The epidemiology of medical treatment for glaucoma and ocular hypertension in the United Kingdom: 1994 to 2003.

Abstract

To study trends in the prevalence of being treated for glaucoma and ocular hypertension from 1994 to 2003, and to examine factors determining treatment in 2002.
Computerised data (the DIN-LINK database) from 131 general practices across the United Kingdom, in which half a million patients aged 40 years or more were registered annually, were used. On average 10 000 patients were treated for glaucoma and ocular hypertension annually.
Prevalence of being treated for glaucoma and ocular hypertension increased from 1.7% in 1994 to 2.3% in 2003. Those aged 85 years or more were 13 times (95% CI 12.2 to 13.8) more likely to be treated than those aged 40-64 years. Men were more likely to be treated than women (OR 1.24, 95% CI 1.19 to 1.28). Subjects "hard pressed" were less likely to be treated than "wealthy achievers" (OR 0.92, 95% CI 0.86 to 0.99). While use of topical beta blocker only medications has declined since 1995, use of topical prostaglandins and combination therapies has increased. In 2003, use of prostaglandins overtook beta blocker only medications.
Prevalence of being treated for glaucoma has increased over time, and rises with age. Differences in treatment by sex and social status could be explained by use of or access to health care or by underlying prevalence of disease. Trends in treated glaucoma emphasise the shift from use of topical beta blockers to newer therapies.

Full text

Page 1

EXTENDED REPORT
The epidemiology of medical treatment for glaucoma and
ocular hypertension in the United Kingdom: 1994 to 2003
C G Owen, I M Carey, S De Wilde, P H Whincup, R Wormald, D G Cook
............................................................... ............................................................... .
See end of article for
authors’ affiliations
.......................
Correspondence to:
Dr Christopher G Owen,
Division of Community
Health Sciences, St
George’s, University of
London, Cranmer Terrace,
London SW17 0RE, UK;
cowen@sgul.ac.uk
Accepted for publication
7 March 2006
.......................
Br J Ophthalmol 2006;90:861–868. doi: 10.1136/bjo.2005.088666
Aims: To study trends in the prevalence of being treated for glaucoma and ocular hypertension from 1994
to 2003, and to examine factors determining treatment in 2002.
Methods: Computerised data (the DIN-LINK database) from 131 general practices across the United
Kingdom, in which half a million patients aged 40 years or more were registered annually, were used. On
average 10 000 patients were treated for glaucoma and ocular hypertension annually.
Results: Prevalence of being treated for glaucoma and ocular hypertension increased from 1.7% in 1994
to 2.3% in 2003. Those aged 85 years or more were 13 times (95% CI 12.2 to 13.8) more likely to be
treated than those aged 40–64 years. Men were more likely to be treated than women (OR 1.24, 95% CI
1.19 to 1.28). Subjects ‘‘hard pressed’’ were less likely to be treated than ‘‘wealthy achievers’’ (OR 0.92,
95% CI 0.86 to 0.99). While use of topical b blocker only medications has declined since 1995, use of
topical prostaglandins and combination therapies has increased. In 2003, use of prostaglandins overtook
b blocker only medications.
Conclusion: Prevalence of being treated for glaucoma has increased over time, and rises with age.
Differences in treatment by sex and social status could be explained by use of or access to health care or
by underlying prevalence of disease. Trends in treated glaucoma emphasise the shift from use of topical b
blockers to newer therapies.
G
Primary open angle glaucoma (POAG) (accounting for 90–
96% of all glaucomas)4 5has been estimated to affect 230 000
people (3%) in England and Wales aged over 65 years.6This
puts a considerable burden on secondary care services (the
hospital eye service) that manage patients with glaucoma.7
Management of glaucoma is palliative rather than curative
and involves pharmaceutical and/or surgical management to
reduce intraocular pressure (IOP). Evidence from clinical
trials has shown that pharmaceutical reduction of IOP delays
glaucomatous progression.8Topical b blockers have formed
the mainstay of glaucoma management for the last 20 years
or so, although concerns about bronchial side effects have
been raised, especially in the elderly where glaucoma is more
prevalent.9–11New modes of topical treatment for glaucoma
and ocular hypertension have emerged since 1995, including
prostaglandins, carbonic anhydrase inhibitors, a2 agonists,
and combination therapies.12Although the uptake of these
treatments has been described in Scotland from 1994 to
1999,13 14little is known about the therapeutic cost and
prescribing patterns for glaucoma medications elsewhere in
the United Kingdom.
