Cystic fibrosis mortality and survival in the UK: 1947-2003

Abstract

Data up to 1995 on the survival of 3-yr cohorts of patients with cystic fibrosis (CF) born in the UK in the period 1968-1992 have previously been published. The present study reports survival data up to the end of 2003 together with a 2003 population estimate. All subjects with CF born in the UK in the period 1968-1992 were identified up to 1997 by active enquiry through recognised CF clinics and other hospital consultants. Information from the death certification authorities up to the end of 2003 was added. Death certificates that could not be matched with UK Cystic Fibrosis Survey records were investigated and the data reconciled. The observed survival up to 2003 of CF patients born in 1978 was 55% for males and 49% for females. For 1988 and 1992 the data were 91 and 88%, and 97 and 96%, respectively. The estimated 2003 mid-year CF population was 8,284. The continuing improvement in survival of cystic fibrosis patients in successive cohorts means that the previous prediction of median survival of >50 yrs of age for individuals born in 2000 continues to look realistic, even in the absence of proven effective therapy aimed at correcting the basic cystic fibrosis defect.

Full text

Cystic fibrosis mortality and survival in the
UK: 1947–2003
J.A. Dodge*, P.A. Lewis
#
, M. Stanton
#
and J. Wilsher
#
ABSTRACT: Data up to 1995 on the survival of 3-yr cohorts of patients with cystic fibrosis (CF)
born in the UK in the period 1968–1992 have previously been published. The present study reports
survival data up to the end of 2003 together with a 2003 population estimate.
All subjects with CF born in the UK in the period 1968–1992 were identified up to 1997 by active
enquiry through recognised CF clinics and other hospital consultants. Information from the death
certification authorities up to the end of 2003 was added. Death certificates that could not be
matched with UK Cystic Fibrosis Survey records were investigated and the data reconciled.
The observed survival up to 2003 of CF patients born in 1978 was 55% for males and 49% for
females. For 1988 and 1992 the data were 91 and 88%, and 97 and 96%, respectively. The
estimated 2003 mid-year CF population was 8,284.
The continuing improvement in survival of cystic fibrosis patients in successive cohorts means
that the previous prediction of median survival of .50 yrs of age for individuals born in 2000
continues to look realistic, even in the absence of proven effective therapy aimed at correcting the
basic cystic fibrosis defect.
KEYWORDS: Cystic fibrosis, epidemiology, expectation of life, survival
S
tandard methods for the collection and
analysis of data on national mortality have
long been available from the World Health
Organization (WHO) [1]. There are two separate
parts to data collection. The first is the total
population census and the second is the recording
of deaths in that population. An electronic
literature search in July 2005 (using Science
Citation, Medline and Embase as databases and
cystic fibrosis (CF), mortality, survival and inci-
dence as search terms) showed four national
censuses of a CF population for the purpose of
calculating disease incidence. They were: one for
Sweden for the period 1950–1957 [2], one for the
Netherlands for 1961–1965 [3], one for the former
Czechoslovakia (now Czech Republic) for 1960–
1967 [4] and one for the UK for 1968–1993 [5–7].
The UK census data, which was collected by the
UK Cystic Fibrosis Survey (UKCFS) until 1997,
has been linked with subsequent national death
registration data, thus attempting to adhere to the
WHO criteria for mortality statistics. Death
certification data for children in England and
Wales showed a striking decline in post-neonatal
mortality from CF between 1968 and 2000 and
also a steady but less marked decline among 1–
5 yr olds [8]. The present report expands this
information to include adults and compares data
from successive cohorts.
The sources of the data have previously been
described in detail elsewhere [5]. Briefly, data
were initially obtained by regular surveys sent to
all paediatricians and chest physicians in the UK,
among others. Later, the number of respondents
was reduced by eliminating those who stated that
they did not look after CF patients, usually
naming colleagues who did. Clinicians who did
not respond by the due date were reminded,
usually by telephone calls, and each survey was
not concluded until the coordinator was satisfied
that all the data up to the end of an agreed
calendar year had been obtained. This meant that
published reports were irregular and not annual,
as originally hoped. The UKCFS is unique in its
coverage of the CF population, being clinician-
based and not clinic-based, and previous surveys
indicated that it included .95% of patients.
