Between-practice variation in chronic obstructive pulmonary disease diagnosis guideline compliance: an observational study

Alex Bottle; Alex Adamson; Benedict Hayhoe; Jennifer K Quint

doi:10.3399/BJGPO.2024.0263

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Figure 1. Funnel plot of proportion of patients following the initial NICE pathways (performed spirometry within 6 months before and after COPD diagnosis) by number of COPD patients per practice. COPD = chronic obstructive pulmonary disease. GOLD = Global Initiative for Chronic Obstructive Lung Disease. NICE = National Institute for Health and Care Excellence.

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Table 1. Patient characteristics

Variable		2006–2007, n = 31 676, n (%)^a	2016–2017, n = 37 393, n (%)^a	March–August 2020, n = 3368, n (%)^a	Total, n (%)^a
Sex	Female	14 583 (46.0)	17 196 (46.0)	1591 (47.2)	33 370 (46.1)
Sex	Male	17 093 (54.0)	20 197 (54.0)	1777 (52.8)	39 069 (53.9)
Age, years	Mean (SD)	67.5 (11.3)	66.5 (11.4)	66.4 (11.7)	68.3 (12.0)
IMD quintile	1 (least deprived)	4692 (14.8)	5508 (14.7)	468 (13.9)	10 668 (14.7)
	2	5684 (17.9)	6544 (17.5)	559 (16.6)	12 787 (17.7)
	3	5968 (18.8)	6932 (18.5)	648 (19.2)	13 548 (18.7)
	4	6683 (21.1)	8181 (21.9)	762 (22.6)	15 626 (21.6)
	5 (most deprived)	8621 (27.2)	10 208 (27.3)	929 (27.6)	19 758 (27.3)
	Missing	28 (0.1)	20 (0.1)	<5 (0.1)	NA (0.1)
Smoking status	Missing	776 (2.4)	2129 (5.7)	115 (3.4)	3020 (4.2)
	Never smoker	3599 (11.4)	3734 (10.0)	349 (10.4)	7682 (10.6)
	Ex-smoker	12 306 (38.8)	13 978 (37.4)	1345 (39.9)	27 629 (38.1)
	Current smoker	14 995 (47.3)	17 552 (46.9)	1559 (46.3)	34 106 (47.1)
BMI measured	Yes	28 917 (91.3)	36 430 (97.4)	3272 (97.1)	68 619 (94.7)
BMI measured	No	2759 (8.7)	963 (2.6)	96 (2.9)	3818 (5.3)
BMI category	Underweight (<18.5 kg/m²)	1413 (4.5)	1473 (3.9)	130 (3.9)	3016 (4.2)
	Normal (18.5–24.9 kg/m²)	10 905 (34.4)	12 185 (32.6)	1119 (33.2)	24 209 (33.4)
	Overweight (25.0–29.9 kg/m²)	9762 (30.8)	12 223 (32.7)	1010 (30.0)	22 995 (31.7)
	Obese (≥30 kg/m²)	6837 (21.6)	10 549 (28.2)	1013 (30.1)	18 399 (25.4)
	Missing	2759 (8.7)	963 (2.6)	96 (2.9)	3818 (5.3)
Current asthma	Yes	8170 (25.8)	7356 (19.7)	672 (20.0)	16 198 (22.4)
Congestive heart failure	Yes	2008 (6.3)	2383 (6.4)	286 (8.5)	4677 (6.5)
Total number of comorbidities	Mean (SD)	3.5 (1.9)	4.2 (2.1)	4.2 (2.3)	3.9 (2.2)
GOLD status	GOLD stage 1: ≥80%	2748 (8.7)	8516 (22.8)	848 (25.2)	12 112 (16.7)
	GOLD stage 2: 50%–79%	11 722 (37.0)	15 839 (42.4)	913 (27.1)	28 474 (39.3)
	GOLD stage 3: 30%–49%	4927 (15.6)	4066 (10.9)	217 (6.4)	9210 (12.7)
	GOLD stage 4:<30%	819 (2.6)	502 (1.3)	26 (0.8)	1347 (1.9)
	Missing FEV1 %-predicted measurement	11 460 (36.2)	8470 (22.7)	1364 (40.5)	21 294 (29.4)

^aUnless otherwise stated. BMI = body mass index. FEV1 = forced expiratory volume. GOLD = Global Initiative for Chronic Obstructive Lung Disease. IMD = Index of Multiple Deprivation. NA = not available. SD = standard deviation.