General practice databases form a unique source of
longitudinal population based clinical information on health
service use and the prevalence and management of diagnosed
disorders such as glaucoma and/or ocular hypertension,
allowing the incidence, prevalence, and risk factors asso-
ciated with treatment to be explored. In this paper we use
information from a large scale general practice database
(DIN-LINK) to provide information on treatment for glau-
coma in the United Kingdom. The DIN-LINK database is used
to (i) document trends in prevalence of treated glaucoma, (ii)
examine who is treated by age, sex, socioeconomic position,
and region, and (iii) document changes in drugs used.
laucoma is the leading cause of irreversible vision loss
worldwide and is of major public health importance,
leading to loss of mobility and independence.1–3
METHODS
The DIN-LINK database
DIN-LINK is an ongoing anonymised computerised UK
primary care database from practices that use iSOFT
(formerly Torex) software from 1989 onwards. This report
is based on 131 practices that run an updated version of the
software used in an earlier version of the database, previously
described.15 16We have outlined methodology for identifying
Table 1
treatment for glaucoma
Read codes used in the DIN-LINK database for
Drug groupRead codes
(i) b blockers only k83 (betaxolol hydrochloride), k85 (cartelol
hydrochloride), k8b (metipranolol), k8f
(timolol maleate), k8g (levobunolol
hydrochloride)
k8i (latanoprost), k8n (travoprost), k8o
(bimatoprost)
k84 (carbachol), k86 (demecarium bromide),
k89 (ecothiopate iodide), k8c (physostigmine
sulphate), k8d (pilocarpine hydrochloride),
k8e (pilocarpine nitrate)
k82 (adrenaline), k88 (dipverfine
hydrochloride), k8a (guanethidine
monosulph), k8j (brimonidine tartrate)
k81 (acetazolamide), k87 (dichlophenamide),
k8h (dorzolamide), k8l (brinzolamide)
k8k (dorzolamide + timolol)
(ii) Prostaglandins only
(iii) Cholinergic agents
(iv) Sympathomimetics
(v) Carbonic anhydrase
inhibitors only
(vi) Carbonic anhydrase
inhibitors and b blocker
(vii) Prostaglandins and
b blockers
k8m (latanoprost + timolol)
Abbreviations: ACORN, A Classification of Residential
Neighbourhoods; IMD, index of multiple deprivation; IOP, intraocular
pressure; POAG, primary open angle glaucoma
861
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good quality data in DIN-LINK,16and the selected practices
had to provide at least 5 years of continuous high quality
data.
The completeness and accuracy of DIN-LINK data have
been demonstrated, by comparisons with other national data
sources. The practices and general practitioners (GPs) in DIN-
LINK are as comparable to the UK norm as the practices and
GPs in other GP research databases.15 16Morbidity and drug
data are coded using Read codes. Subjects’ postcodes in the
database are associated with two sociodemographic indica-
tors at a small area level—the index of multiple deprivation
(IMD) and the ACORN index. IMD was produced by the
office of the deputy prime minister from the 2001 census,17
and ranks census ‘‘super output areas’’ in England (average
1500 residents) from most deprived to least. ACORN18also
uses data from the 2001 census to classify postcodes. Multiple
levels of aggregation of the index are available, but
commonly, the most aggregated level—a five level classifica-
tion from ‘‘wealthy achievers’’ through to ‘‘hard pressed’’ is
used. Out of the 131 practices, ACORN scores were available
for most patients in 125 of these, while IMD was available for
104 practices (three practices in Scotland and two in Wales
were excluded from the IMD linkage). Practices were also
classified by their region.
