Vol.3, No.7, 444-446 (2011) Health
doi:10.4236/health.2011.37073
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/HEALTH/
Assignment of ethnicity in patients with acute ischemic
stroke in northern israel
Gregory Telman1*, Efim Kouperberg2, Moshe Herskovitz2, Tarek Diab2, Hilel Hurani2, Elliot Sprecher2
1Department of Neurology, Rambam Medical Center, Haifa, Israel; *Correspongding Author:
2Department of Neurology, Technion Faculty of Medicine, Rambam Health Care Campus, Haifa, Israel.
Received 23 January 2010; revised 1 February 2010; accepted 11 March 2010.
ABSTRACT
The description of various methods for ethnicity
classification can be found in the literature,
though their reliability still remains unclear. We
examined inter-observer agreement in defining
the ethnic identification of patients in a bi-ethnic
population (Arab-Jewish) in northern Israel,
using place of birth and residence in addition to
given and family names. Data about 1006 con-
secutive patients with acute ischemic stroke
were gathered from our stroke registry. The data
were analyzed by four independent observers
(authors MH, TD, HH, GT) aiming to assign pa-
tients either as Arabs or Jews. Agreement be-
tween all four observers was excellent, as as-
sessed by Fleiss’ Kappa statistic (κ = 0.96). We
conclude that the use of given and family names
of patients, together with their place of birth and
residence, achieved near-perfect inter-observer
agreement and a highly reliable assignment of
ethnicity in two large ethnic population groups –
Arabs and Jews – in northern Israel.
Keywords: Stroke; Ethnicity
1. INTRODUCTION
Ethnic differences in the etiology, clinical picture,
work-up, and outcome of numerous diseases are well
established [1-9]. This problem seems to be attracting
growing interest. One of the important issues in studying
ethnic influence is the correct assignment of the ethnic
identity of patients involved in any given study. Ob-
viously, precise ethnic identification is required for ob-
taining reliable results. The description of various me-
thods for ethnicity classification can be found in the li-
terature, though their reliability still remains unclear
[10-15]. Therefore, we conducted an inter-observer
agreement study on the ethnic assignment of patients in
a bi-ethnic population (Arab-Jewish) in northern Israel,
using place of birth and residence in addition to given
and family names. The results of this study are highly
important for planning of future studies devoted to the
influence of ethnicity on different aspects of cerebro-
vascular diseas es in our region.
2. MATERIALS AND METHODS
Data were gathered from our stroke registry on 1006
consecutive patients with acute stroke who had been
hospitalized once in the Department of Neurology in a
major hospital in northern Israel (Rambam Health Care
Campus) during the period from 2001 to 2003. For the
ease of processing and the prevention of double-counts,
25 additional patients who had two or more hospitaliza-
tions during this period were not included in the study.
The data presented for analysis included the patients’
given and family names together with their place of birth
and residence at the time of the event.
Four independent observers, all of whom are medical
doctors, were invited to participate in th e analysis and to
define an ethnic assignment of patients as Arab or Jew-
ish. The observers included an Israeli-born Jew (M.H),
two Israeli-born Arabs (T.D and H.H), and one immi-
grant from the former Soviet Union living in Israel since
1992 (G.T). All of the observers received a table of data
prepared by an additional person (E.K), who was not
serving as an observer. The table included four items:
first and family names together with place of birth and
residence at the time of the index event. The observers
were required to assign each patient as an Arab or a Jew.
After the assignments were completed by all four ob-
servers, the statistical analysis was conducted. Since four
observers were employed, Fleiss’ Kappa agreement sta-
tistic was used instead of the conventional two-observer
Kappa.
3. RESULTS
Results of estimation of ethnicity by every observer
are presented in Ta b l e 1 . Note that complete agreement

G. Te lman et al. / Health 3 (2011) 444-446
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445
Table 1. Distribution of agreement on ethnic assignment
across observers.
Observer A Observer B Observer C Observer D Number of
cases
J J J J 786
A A A A 195
J A J J 6
A A A J 4
J J J A 4
A A J A 3
A J J A 2
J J A J 2
A J A A 1
A J A J 1
J A A A 1
J A A J 1
J = Jewish et h nicity; A = Arab ethnicity.
across four observers was found in more than 97.5% of
the cases evaluated.
Fleiss’ Kappa was 0.96 across all four observers, in-
dicating near-perfect agreement in the assessment of
ethnicity.
4. DISCUSSION
The identification of patient ethnicity by names, with
or without additional factors such as place of birth, has
been widely used in medicine for many years [16-21].
There have also been numerous attempts to use compu-
terized systems for this aim as well [22-25]. However,
these methods achieve results of varying reliability when
applied in different ethnic populations [26-30].
We attempted to assign ethnicity in a bi-ethnic popu-
lation of Arabs and Jews in northern Israel. Both of these
large ethnic groups are ethnically heterogeneous. The
Jewish population includes two main groups: Ashkenazi
Jews from Central and Eastern Europe, and Sephardic
Jews from the Mediterranean and North Africa [31]. The
Arab population includes Sunni Muslims, Druze, and
Christian Arabs [32].
Despite being so ethnically heterogeneous, the first
names and surnames of both populations remain highly
distinctive between them. Two additional circumstances
are helpful in the assignment of ethnicity to Arabs and
Jews in the Israeli population. The first circumstance is
that a significant number of Jewish people immigrated to
Israel before and especially after the State of Israel was
established in 1948. Thus, those patients who were born
in countries other than Israel can safely be assigned to
the Jewish population. The second circumstance is that
there are numerous densely populated areas of Israeli
Arabs. As there is very little genetic intermingling be-
tween the two populations, a patient’s place of residence
in one of these areas is a clear indicator of Arab ethnicity.
In conclusion, when considering the patients’ given and
family names, together with their place of birth and res-
idence, we were able to achieve extremely good in-
ter-observer agreement, thereby allowing a highly relia-
ble assignment of ethnicity in the Arab-Jewish popula-
tion of northern Israel. The results of our study demon-
strate that even in case of retrospective studies, when
there is no possibility to define ethnicity by direct patient
interview, the method of ethnicity assignment by names
and place of birth could be highly reliable.
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