Although there is a wide variety of CF pheno-
types, which may to some extent modify clinical
presentation and apparent incidence in different
populations [9], the common approach to patient
management in many countries suggests that, in
the absence of other data, the UK mortality data
can be taken as illustrative of a general trend.
As a further report in the present authors’ series
based on UKCFS data, an updated cohort
survival data and current survival data for the
UK is presented in the current study, including,
AFFILIATIONS
*Dept of Child Health, University of
Wales Swansea, Swansea, and
#
Dept of Mathematical Sciences,
University of Bath, Bath, UK.
CORRESPONDENCE
J.A. Dodge
Dept of Child Health
University of Wales Swansea
Singleton Hospital
Sketty Road
Swansea SA2 8QA
UK
Fax: 44 1291671364
E-mail: j.a.dodge@btinternet.com
Received:
July 31 2006
Accepted after revision:
November 27 2006
SUPPORT STATEMENT
The active surveillance was
supported by a grant from the Cystic
Fibrosis Trust between 1983 and
1997. The death certification data
reported were purchased from the
relevant authorities in England,
Wales, Scotland and Northern Ireland
using funds from the University of
Bath (Bath, UK) and the University of
Wales Swansea (Swansea, UK). No
competing interests have been
declared. J.A. Dodge initiated the UK
Cystic Fibrosis Survey study and
followed up unmatched death
certificates. P.A. Lewis suggested the
present paper and calculated the
cohort survival. M. Stanton calculated
the current survival and expectation
of life. J. Wilsher handled the left-
truncated survival and the population
estimate and incidence. All authors
contributed to drafting the paper.
STATEMENT OF INTEREST
None declared.
European Respiratory Journal
Print ISSN 0903-1936
Online ISSN 1399-3003
522 VOLUME 29 NUMBER 3 EUROPEAN RESPIRATORY JOURNAL
Eur Respir J 2007; 29: 522–526
DOI: 10.1183/09031936.00099506
CopyrightßERS Journals Ltd 2007

for the first time, life tables with the (tentative) expectation of
life for people with CF.
METHODS
Data
Active surveillance of the CF population ran over the period
1982–1997 under the auspices of the (then) British Paediatric
Association and the British Thoracic Society, and was funded by
the Cystic Fibrosis Trust. The present study was essentially a
follow-up of a previous report elaborated in 1997 [6] using the
subset of the 1997 data utilised in previous mortality calcula-
tions. Personal identification data were removed before passing
it to the statisticians. It included all known individuals resident
in the UK with a diagnosis of CF who were either born since 1968
or before 1968 and still were alive in 1977. Death certification
data up to the end of 1995 were used. It was accepted that
ascertainment would be incomplete for the cohorts from 1990
either because some patients had not yet been diagnosed or due
to delays inherent to the data collection methods [6]. Strict
confidentiality was maintained and the identity of individuals
was known only to the corresponding consultant paediatrician
or adult physician and the nonmedical coordinator of UKCFS.
All data released from UKCFS were aggregated and anonymous.
In the present study, the data held in 1997 were supplemented
by data from all death certificates for UK residents from 1996
up to the end of 2003 in which CF or any of its synonyms were
mentioned (International Classification of Diseases (ICD)-9
codes 2270, 7770 and 7484; and ICD-10 codes E84.0, E84.1,
E84.8 and E84.9). Prior to version 6, introduced in 1968, ICD
did not separate CF from other diseases of the pancreas, so
death certification data was unreliable. The legal definition of
the minimum term for a stillbirth/neonatal death changed in
1996 from 28 to 24 weeks. The legal definition of a neonatal
death was used, which was relevant for one case.
Death certification data were linked to the UKCFS database
only using date of birth and sex. For the purposes of mortality
calculation it is only necessary to record one of any duplicate
matches. Where there was no match for death certificate data,
checks were made by contacting the certifying physician and
the data were corrected where necessary. Dead patients not
previously known to UKCFS were included as new cases,
unless positive evidence was found of their ineligibility, such
as foreign residents who died while temporarily in the UK, e.g.
visiting relatives or requesting a transplant.