Patient selection
We selected patients aged 40 years or more who were fully
registered with a practice on 31 December of a given year, and
had been continuously registered for at least 6 months before
this date. This approach has been used in our earlier work
and follows the methods used in key health statistics.19 20This
resulted in a denominator of approximately 500 000 patients
annually, from 1994 to 2003. Although glaucoma or ocular
hypertension is a secondary care diagnosis, pharmaceutical
management for glaucoma can be picked up using primary
care databases with a high degree of accuracy, as continuing
prescriptions for glaucoma medications are issued in primary
care irrespective of the completeness of recording of
secondary care diagnosis. Treatment for glaucoma or ocular
hypertension was defined as the presence of a coded entry for
a prescription for glaucoma before 31 December in the year of
interest; codes are listed in table 1. In this paper we focus on
treatment for glaucoma or ocular hypertension because
diagnostic codes for glaucoma are not consistently reported.
We extracted data for patients on age, sex, registered
practice, NHS region, smoking status, ACORN score, IMD
index, and number of consultations with their general
practitioner per year. Data were also available on the type
of medication prescribed and classified into seven categories
(table 1): (i) b blockers, (ii) prostaglandins, (iii) cholinergic
agents, (iv) sympathomimetics, (v) carbonic anhydrase
inhibitors, (vi) carbonic anhydrase inhibitors and b blockers,
(vii) prostaglandins and b blockers. All were topical medica-
tions except for category (v) which included oral and injected
preparations.
Analysis
We examined the period prevalence of recorded treatment for
glaucoma annually from 1994 to 2003, by age group ( 40–64,
65–74, 75–84, >85 years), for males and females separately.
The percentage of those treated for glaucoma on different
categories of active treatment listed (i) to (vii) above,
including combination therapies, were examined by year
for males and females separately. Patients receiving a b
blocker or prostaglandin monotherapy therapy were counted
in the ‘‘only’’ category. Combined percentages are greater
than 100% as categories are not mutually exclusive. Odds
ratios (ORs) were derived from logistic regressions to identify
factors associated with treatment for glaucoma in 2002,
including, age, sex, geographic region (north, mid, south),
markers of socioeconomic status (ACORN and IMD indices),
and propensity to consult. Basic ORs adjusted for age, sex,
practice (except region and sociodemographic indicators
which are adjusted for age and sex only), and ORs adjusted
for all factors (except ACORN and IMD which are not
adjusted for each other) were calculated. The year 2002 was
chosen because of the large number of patients and to give
contemporary influences on treatment. Similar ORs were
observed when data from 1994 were used (data not
presented).
RESULTS
Period prevalence of treatment for glaucoma
From 1994 to 2003, nearly half a million patients aged
40 years or more were registered annually (table 2) with the
131 practices. The percentage of the population treated for
glaucoma increased gradually over time from 1.7% in 1994
for both sexes, to 2.3% in males and 2.4% in females in 2003
12.0
10.0
8.0
6.0
4.0
2.0
0.0
Year
A
40–64
65–74
75–84
85–
Percentage
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
12.0
10.0
8.0
6.0
4.0
2.0
0.0
Year
B
Percentage
1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
Figure 1
treated for glaucoma in each year from
1994 to 2003: (A) men and (B) women.
Percentage of subjects
862Owen, Carey, De Wilde, et al
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(table 2). The proportionate rise in treatment for glaucoma
was similar in younger and older age groups, despite the
prevalence of treatment being far greater in older age groups
(fig 1, table 2). In those aged 40–64 years, 0.6% of males were
treated in 1994 rising to 0.8% in 2003 (a rise of 37%), for
females the prevalence rose from 0.5% to 0.7% (38% increase)
over a similar time period (fig 1, table 2). In those aged
85 years or more, 8.3% and 11.3% were treated in males
respectively (a rise of 36%), a slightly greater increase (57%)
was observed in females (from 6% to 9.5%) (fig 1, table 2).
