SUPPLEMENTARY INFORMATION

METHODS

Quality and Outcomes Framework

The Quality and Outcomes Framework (QOF)was introduced in April 2004 as a voluntary incentive scheme for UK general practices, rewarding them financially for the provision of quality care for chronic conditions.1,2 It contains groups of indicators against which practices score points according to their level of achievement, which then translate into financial rewards. The reporting requirements of the QOF are based entirely on Read Codes, which provide a coded thesaurus of clinical terms and enable clinicians to record patient findings and procedures in health and social care information technology systems across primary and secondary care.1,3,4

Lung function

Lung function grades are defined as: 1: ≥80% predicted; 2: 50% ≤ forced expiratory volume in 1 second (FEV1) 80% predicted; 3: 30% ≤ FEV150% predicted; 4: FEV130% predicted.5

Modified Medical Research Council scores

Modified Medical Research Council (mMRC) data were taken from both electronic patient records (routine data) and validated disease-assessment questionnaires (patient-reported data). Questionnaires were used for 11%of patients in this study, as these patients did not have a recorded mMRC score in their medical records. mMRC scores are defined as: 0: I only get breathless with strenuous exercise; 1: I get short of breath when hurrying on the level or walking up a slight hill; 2: I walk slower than people of the same age on the level because of breathlessness, or I have to stop for breath when walking at my own pace on the level; 3: I stop for breath after walking about 100 meters or after a few minutes on the level; 4: I am too breathless to leave the house or I am breathless when dressing or undressing.5

RESULTS

Patients

Table S1 shows baseline characteristics and demographics by cohort. In general these were similar across the three cohorts; however, the latest cohort (2007-2010) had fewer current smokers and more ex-/non-smoker than the earliest cohort (1997-2001). Patients in the latest cohort also had less severe lung function but more symptoms, compared with the earliest cohort.

Data on the comorbidities present in the overall population are presented in Table S2. The three most common comorbidities in this population were depression/anxiety (31%), asthma (20%) and ischaemic heart disease (18%).

Predictors of initial COPD treatment

Univariable analysis was used to identify predictors of treatment choice. For patients receiving their first therapy during the year prior to or atthe initial date of chronic obstructive pulmonary disease (COPD) diagnosis, patients with comorbid asthma were 4.1 times more likely to receive any initial COPD therapy and 5.5 times more likely to receive initial maintenance therapy than patients without comorbid asthma (Table S3). Patients with an annual rate of ≥3 exacerbations had 6.1 times higher odds of receiving any initial COPD therapy and 4.8 times higher odds of receiving initial maintenance therapy compared with patients with no exacerbations. Lung function grade and mMRC score were weaker predictors of initial COPD therapy choice (Table S3).

Analysis of the subgroup of patients who received their first therapy on the date of COPD diagnosis showed that in this population, unlike in the total population,comorbid asthma was not a predictor of being prescribed initial maintenance therapy (Table S3).Furthermore, an annual rate of ≥3 exacerbations was not predictive of either any initial therapy or initial maintenance therapy (Table S3).

REFERENCES

1.Health & Social Care Information Centre (HSIC). Quality and Outcomes Framework. Updated October 2014. Last accessed 14 January 2015.

2.Roland M. Linking physicians' pay to the quality of care - a major experiment in the United Kingdom. N Engl J Med 2004; 351: 1448‒1454.

3.British Medical Association. 2014/15 General Medical Services (GMS) contract quality and outcomes framework (QOF). Guidance for GMS contract 2014/15. Updated March 2014. Last accessed 29 October 2014.

4.Health & Social Care Information Centre (HSIC). Read Codes. Last accessed 16 January 2015.

5.Global initiative for chronic Obstructive Lung Disease (GOLD 2015). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Updated 2015. Last accessed 13 February 2015.

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Table S1. Patient baseline characteristics and demographics for each cohort