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Table 2. Compliance with NICE guidelines for COPD diagnosis, all patients

Variable		2006–2007, n (%)	2016–2017, n (%)	March–August 2020, n (%)	Total, n (%)	P-value
Spirometry (pre-diagnosis)	Yes	25 472 (62.8)	35 800 (74.2)	2902 (61.1)	64 174 (68.6)	<0.001
Spirometry (pre-diagnosis)	No	15 105 (37.2)	12 449 (25.8)	1850 (38.9)	29 404 (31.4)
CXR	Yes	19 859 (48.9)	31 138 (64.5)	3186 (67.0)	54 183 (57.9)	<0.001
CXR	No	20 718 (51.1)	17 111 (35.5)	1566 (33.0)	39 395 (42.1)
FBC	Yes	30 470 (75.1)	42 798 (88.7)	4381 (92.2)	77 649 (83.0)	<0.001
FBC	No	10 107 (24.9)	5451 (11.3)	371 (7.8)	15 929 (17.0)
BMI	Yes	36 060 (88.9)	46 321 (96.0)	4555 (95.9)	86 936 (92.9)	<0.001
BMI	No	4517 (11.1)	1928 (4.0)	197 (4.1)	6642 (7.1)
All of spirometry, FBC, CXR, and BMI measurement before COPD diagnosis	Yes	10 811 (26.6)	22 541 (46.7)	2043 (43.0)	35 395 (37.8)	<0.001
	No	29 766 (73.4)	25 708 (53.3)	2709 (57.0)	58 183 (62.2)
At least one of FBC, CXR, and BMI measurement before COPD diagnosis	Yes	39 055 (96.2)	47 536 (98.5)	4684 (98.6)	91 275 (97.5)	<0.001
	No	1522 (3.8)	713 (1.5)	68 (1.4)	2303 (2.5)
Spirometry, CXR, BMI, and FBC	Spirometry and one of CXR, BMI, or FBC	25 128 (61.9)	35 719 (74.0)	2900 (61.0)	63 747 (68.1)	<0.001
	Spirometry only	344 (0.8)	81 (0.2)	2 (0.04)	427 (0.5)
	No spirometry and one of CXR, BMI, or FBC	13 927 (34.3)	11 817 (24.5)	1784 (37.5)	27 528 (29.4)
	No spirometry, CXR, BMI, or FBC	1178 (2.9)	632 (1.3)	66 (1.4)	1876 (2.0)
Spirometry in the year before COPD diagnosis	Yes	23 130 (57.0)	29 800 (61.8)	1657 (34.9)	54 587 (58.3)	<0.001
Spirometry in the year before COPD diagnosis	No	17 447 (43.0)	18 449 (38.2)	3095 (65.1)	38 991 (41.7)
CXR in the year before COPD diagnosis	Yes	9978 (24.6)	16 345 (33.9)	1513 (31.8)	27 836 (29.7)	<0.001
CXR in the year before COPD diagnosis	No	30 599 (75.4)	31 904 (66.1)	3239 (68.2)	65 742 (70.3)
FBC in the year before COPD diagnosis	Yes	19 556 (48.2)	27 222 (56.4)	2666 (56.1)	49 444 (52.8)	<0.001
FBC in the year before COPD diagnosis	No	21 021 (51.8)	21 027 (43.6)	2086 (43.9)	44 134 (47.2)
BMI measurement in the year before COPD diagnosis	Yes	22 917 (56.5)	29 158 (60.4)	2595 (54.6)	54 670 (58.4)	<0.001
BMI measurement in the year before COPD diagnosis	No	17 660 (43.5)	19 091 (39.6)	2157 (45.4)	38 908 (41.6)
All of spirometry, FBC, CXR, and BMI measurement in the year before COPD diagnosis	Yes	2807 (6.9)	5598 (11.6)	366 (7.7)	8771 (9.4)	<0.001
	No	37 770 (93.1)	42 651 (88.4)	4386 (92.3)	84 807 (90.6)
At least one of FBC, CXR, and BMI measurement in the year before COPD diagnosis	Yes	31 892 (78.6)	41 027 (85.0)	3858 (81.2)	76 777 (82.0)	<0.001
	No	8685 (21.4)	7222 (15.0)	894 (18.8)	16 801 (18.0)
	Spirometry and one of CXR, BMI, or FBC	19 943 (49.1)	27 257 (56.5)	1520 (32.0)	48 720 (52.1)
	Spirometry only	3187 (7.9)	2543 (5.3)	137 (2.9)	5867 (6.3)
	No spirometry and one of CXR, BMI, or FBC	11 949 (29.4)	13 770 (28.5)	2338 (49.2)	28 057 (30.0)
	No spirometry, CXR, BMI, or FBC	5498 (13.5)	4679 (9.7)	757 (15.9)	10 934 (11.7)

