Trends in COPD. 2003/1
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Chronic obstructive pulmonary disease (COPD) is a relatively
new name for an old condition. As a diagnostic category in hospital
admissions and mortality data, the label "chronic airways
obstruction" was first established in 1979 with the introduction
of ICD 9, largely replacing chronic bronchitis and emphysema.
In ICD 10, introduced for coding admissions from April 1996 and
from 2001 for mortality, the term used is "Other chronic
obstructive pulmonary disease". The WHO predicts that COPD
will rise up the rankings of chronic disease prevalence from 12th
to 5th place by 2020 world wide, but the trends in the UK tend
not to follow that global pattern.
Prevalence
There are few data on the prevalence of COPD in the UK. The Health
Survey for England 1996 reported on relative lung function (see
notes) and chronic respiratory symptoms in the adult population.
The prevalence of low FEV1 values was 11% in men and
8% in women (see footnote) while the prevalence of chronic cough
or phlegm production was 19% in men and 14% in women. The General
Household Survey records self-reported diagnoses of chronic bronchitis
and emphysema. These showed a far lower prevalence of 0.9% in
men and 0.7% in women in 2001 which indicates that much early
disease is unrecognised.
GP consultations
Factsheet 96/3 reported patient-consulting rates from the three
national Morbidity Surveys in General Practice which showed no
increase between 1971 and 1991 for patients diagnosed with chronic
bronchitis. Analysis of the General Practice Research Database
(GPRD) showed a prevalence of GP consultations for COPD of 1.6%
in men and 1.4% in women in 1997. There was a small upward trend
in women from 1990-97 and a levelling off in men during that period.
However, these figures will not include those who have COPD but
without symptoms of sufficient severity to report that year.
Figure 1:Seasonal variations in GP
consultations and prescribing for COPD
The General Practice Research Database also shows the predicted
winter seasonality of consultations for COPD. In contrast, prescribing
for COPD-like symptoms is constant throughout the year except
during the Christmas/New Year period.
Hospital admissions
Figure 2: Admissions for chronic obstructive
pulmonary diseases, all ages
Most admissions for chronic obstructive pulmonary diseases are
coded as COPD or COAD, rather than chronic bronchitis or emphysema.
Figure 3: Admission rates for COPD
by age
Admission rates for all COPD diagnoses combined have increased
across all age groups over the last decade and this is due largely
to factors other than a diagnostic shift from asthma to COPD.
Figure 4: Trends in admission rates
for COPD in males and females all ages.
The increase in admissions is slightly greater in females than
in males but the trends are broadly similar. COPD admissions as
a percentage of all admissions have also increased steadily from
0.5% in 1991 to 1% in 2000.
Mortality
Figure 5: Trends in age-adjusted mortality
rates from COPD in males and females
last twenty years in males from 1070 to 634 per million (largely
in those over the age of sixty five). In contrast rates have increased
in females overall from 230 to 323 per million over the same period.
Figure 6: Trends in deaths in females
from COPD by age
This increase in females has been in the 65-84 years age group
while the rates at younger ages have fallen slightly. It is notable
that there is a greater divergence in trends in COPD mortality
between the sexes than in admissions or GP consultations. This
might be due to a sex difference in the pathology of the airway
inflammatory process, differences in perception of symptom severity
or in the natural history in the terminal stages of the disease.
The geographical pattern for mortality tends to concentrate over
industrialised areas, but is broadly similar between males and
females (LAIA factsheet 96/1).
Summary
-
The prevalence of diagnosed COPD is about 1.5% in the UK
and prevalence of reduced lung function is about 10%.
-
COPD continues to be responsible for over 90,000 hospital
admissions a year which, with an average duration of stay
of 11 days, means nearly a million hospital bed days per year.
-
Mortality continues to rise in women but has fallen in men.
-
The disparity between the trends for mortality, hospital
admissions and GP consultations between the sexes remains
unexplained.
Footnote
Forced Expiratory Volume in the first second (FEV1).
This is the volume that can be expelled in the first second of
forced expiration, starting from a full inspiration. A low FEV1
is a marker of airway narrowing, indicative of COPD, asthma or
other obstructive lung diseases. 'Low' in this case meant that
people were less than 1.64 standard deviations lower than the
predicted level based on a reference population (that is, within
the lowest expected 5% of the predicted population).
Sources
Health Survey for England 1996
General Household Survey 2000
Soriano JB et al. Recent trends
in physician diagnosed COPD in women and men in the UK. Thorax
2000; 55: 789-794
ONS Mortality Statistics
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