Cohort (initial date of COPD diagnosis)
Characteristics / 1997–2001
(n = 2,391) / 2002–2006
(n = 11,881) / 2007–2010
(n = 5,882)
Age, years, median (IQR) / 64 (57–70) / 66 (59–73) / 67 (60–75)
Gender, male n (%) / 1,209 (51) / 6,173 (52) / 3,127 (53)
Body mass index, kg/m2, median (IQR) / 25.7 (23–29) / 26.4 (23–30) / 26.7 (23–31)
Smoking status, n (%)
Non-smoker / 77 (3.2) / 519 (4.4) / 297 (5.0)
Smoker / 1,244 (52) / 5,505 (46) / 2,555 (43)
Ex-smoker / 1,070 (45) / 5,857 (49) / 3,027 (51)
Unknown / 0 / 0 / 3 (0.1)
Comorbid asthma (at any time), n (%) / 423 (18) / 2,394 (20) / 1,239 (21)
Exacerbation rate during the year prior to and including the initial date of COPD diagnosis, n (%)
0 / 1,492 (62) / 7,274 (61) / 3,381 (57)
1 / 541 (23) / 2,835 (24) / 1,443 (25)
2 / 180 (7.5) / 983 (8.3) / 537 (9.1)
≥3 / 178 (7.4) / 789 (6.6) / 521 (8.9)
Lung function, n (%)
Grade 1 (mild: FEV1 ≥80% predicted) / 336(14) / 1,798 (15) / 878 (15)
Grade 2 (moderate: 50% ≤ FEV180% predicted) / 1,144 (48) / 6,462 (54) / 3,471 (59)
Grade 3 (severe: 30% ≤ FEV150% predicted) / 738 (31) / 3,040 (26) / 1,312 (22)
Grade 4 (very severe: FEV130% predicted) / 173 (7.2) / 581 (4.9) / 221 (3.8)
mMRC score, n (%)
Unknown / 1,074 (45) / 2,553 (21) / 342 (5.8)
0–1 / 653 (27) / 5,172 (44) / 3,546 (60)
2+ / 664 (28) / 4,156 (35) / 1, 994 (34)

Of the total study population, 2,219 (11%) patients did not have a recorded mMRC score in their medical records so their data were obtained through questionnaires

Table S2. Presence of comorbidities in the overall study population (N = 20,154)

Comorbidity / n (%)
Depression/anxiety / 6,319 (31)
Asthma / 4,056 (20)
Ischaemic heart disease / 3,577 (18)
Diabetes / 3,526 (17)
Chronic kidney disease / 3,511 (17)
Osteoporosis / 2,690 (13)
Rhinitis / 2,493 (12)
Gastroesophageal reflux disease / 2,375 (12)
Heart failure / 1,511 (7.5)
Chronic renal failure / 216 (1.1)

Table S3. Factors predictive of any initial therapy and initial maintenance therapy (long-acting agents; ICS with/without long-acting agents; theophylline): univariable analysis

