129 / 264
is higher in younger (
<
9 years) than in older CWU patients.
12
Secondly, the ratio between residual and recurrent disease
might depend on follow-up length. Therefore, a 5-year follow-up
is essential to evaluate both types of disease recurrence.
7,13,14
Thirdly, distinction within the study between residual and
recurrent disease was important because of different key
aspects in etiology.
8
The aforementioned items for relevance
were appointed priority items (see Table I, marked with *). Pri-
ority items for validity were: “loss to follow-up”, “missing data”,
and “confounding by indication”. Both a high loss to follow-up
percentage and missing data could lead to biased outcomes. In
the third place, confounding by indication is important because
severe cholesteatoma cases tend to be treated by CWD rather
than CWU.
15
Subsequent to scoring each individual CAT item,
studies received an overall score for both relevance and validity:
low (L) (0–2.5 points), moderate (M) (3–5.5 points) or high (H)
( 6 points) (Table I). Articles received 1 point per item when a
plus (
1
) was scored and 0.5 point when a plus/minus (
6
) was
scored; priority items received double points. We selected stud-
ies with a moderate to high relevance for inclusion in the cur-
rent review.
Calculations and Statistics
We performed statistical pooling of data when there was
similarity between studies in: patients’ age groups, applied out-
come measures, type of applied statistical analysis and elected
follow-up moments. We used Review Manager (RevMan) 5.3
software to establish analysis (version 5.3. Copenhagen: The
Nordic Cochrane Centre, The Cochrane Collaboration, 2014).
We preserved meta-analysis results when the I
2
was between
0% and 40%.
16
We extracted original data from included studies
to calculate the absolute risk reduction (ARR) and relative risk
(RR). We used the Fisher’s exact test in SPSS 22 (IBM Corp.,
Armonk, NY) to calculate
P
values. We considered a value of
P
<
.05 significant.
RESULTS
Retrieving Studies
We retrieved a total of 2,060 articles, which were
all screened by evaluating the title and abstract. From
this process, 125 articles were selected for full-text
screening (Fig. 1). We considered seven articles eligible
to answer our research question (Fig. 1). Snowballing
revealed an eighth article
4
, a master’s thesis, which was
not indexed in selected databases (Fig. 1). Reverse snow-
balling revealed no additional articles.
Assessing Studies
The overall relevance was moderate in six studies
(Table I). One study
4
scored high and one study
17
scored
low on relevance. The overall validity of the retrieved
studies was graded low to moderate (Table I). Publica-
tion years of the articles ranged from 1979 to 2010. Two
studies included only adults in their studied cohort.
4,18
In addition, two studies only included acquired choles-
teatomas.
4,7
Seven studies did not report whether reop-
erations were included. Only one study
19
provided well-
described baseline characteristics. Three studies defined
the difference between residual and recurrent dis-
ease
4,15,18
(Table III). The follow-up duration was at
least 5 years in four studies.
6,17,19,20
In only three stud-
ies, all patients were operated on by the same sur-
geon.
7,15,18
In four studies
7,15,17,20
the overall validity
was moderate; whereas it was low in the remaining
studies.
4,6,18,19
Loss to follow-up was 20% or less in three
studies
15,17,20
and the method of handling of missing
data was reported in only one study.
15
In two studies,
6,19
the operation technique was described in a protocol. In
the study of Brown
6
, the elected surgical technique for
cholesteatoma removal was the intact canal wall tympa-
noplasty and mastoidectomy, as advocated by House and
Sheehy.
21
Only one of our included studies (Ajal-
loueyan
19
) applied an obliteration technique, published
previously by Quaranta et al.
22
In the remaining four
studies
7,15,17,20
, the operation protocols were not clearly
defined. The method of determining whether cholestea-
toma recidivism had developed, occurred according to a
well-defined protocol in two studies.
6,19
Seven articles
were biased by confounding by indication.
4,6,15,17–20
We
excluded one of the eight studies
17
with a low relevance:
report of adult residual disease only. Conclusions are
based on the remaining seven included studies with a
moderate to high relevance (Table I). The study reported
by Declerck
4
seemed to be the most relevant to answer
our research query because adult patients with an
acquired cholesteatoma were included. However, the
studies of Nyrop
7
and Stankovic
15
scored the highest
values on validity in our CAT (Table I). Therefore,
results from the latter two studies were suggested to
provide the most unbiased insight. There was a high
amount of statistical heterogeneity in the reported risk
differences (I
2
5
96%). We decided not to include Palmg-
ren’s study
20
in the heterogeneity analysis because
patient numbers could not be derived from recurrence
percentages. In addition, we defined whether heteroge-
neity was different for residual or recurrence numbers of
the six studies: 89% and 92%, respectively. We consid-
ered an I
2
below 40% to be acceptable; therefore, we
decided not to pool results.
Data Extraction
The extracted data are presented in Tables II and
III. The selected studies included 1,268 operated ears for
the CWU group and 1,038 ears for the CWD group
(Table II). The follow-up ranged between 6 months and
10 years. Two studies
4,18
reported results for patients
above 18 years and four studies reported results for
patients over 15 years.
6,7,15,19
The remaining study
20
mentioned the mean ages of the youngest 50 patients
and the oldest 50 patients (Table II). The data of the
study of Declerck
4
are displayed in separate rows
because one group was followed until the second-look
operation and the second had a longer follow-up (mean
follow-up: 2.5 years) (Table II). Six articles
4,6,7,18–20
reported a higher percentage of disease recidivism after
the CWU (range 15% to 61%) than after the CWD proce-
dure (0 to 13%) (Table II). Four of these differences were
statistically significant (Table II). Contrarily, Stankovic
15
reported disease recidivism of 8% after the CWU and
22% after the CWD technique (
P
<
.001). Both the abso-
lute risk reduction (ARR range
2
14% to 61%) and the
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108