Changes in treatment of glaucoma
Figure 2 and table 3 show the proportions of treated patients
receiving different types of therapy for glaucoma from 1994
to 2003, for men and women separately. Decreases in
prescribing of topical b blocker only medications since 1995
have been accompanied by rising levels of prostaglandins and
combination therapies; in 2003 for the first time topical
prostaglandins were prescribed more frequently (59% of
prescriptions) than b blockers (50%) in both men and women
(fig 2, table 3). Although the prescribing of b blocker only
medications has declined, the decline in b blocker therapy is
less as there has been an increase in combination therapies
(fig 2, table 3). Other types of treatment were prescribed for
less than 30% of patients. It is notable that the use of
cholinergic agents and sympathomimetic therapies (includ-
ing older sympathomimetic and newer a2agonist therapies)
has also declined. Decreases in the use of carbonic anhydrase
inhibitors since the late 1990s coincide with the introduction
of topical prostagladins and the emergence of topical
therapies combining b blockers and carbonic anhydrase
inhibitors. Grouping carbonic anhydrase inhibitors into
systemic and topical medications shows the rapid deccrease
in the use of systemic preparations; in 1994 all patients
(n=219) received systemic carbonic anhydrase inhibitors, in
1995, 88% (n=243/276) were treated with systemic prepara-
tions, in 2002 this had fallen to 9% (n=124/1402).
Factors influencing treatment for glaucoma and ocular
hypertension in 2002
There was a steep increase in prescribing treatment for
glaucoma with age; those 85 years or more were 13 times
(95% CI 12.2 to 13.8) more likely to be treated than those
aged 40–64 years (table 4). Men were more likely to be
treated than women (OR 1.24, 95% CI 1.19 to 1.28) once sex
differences in the distribution of age were adjusted for
(table 1). The ACORN index showed that those from less
privileged areas were less likely to be treated; those ‘‘hard
pressed’’ were less likely to be treated than ‘‘wealthy
achievers’’ (OR 0.92, 95% CI 0.86 to 0.98). There was no
evidence of a trend in being treated across IMD scores,
although treatment in patients classified as ‘‘most deprived’’
was marginally less than in those ‘‘least deprived’’ (OR 0.92,
0.84 to 1.02). There was no evidence of a regional trend in
treatment. Smokers were less likely to be treated and ex-
smokers more likely to be treated than non-smokers.
Increased consultations were associated with higher levels
of treatment. Odds ratios were not materially altered when
Table 2
Period prevalence of being treated for glaucoma in DIN-LINK for men and women, 1994 to 2003
19941995 199619971998 19992000 2001 20022003
Men
Number*
r?
%
40–64 years
Number
r
%
65–74 years
Number
r
%
75–84 years
Number
r
%
85+ years
Number
r
%
Women
Number
r
%
40–64 years
Number
r
%
65–74 years
Number
r
%
75–84 years
Number
r
%
85+ years
Number
r
%
174 130
2881
1.65
189 512
3239
1.71
208 551
3745
1.80
216 253
4036
1.87
231 085
4491
1.94
244 603
4886
2.00
246 219
5122
2.08
249 660
5323
2.13
253 600
5550
2.19
246 024
5532
2.25
121 012
732
0.60
131 959
849
0.64
145 438
989
0.68
151 094
1070
0.71
161 801
1194
0.74
171 361
1307
0.76
172 683
1328
0.77
175 267
1383
0.79
178 089
1422
0.80
172 341
1419
0.82
32 948
956
2.90
35 102
1011
2.88
37 906
1136
3.00
38 676
1188
3.07
40 803
1313
3.22
42 886
1397
3.26
42 768
1460
3.41
43 029
1484
3.45
43 660
1528
3.50
42 587
1534
3.60
16 160
859
5.32