Patients (n) / Odds of being prescribed any initial therapy versusno therapy / Odds of being prescribed initial maintenance therapy versus
short-acting or no therapy
OR (95% CI) / P value / Overall
P value* / OR
(95% CI) / P value / Overall
P value*
All patients, including those treated at or up to 1 year before COPD diagnosis
Year of COPD diagnosis (reference category: 1997–2001 [n=2,391])
2002–2006 / 11,881 / 1.30
(1.18, 1.43) / 0.001 / 0.001 / 1.20
(1.10, 1.31) / 0.001 / 0.001
2007–2010 / 5,882 / 1.38
(1.24, 1.53) / 0.001 / 1.10
(1.00, 1.21) / 0.059
Comorbid asthma diagnosis (reference category: NO [n=16,098])
YES / 4,056 / 4.08
(3.67, 4.54) / 0.001 / 0.001 / 5.49
(5.06, 5.96) / 0.001 / 0.001
Lung function grade
(reference category: 2 [n=11,077])
1 / 3012 / 0.89
(0.82, 0.97) / 0.011 / 0.001 / 0.96
(0.88, 1.04) / 0.307 / 0.001
3 / 5,090 / 1.09
(1.01, 1.18) / 0.026 / 1.20
(1.12, 1.28) / 0.001
4 / 975 / 1.04
(0.90, 1.20) / 0.610 / 1.23
(1.08, 1.40) / 0.002
mMRC score
(reference category: 0 [n=2,234])
1 / 7,137 / 1.21
(1.09, 1.34) / 0.001 / 0.001 / 1.18
(1.07, 1.29) / 0.001 / 0.001
2 / 4,003 / 1.27
(1.13, 1.43) / 0.001 / 1.29
(1.17, 1.43) / 0.001
3 / 2,232 / 1.33
(1.17, 1.52) / 0.001 / 1.35
(1.20, 1.51) / 0.001
4 / 579 / 1.39
(1.12, 1.71) / 0.002 / 1.56
(1.30, 1.88) / 0.001
Annual exacerbation rate
(reference category: 0 [n=12,147])
1 / 4,819 / 2.44
(2.25, 2.64) / 0.001 / 0.001 / 1.68
(1.57, 1.80) / 0.001 / 0.001
2 / 1,700 / 3.94
(3.40, 4.58) / 0.001 / 2.70
(2.43, 3.00) / 0.001
≥3 / 1,488 / 6.08
(5.04, 7.33) / 0.001 / 4.82
(4.25, 5.47) / 0.001
GOLD Group
(reference category: A [n=6,390])
B / 3,900 / 1.14
(1.05, 1.25) / 0.003 / 0.001 / 1.14
(1.05, 1.24) / 0.001 / 0.001
C / 2,981 / 1.54
(1.39, 1.71) / 0.001 / 1.66
(1.52, 1.81) / 0.001
D / 2,914 / 1.51
(1.36, 1.67) / 0.001 / 1.79
(1.64, 1.96) / 0.001
GOLD Group
(reference category: C [n=2,981])
A / 6,390 / 0.65
(0.59, 0.72) / 0.001 / 0.001 / 0.60
(0.55, 0.66) / 0.001 / 0.001
B / 3,900 / 0.74
(0.66, 0.83) / 0.001 / 0.69
(0.63, 0.76) / 0.001
D / 2,914 / 0.98
(0.87, 1.11) / 0.737 / 1.08
(0.97, 1.20) / 0.142
GOLD Group
(reference category: A/B [n=10,290])
C/D / 5,895 / 1.45
(1.35, 1.57) / 0.001 / 0.001 / 1.64
(1.54, 1.75) / 0.001 / 0.001
Subgroup of patients, excluding those treated before COPD diagnosis
Year of COPD diagnosis
(reference category: 1997–2001
[n=996])
2002–2006 / 4,451 / 1.37
(1.16, 1.61) / 0.001 / 0.001 / 1.57
(1.19, 2.06) / 0.001 / 0.001
2007–2010 / 2,332 / 1.90 (1.60, 2.26) / 0.001 / 2.40
(1.81, 3.18) / 0.001
Comorbid asthma diagnosis (reference category: NO [n=7,229])
YES / 550 / 0.78
(0.64, 0.95) / 0.015 / 0.015 / – / – / NS
Lung function grade
(reference category: 2 [n=4,336])
1 / 1,201 / 0.79
(0.68, 0.92) / 0.002 / 0.015 / 0.88
(0.70, 1.10) / 0.252 / 0.001
3 / 1,870 / 1.00
(0.89, 1.12) / 0.970 / 1.23
(1.03, 1.46) / 0.020
4 / 372 / 1.01
(0.80, 1.27) / 0.947 / 1.61
(1.19, 2.17) / 0.002
mMRC score
(reference category: 0 [n=921])
1 / 2,671 / 1.15
(0.97, 1.36) / 0.102 / 0.040 / 1.10
(0.85, 1.42) / 0.460 / 0.021
2 / 1,506 / 1.32
(1.10, 1.58) / 0.003 / 1.22
(0.93, 1.60) / 0.153
3 / 796 / 1.24
(1.01, 1.53) / 0.043 / 1.42
(1.05, 1.93) / 0.022
4 / 202 / 1.28
(0.92, 1.78) / 0.144 / 1.80
(1.17, 2.79) / 0.008
Annual exacerbation rate
(reference category: 0 [n=5,827])
1 / 1,432 / 1.75
(1.54, 1.97) / 0.001 / 0.001 / 1.50
(1.26, 1.79) / 0.001 / 0.001
2 / 338 / 1.77
(1.41, 2.23) / 0.001 / 1.79
(1.31, 2.43) / 0.001
≥3 / 182 / 1.34
(0.98, 1.85) / 0.067 / 1.28
(0.81, 2.04) / 0.293
GOLD Group
(reference category: A [n=2,650])
B / 1,577 / 1.26
(1.10, 1.44) / 0.001 / 0.007 / 1.22
(1.00, 1.50) / 0.051 / 0.001
C / 942 / 1.19
(1.01, 1.39) / 0.039 / 1.33
(1.05, 1.69) / 0.017
D / 927 / 1.15
(0.98, 1.35) / 0.097 / 1.55
(1.24, 1.95) / 0.001
GOLD Group
(reference category: C [n=942])
A / 2,650 / 0.84
(0.72, 0.99) / 0.039 / 0.007 / 0.75
(0.59, 0.95) / 0.017 / 0.001
B / 1,577 / 1.06
(0.89, 1.26) / 0.507 / 0.92
(0.71, 1.18) / 0.505
D / 927 / 0.97
(0.80, 1.18) / 0.751 / 1.16
(0.89, 1.52) / 0.142
GOLD Group
(reference category: A/B [n=4,227])
C/D / 1,869 / 1.07
(0.95, 1.20) / 0.269 / 0.269 / 1.33
(1.13, 1.57) / 0.001 / 0.001

Lung function grades are defined as: 1: ≥80% predicted; 2: 50% ≤ FEV180% predicted; 3: 30% ≤ FEV150% predicted; 4: FEV130% predicted.5

*Chi-square test.

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 second; ICS, inhaled corticosteroid; GOLD, Global initiative for chronic Obstructive Lung Disease; mMRC, modified Medical Research Council; OR, odds ratio.

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Figure S1. Study diagram (including inclusion and exclusion criteria).

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COPD, chronic obstructive pulmonary disease; QOF, Quality and Outcomes Framework.

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