The age/sex structure of the 2003 mid-year CF population of
o12 yrs of age is known directly. To estimate the numbers in the
2003 population of ,12 yrs of age, the total UK live births for
each year were found first. For these data, the CF births could be
estimated using an incidence of one in 2,381 (as reported in the
present study). The survival of each of these cohorts up to 2003
was presumed to follow the survival of the 1992–1994 cohort,
which leads directly to the estimated numbers surviving.
Incidence was only calculated for the period 1968–1987 due to
concerns regarding later under-ascertainment.
Cohort survival was calculated using the life table method and
current survival was calculated by applying the age/sex-
specific mortality rates for 1 yr successively to a hypothetical
birth cohort [10]. For the left-truncated survival, the total UK
live births were known for each period and therefore the total
CF births could be inferred using the incidence. The survey
data gave the size of the CF population that survived to a
specific age; the proportion of those who survived follows. The
remaining years survival was calculated using the life table
method. The data for the two sexes were pooled due to small
numbers in the older age groups.
RESULTS
Deaths
There were 1,066 deaths from 1996–2003, at a mean (range) of
133 (120–148) deaths?yr
-1
. In the cohorts born since 1968 there
were 872 deaths, 432 (49%) males in the same time period.
Population
Table 1 gives an estimate of the size of the mid-2003 UK CF
population. The size of the age group 0–9 yrs was estimated
based on extrapolations from the UK live births and the age
group o10 yrs from data held. These data form the denomi-
nator in the current survival calculations. The 1992 population
is given as 6,740.
Incidence
The extra cases found through the present study have led to a
1.4% increase in the previous incidence estimate for 1968–1987
from one in 2,416 [6] to one in 2,381 live births (6,474/
15.4610
6
).
Survival
The survival of 3-yr cohorts of male and female patients born
in the period 1968–1994 is given in figures 1a and b, with
corresponding hazard rates in table 2. The updated [11]
truncated survival in 3-yr cohorts for CF patients born in the
period 1947–1970 is given in figure 2. The current survival for
TABLE 1
Mid-2003 cystic fibrosis population by age and sex
0–,11–,55–,10 10–,15 15 16 17–,25 25–,35 35–,45 45–55 .55 Total
Male 140 550 700 725 152 143 992 672 318 40 7 4439
Female 140 550 700 634 128 140 802 479 221 39 12 3845
Total 280 1100 1400 1359 280 283 1794 1151 539 79 19 8284
% 3.4 13.3 16.9 16.4 3.4 3.4 21.7 13.9 6.5 1.0 0.2 100.0
The size of the 0–9-yrs-old-age group was estimated from population births and survival data. The size of the age groups of o10 yrs of age was based on data held by
the UK Cystic Fibrosis Survey.
J.A. DODGE ET AL. CF SURVIVAL IN THE UK
c
EUROPEAN RESPIRATORY JOURNAL VOLUME 29 NUMBER 3 523

males and females is given in figure 3. An abridged expecta-
tion of life table is given in table 3.
DISCUSSION
The results presented in the current paper show that the
continued improvement in survival anticipated from previous
results is occurring. The median expectation of life for the CF
population for 2000–2003 estimated from the current survival
calculations averages ,40 yrs (fig. 3). These calculations
assume that the current age-specific mortality rates will
continue. However, their continued improvement, as reflected
in table 2, suggests that an estimated median survival of 50 yrs
[12] for the birth cohort of the year 2000 remains likely.
The small number of death certificates of individuals born
prior to 1996 who were not known to UKCFS and previous
experience of the active surveillance in uncovering deaths not
reported via the certification authority, confirm that these data
should not be overinterpreted. During the active surveillance
period, great care was taken to avoid duplicating cases. The
subsequent merging of post-1996 death data is not entirely
satisfactory, since patients in the UKCFS database were
identified only by sex and date of birth. It is possible that
some existing cases marked as ‘‘deceased’’ were new cases and
some deceased marked as ‘‘new’’ were already in the data set,
perhaps under another name. However, the follow-up enqui-
ries and discussion with the relevant physician about new
deceased cases should have almost eliminated this risk. The
numbers are certainly small, may partially balance out and do
not contribute any important errors to these results.
