calculated as
the back-transform of the weighted mean of the transformed
proportions, using inverse arcsine variance weights for the
fixed-effects model
16
and DerSimonian-Laird
17
weights for the
random-effects model.
We used the Cochran Q test to assess statistical heterogeneity
between studies and, in the absence of significant heterogeneity
(
p
>
0.1), combined the data using a fixed-effects method.
Otherwise, we used the random-effects method. In addition,
we used Higgins
I
2
statistic to quantify inconsistency across the
studies included in the meta-analysis. The test statistic describes
the percentage of the variability in effect it estimates that is due
to true heterogeneity rather than chance. The closer the
I
2
value
is to 100%, the more likely it is that true heterogeneity exists,
and therefore the less reliable the combined estimate becomes.
MN conducted the electronic searches and selected the
studies, all of which were reviewed by CW and BMM.
The reporting of the systematic review is in keeping with
standard recommendations for reporting systematic reviews of
observational studies.
18
Definitions
Effusive constrictive pericarditis was classified as definite or
probable, based on the methods used to establish the diagnosis.
2,9
Studies where the diagnosis was based on clinical assessment
alone were rejected.
Patients were classified as having definite ECP if the
diagnosis was based on intra-pericardial and intra-cardiac
haemodynamics, determined before and after pericardiocentesis.
This haemodynamic definition required that: (1) the
pre-pericardiocentesis transmural filling pressure (i.e. the
difference between the elevated intra-pericardial pressure and
the right atrial pressure) was less than 2 mmHg; (2) the
post-pericardiocentesis intra-pericardial pressure fell to near 0
mmHg; and (3) the post-pericardiocentesis right atrial pressure
failed to fall by 50% or to a level below 10 mmHg.
3
The diagnosis of ECP was considered probable if it was
established on the basis of echocardiography or magnetic
resonance imaging. There are no published prospectively derived
consensus diagnostic criteria for ECP using these imaging
modalities,
9
but widely accepted criteria include evidence of the
following criteria in a patient with a pericardial effusion: (1)
pericardial thickening; (2) abnormal or paradoxical movement of
the interventricular septum; (3) a plethoric dilated inferior vena
cava with reduced narrowing during inspiration; and (4) marked
respiratory variation of the mitral inflow Doppler pattern.
Finally, the diagnosis of ECP was rejected if it was established
without ancillary imaging or haemodynamic assessment, i.e. if
the diagnosis was made on clinical assessment alone.
Results
A flow chart for the selection process is provided in Fig. 1. Five
TABLE 1. ELIGIBILITY CRITERIA FOR STUDIES
OF THE SYSTEMATIC REVIEW
Inclusion criteria
1. The study design was observational (case control, cross sectional
and cohort); cross sectional studies were accepted for the determi-
nation of prevalence.
2. A definition of the syndrome of effusive constrictive pericarditis
was given.
3. The inclusion and exclusion criteria for the participants were
clearly stated.
4. There was a clear description of the number of participants in the
study.
5. The number or proportion of participants in the study with effu-
sive constrictive pericarditis was clearly stated.
6. The method of diagnosis of effusive constrictive pericarditis was
described and determined in an unbiased manner.
7. There was an adequate description of the study setting.
8. There was an adequate description of the study population.
Exclusion criteria
1. The number or proportion of participants with effusive constric-
tive pericarditis was not available.
2. The aetiology of pericarditis was a malignancy, myocardial infarc-
tion, aortic dissection, or trauma to the thorax.
3. The diagnosis of effusive constrictive pericarditis was based on
clinical assessment only.