18 069
1019
5.64
20 261
1189
5.87
21 195
1313
6.19
22 779
1463
6.42
24 209
1608
6.64
24 576
1743
7.09
25 028
1809
7.23
25 577
1901
7.43
25 127
1902
7.57
4010
334
8.33
4382
360
8.22
4946
431
8.71
5288
465
8.79
5702
521
9.14
6147
574
9.34
6192
591
9.54
6336
647
10.21
6274
699
11.14
5969
677
11.34
198 457
3366
1.70
214 511
3743
1.74
234 899
4350
1.85
241 846
4715
1.95
257 155
5187
2.02
270 981
5695
2.10
271 856
5928
2.18
274 176
6192
2.26
277 440
6448
2.32
267 794
6429
2.40
121 313
604
0.50
131 739
671
0.51
144 611
768
0.53
149 395
848
0.57
159 889
939
0.59
169 192
1026
0.61
170 567
1058
0.62
172 865
1092
0.63
175 828
1156
0.66
169 787
1174
0.69
39 586
934
2.36
41 623
1000
2.40
44 688
1115
2.50
45 094
1180
2.62
46 930
1288
2.74
48 736
1379
2.83
48 245
1429
2.96
47 920
1464
3.06
48 119
1488
3.09
46 633
1456
3.12
26 353
1154
4.38
29 083
1299
4.47
32 285
1560
4.83
33 372
1690
5.06
35 298
1848
5.24
37 171
2046
5.50
37 189
2127
5.72
37 397
2263
6.05
37 816
2372
6.27
36 644
2403
6.56
11 205
674
6.02
12 066
773
6.41
13 315
907
6.81
13 985
997
7.13
15 038
1112
7.39
15 882
1244
7.83
15 855
1314
8.29
15 994
1373
8.58
15 677
1432
9.13
14 730
1396
9.48
*Number of registered patients in year aged 40 years or more.
?r, number from number with history of glaucoma treatment in their electronic record.
Epidemiology of treated glaucoma and ocular hypertension 863
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the analysis was restricted to practices contributing data
throughout the study period.
DISCUSSION
The period prevalence of glaucoma treatment has risen
steadily since the mid-1990s and rises steeply with age.
Prevalence rates of treatment for glaucoma for different adult
age groups in the mid-1990s are consistent with a recent
meta-analysis of 24 studies (mostly published in the 1990s
with 53 874 subjects, including 999 with glaucoma) that
examined the prevalence of glaucoma in white populations,
ascertained by clinical examination (Rudnicka et al, personal
communication, 2005). Prevalence estimates from this review
were 0.7% (95% CI 0.3% to 1.4%) in those aged 40–64 years,
2.1% (0.6% to 7.4%) aged 65–74 years, 4.1% (0.9% to 17.6%)
aged 75–84 years, and 7.9% (1.2% to 36.5%) in those aged
85 years or more (estimates for comparable age groups
provided by study authors, Rudnicka et al, personal commu-
nication, 2005). The majority of the older population of
Britain are white,21hence comparing these prevalence rates
with a meta-analysis of white populations was considered
appropriate. While it is tempting to infer from this similarity
that most glaucoma patients are known to health services,
apparently refuting the finding from population studies that
half of glaucoma patients in the population remain unde-
tected,5 22–25patients receiving treatment for glaucoma will
include both those with glaucoma (mostly POAG)4 5and
those with ocular hypertension (a group at considerably
increased risk of developing the condition). Hence, our
estimate of the prevalence of treated glaucoma will tend to
overestimate the number with glaucoma. Conversely, the
number receiving treatment excludes those who have
borderline or early signs of the glaucoma who continue to
be monitored but remain untreated, and those who have had
successful surgery for glaucoma or non-progressive normal
tension glaucoma; this would act to underestimate the
number with disease.
The proportion of patients in the United Kingdom receiving
treatmentsolely for glaucoma or ocular hypertension is unclear.