The effects of the genuinely new cases previously unknown to
UKCFS are to increase previous estimates of the population
size and to slightly improve the historical survival. The effects
may be seen by reference to previous work: for example, the
1992 population is now given as 6,740 compared with a
previous count of 6,499 [6] and an earlier projection of 6,000 [7].
After excluding deaths among individuals of other national-
ities, newly or temporarily resident in the UK at the time of
death, and misdiagnoses, the remaining cases new to UKCFS
suggest that there are still patients with CF born before 1995
who were not identified by the survey. Nearly all of the new
cases were late diagnoses, either presenting with an atypical
history or found by family case studies. Whatever the reasons
for being unknown to UKCFS, the clear implication is that
there are still some unreported cases that could affect these
data. In terms of the survival data, a proportion, albeit small, of
the cohort-by-cohort increase can be attributed to a greater
ascertainment of late-diagnosed, milder cases. All patients
included here have CF. If there is to be any true appreciation of
trends in survival, it is important that criteria for diagnosis are
consistent and that patients with CF transmembrane conduc-
tance regulator-related disorders, such as isolated obstructive
azoospermia, which do not meet the diagnostic criteria of CF
and are not known to have an impact on life expectancy, are
excluded from consideration.
The previously noted pattern of linear descent of the survival
curves continues, following the addition of the further data
(fig. 1). The historical better early survival of males with CF is
much less apparent, although the survival by sex differs
markedly for cohorts born before 1987. It is still not clear
whether this is a cohort effect or whether adult females
inherently have a worse survival than males. As the age at
which the survival curves separate has increased recently,
reduction of the adult sex gap may continue.
The truncated survival curves shown in figure 2 (truncated as no
data was available for the older cohorts to deduce their shape
before 1968) show that a steadily increasing proportion is
surviving into their forties and beyond. The characteristics,
evolving problems and outlook for these long-surviving patients
are the subject of ongoing international studies [13, 14].
Specific survival data that may help in informing patients and
their carers are given in table 3. Death from CF in the first decade
of life is now rare [15]. This is presumably related to steadily
improving clinical management. Earlier cohorts show a striking
reduction in deaths in the first year of life, which was associated
with the (now almost universal) survival of infants with
meconium ileus resulting from improved neonatal management
[6, 7] (figs. 1 and 2). The post-infancy rate of attrition depicted in
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FIGURE 1. UK cystic fibrosis population. Proportion of a) males and b) females of each 3-yr cohort surviving until 2003. &: 1968–1970; #: 1971–1973; m: 1974–1976;
h: 1977–1979;
¤: 1980–1982; e: 1983–1985; n: 1986–1988; $: 1989–1991; ,: 1992–1994.
CF SURVIVAL IN THE UK J.A. DODGE ET AL.
524
VOLUME 29 NUMBER 3 EUROPEAN RESPIRATORY JOURNAL

the cohort survival curves has consistently flattened out,
suggesting that with that exception, no single new therapeutic
intervention can be identified as a major reason for the improved
survival. In 1968 in England and Wales, there were 118 deaths
attributable to CF in children aged 28 days to 16 yrs old,
compared with 75 in 1985 and 15 in 2000 [8].