It was difficult to rely on diagnostic codes for glaucoma to
examine this issue further as glaucoma diagnoses were
inconsistently recorded. Seventy per cent of diagnostic codes
werefor‘‘glaucoma’’(withnofurtherinformationastothetype
of glaucoma), 10% for ‘‘primary open angle glaucoma’’; the
100
90
70
80
60
40
50
30
20
0
10
Year of drug administration
Prostaglandin
β blocker
Cholinergic agent
Sympathomimetic
Carbonic anhydrase inhibitor
Carbonic anhydrase inhibitor and β blocker
Prostaglandin and β blocker
Percentage of treated male glaucoma patients
aged 40+ who receive different therapies
A
2003 2002 2001 20001999 1998199719961995 1994
100
90
70
80
60
40
50
30
20
0
10
Year of drug administration
Percentage of treated female glaucoma patients
aged 40+ who receive different therapies
B
20032002 200120001999 19981997 199619951994
Figure 2
glaucoma in DIN-LINK by year for
(A) men and (B) women, 1994 to
2003.
Type of treatment for
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Table 3
Type of treatment for glaucoma in DIN-LINK by year for men and women, 1994 to 2003
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Men
Number of registered age >40 years*
No
174 130
189 512
208 551
216 253
231 085
244 603
246 219
249 660
253 600
246 024
Number treated in year
No
2509
2769
3149
3347
3717
4036
4218
4375
4542
4568
%*
1.44
1.46
1.51
1.55
1.61
1.65
1.71
1.75
1.79
1.86
Type of treatment
b blockers only
No
2241
2466
2763
2879
3089
3246
3134
2929
2649
2,322
%?
89
89
88
86
83
80
74
67
58
51
Prostaglandins only
No
0
0
0
101
424
901
1366
1889
2347
2697
%?
0
0
0
3
11
22
32
43
52
59
Cholinergic agents (parasympathomimetics)
No
674
710
741
657
577
492
402
292
258
209
%?
27
26
24
20
16
12
10
7
6
5
Sympathomimetics (a agonists)
No
458
475
442
367
526
598
556
510
471
419
%?
18
17
14
11
14
15
13
12
10
9
Carbonic anhydrase inhibitors
No
92
129
484
766
933
948
817
770
692
688
%?
4
5
15
23
25
23
19
18
15
15
Carbonic anhydrase inhibitors and b blockers
No
0
0
0
0
0
106
241
362
442
482
%?
0
0
0
0
0
3
6
8
10
11
Prostaglandins and b blockers
No
0
0
0
0
0
0
0
0
118
237
%?
0
0
0
0
0
0
0
0
3
5
Women
Number of registered age >40 years
No
198 457
214 511
234 899
241 846
257 155
270 981
271 856
274 176
277 440
267 794
Number treated in year
No
2898
3162
590
3789
4,139
4541
4684
4893
5092
5109
%*
1.46
1.47
1.53
1.57
1.61
1.68
1.72
1.78
1.84
1.91
Type of treatment
b blockers
No
2530
2805
3127
3264
3458
3567
3384
3171
2904
2531
%?
87
89
87
86
84
79
72
65
57
50
Prostaglandins
No
0
0
0
97
469
1082
1615
2142
2667
3044
%?
0
0
0
3
11
24
34
44
52
60
Cholinergic agents (parasympathomimetics)
No
792
820
873
795
657
577
458
375
320
244
%?
27
26
24
21
16
13
10
8
6
5
Sympathomimetics (a agonists)
No
463
466
437
393
537
607
550
499
426
380
%?
16
15
12
10
13
13
12
10
8
7
Carbonic anhydrase inhibitors
No
127
147
536
798
945
971
816
749
721
714
%?
4
5
15
21
23
21
17
15
14
14
Carbonic anhydrase inhibitors and b blockers
No
0
0
0
0
0
126
275
391
456
478
%?
0
0
0
0
0
3
6
8
9
9
Prostaglandins and b blockers
No
0
0
0
0
0
0
0
0
114
249
%?
0
0
0
0
0
0
0
0
2
5
*Percentage of total registered.
?Percentage of number treated in year.
Epidemiology of treated glaucoma and ocular hypertension865
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