This makes the cohort effect the major determinant of survival
and much stronger than sex. Occasionally, CF patients die
from unrelated causes, such as road traffic accidents. One such
TABLE 2
Cohort survival of the UK cystic fibrosis (CF) population by sex based on data held to the end of 2003
Year of birth
1968–1970 1971–1973 1974–1976 1977–1979 1980–1982 1983–1985 1986–1988 1989–1991 1992–1994
Males
CF births n 592 545 482 469 534 472 467 482 396
Age yrs
0–,1 213.1 (114) 182.2 (91) 111.7 (51) 77.5 (35) 47.9 (25) 54.5 (25) 23.8 (11) 18.8 (9) 22.9 (9)
1–,5 18.4 (34) 15.3 (27) 10.7 (18) 11.2 (19) 8.5 (17) 5.7 (10) 2.8 (5) 3.2 (6) 0.6 (1)
5–,10 19.4 (41) 23.8 (48) 18.8 (37) 10.9 (22) 8.3 (20) 4.6 (10) 3.1 (7) 2.6 (6) 0 (0)
10–,15 33.9 (63) 25.8 (46) 19.5 (35) 11.5 (22) 9.1 (21) 7.6 (16) 5.9 (13) 4.3
#
(5) 1.5
#
(1)
15–,20 33.8 (53) 36.7 (56) 29.6 (47) 24.6 (43) 19.5 (42) 12.8
#
(17) 2.7
#
(3)
20–,25 39.8 (52) 42.3 (53) 30.0 (41) 41.7
#
(52) 26.4
#
(27)
25–,30 42.4 (45) 45.3 (40) 50.6
#
(32)
30–,35 54.1
#
(31) 15.3
#
(7)
Females
CF births n 530 514 434 419 439 461 446 418 363
Age yrs
0–,1 190.0 (92) 155.1 (74) 901.6 (38) 87.1 (35) 61.0 (26) 39.8 (18) 24.9 (11) 14.4 (6) 13.9 (5)
1–,5 28.3 (47) 25.6 (43) 20.3 (31) 13.3 (20) 9.9 (16) 5.7 (10) 1.7 (3) 3.0 (5) 2.1 (3)
5–,10 41.8 (74) 27.4 (51) 29.4 (50) 23.8 (41) 16.3 (31) 8.0 (17) 6.5 (1) 3.5 (7) 5.1 (6)
10–,15 38.7 (56) 27.8 (45) 24.9 (37) 16.7 (26) 16.5 (29) 13.9 (28) 7.8 (1) 6.0
#
(6) 0
#
(0)
15–,20 51.9 (60) 38.6 (53) 44.5 (56) 39.1 (53) 27.3 (43) 28.7
#
(36) 6.9
#
(7)
20–,25 54.2 (48) 34.1 (40) 51.9 (51) 37.2 (35) 38.0
#
(28)
25–,30 55.0 (37) 50.6 (47) 27.9
#
(22)
30–,35 53.5
#
(19) 27.2
#
(11)
Data presented as hazard rate, which is the instantaneous mortality rate, per thousand, with the number of deaths in parentheses, unless otherwise stated. Censored data
with ,100 life yrs of observation and ,10 deaths have been omitted. The standard error of the hazard rate for all the 0–1-yr-old age groups is ,10 per thousand, for the
1–5-yrs-old group it is approximately four per thousand rising to six per thousand for the 30–35-yrs-old group.
#
: data subject to censoring.
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FIGURE 2. Left-truncated survival curves up to 2003 of the UK cystic fibrosis
population born in the period 1947–1970 in 3-yr cohorts. &: 1947–1949; #: 1950–
1052; m: 1953–1955; h: 1956–1958;
¤: 1959–1961; e: 1962–1964; $: 1965–
1967; n: 1968–1970.
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% surviving
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FIGURE 3. Current survival UK cystic fibrosis population by sex, 2003. #:
males; $: females.
J.A. DODGE ET AL. CF SURVIVAL IN THE UK
c
EUROPEAN RESPIRATORY JOURNAL VOLUME 29 NUMBER 3 525

instance during the period covered here is known but, unless
CF was mentioned on the death certificate, this would not be
the case. However, such deaths would be few, would have the
same background mortality as the general age-matched
population and would not obscure the observation that
survival of people with CF continues to improve.
The data for the expectation of life may lead to more realistic
life insurance being made available to people with CF
phenotype. Conversely, these results should lead to a lower
benefit being available for an impaired life annuity.
Comparisons with other studies
A proper comparison with the results from other published
data sets presents serious technical and methodological
problems. As these data sets do not conform to the WHO
standard of a total defined population, a noncohort analysis is
required. The results from these analyses are frequently
misinterpreted, as comparisons are made using relative risks
(or odds ratios) with insufficient explanation [16]. Other
examples of problems in interpreting CF survival data are
available [17]. However, survival data from large national
registries which, unlike UKCFS, are based on information only
from specialist clinics and therefore have a selection bias, show
broadly comparable and gratifying trends [18, 19].
Conclusions
1) The total population study shows that survival with cystic
fibrosis continues to improve in the UK and, by implication, in
many other countries too.
2) Continued growth of the adult cystic fibrosis population by
,145 patients per annum has national and local implications
for healthcare provision and training of staff to manage adult
cystic fibrosis clinics. The annual population increase would
approximate to the size of a moderately large adult clinic.
3) The expectation of life data should be of value to life
insurance companies in calculating risks and returns on life
annuities for people with cystic fibrosis.
4) Previously published predictions of a mean survival of
.50 yrs of age, for infants with cystic fibrosis recently born in
the UK, continue to look realistic, even in the absence of
proven effective therapy aimed at correcting the basic cystic
fibrosis defect.
ACKNOWLEDGEMENTS
These data were collected over many years with the generous
assistance of over 1,500 carers of people with cystic fibrosis.
REFERENCES
1 Manual of mortality analysis. Geneva, World Health
Organization (Division of Health Statistics), 1977; pp. 2–3.
2 Brunecky Z. The incidence and genetics of cystic fibrosis.
J Med Genet 1972; 9: 33–37.
3 Ten Kate LP. Cystic fibrosis in the Netherlands. Int J
Epidemiol 1977; 6: 23–34.
4 Selander P. The frequency of cystic fibrosis of the pancreas
in Sweden. Acta Paediatr 1962; 51: 65–67.
5 Cystic fibrosis in the United Kingdom 1977–85, an improv-
ing picture. British Paediatric Association Working Party on
Cystic Fibrosis. BMJ 1988; 297: 1599–1602.
6 Dodge JA, Morison S, Lewis PA, et al. Incidence, popula-
tion, and survival of cystic fibrosis in the UK, 1968-95. Arch
Dis Child 1997; 77: 493–496.
7 Dodge JA, Morison S, Lewis PA, et al. Cystic fibrosis in the
United Kingdom, 1968–1988: incidence, population and
survival. Paediatr Perinat Epidemiol 1993; 7: 157–166.
8 Panickar JR, Dodd SR, Smyth RL, Couriel JM. Trends in
deaths from respiratory illness in children in England and
Wales from 1968–2000. Thorax 2005; 60: 1035–1038.
9 The molecular genetic epidemiology of cystic fibrosis –
Report of a joint meeting of WHO/ECFTN/ICF(M)A/
ECFS. Geneva, WHO Human Genetics Programme, 2004;
p. 24. Available at http://whqlibdoc.who.int/hq/2004/
WHO_HGN_CF_WG_04.02.pdf.
10 Armitage P, Berry G. Statistical methods in medical
research. Oxford, Blackwell Science Ltd, 1994; p. 470.
11 Lewis PA, Morison S, Dodge JA, et al. Survival estimates
for adults with cystic fibrosis born in the United Kingdom
between 1947 and 1967. Thorax
1999; 54: 420–422.
12 Jannot A-S. Examples of statistical analysis of epidemiolo-
gical data sets. MPhil Dissertation. University of Bath,
Bath, 2000.
13 Dodge JA, Milla CE, Warwick WJ. A study of cystic fibrosis
(CF) associated diseases of aging. J Cyst Fibros 2004; 3: S122.
14 University of Minnesota. Aging with Cystic Fibrosis:
Organization of an International Project. http://www.med.
umn.edu/agingcf/. Date last updated: November 5, 2004.
15 Dodge JA, Lewis PA. Cystic fibrosis is no longer an
important cause of childhood death in the United
Kingdom. Arch Dis Child 2005; 90: 547.
16 Bradford Hill A. Further fallacies and difficulties.
Proportional rates. In: A short textbook of medical
statistics. Kent, Hodder and Stoughton, 1977; p. 266.
17 Lewis PA. Inferences for health provision from survival
data in cystic fibrosis. Arch Dis Child 1998; 79: 297–299.
18 Cystic Fibrosis Foundation, Patient Registry. Annual
Report 2004. Bethesda, CFF, 2004.
19 McCormick J, Sims EJ, Green MW, Mehta G, Culross F,
Mehta A. Comparative analysis of Cystic Fibrosis Registry
data from the UK with USA, France and Australasia. J Cyst
Fibros 2005; 4: 115–122.
TABLE 3
Abridged expectation of life by sex: 2003
Age yrs Expected mean age of death yrs
Males Females
0 42.62 36.89
1 43.12 37.33
2 43.12 37.33
3 43.25 37.44
4 43.25 37.44
5 43.38 37.55
10 43.63 37.76
15 44.18 38.39
20 45.41 40.43
25 48.66 44.34
30 52.67 49.40
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