BMI = body mass index. COPD = chronic obstructive pulmonary disease. CXR = chest X-ray. FBC = full blood count. NICE = National Institute for Health and Care Excellence.

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Table 3. Between-practice variation in compliance with NICE guidelines for COPD diagnosis

Variable	2006–2007, median % (IQR)	2016–2017, median % (IQR)	March–August 2020, median % (IQR)	All cohorts, median % (IQR)
Spirometry (pre-diagnosis)	76.9 (61.2–86.6)	86.4 (78.6–93.3)	80.0 (50.0–100.0)	80.7 (72.3–86.7)
CXR	50.0 (27.3–71.0)	73.1 (50.0–85.7)	80.0 (50.0–100.0)	61.5 (43.2–75.6)
FBC	80.0 (66.7–89.3)	94.4 (86.7–100.0)	100.0 (100.0–100.0)	87.0 (79.4–92.6)
BMI	95.0 (87.5–100.0)	100.0 (96.7–100.0)	100.0 (100.0–100.0)	96.7 (92.6–100.0)
All of spirometry, FBC, CXR, and BMI measurement before COPD diagnosis	27.8 (11.8–44.4)	54.9 (33.3–69.0)	50.0 (0.0–80.0)	42.9 (27.8–55.6)
At least one of FBC, CXR, and BMI measurement before COPD diagnosis	100.0 (97.4–100.0)	100.0 (100.0–100.0)	100.0 (100.0–100.0)	100.0 (98.4–100.0)
None of spirometry, FBC, CXR, or BMI measurement	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)	0.0 (0.0–0.0)
Spirometry in the year before COPD diagnosis	70.8 (55.0–82.4)	77.8 (66.7–86.4)	50.0 (0.0–78.4)	72.6 (63.5–80.0)
CXR in the year before COPD diagnosis	25.0 (7.7–41.7)	39.2 (10.0–58.2)	25.0 (0.0–57.1)	32.4 (15.9–45.5)
FBC in the year before COPD diagnosis	50.0 (37.5–61.9)	62.5 (47.8–73.1)	60.0 (3.1–100.0)	56.0 (43.8–65.0)
BMI measurement in the year before COPD diagnosis	61.5 (46.2–76.7)	66.8 (51.3–80.0)	60.0 (33.3–100.0)	64.1 (52.6–74.2)
All of spirometry, FBC, CXR, and BMI measurement in the year before COPD diagnosis	4.4 (0.0–12.8)	8.7 (0.0–23.1)	0.0 (0.0–0.0)	9.1 (3.0–17.4)
At least one of FBC, CXR, and BMI measurement in the year before COPD diagnosis	83.8 (75.0–92.9)	90.2 (82.9–96.6)	100.0 (71.4–100.0)	86.4 (80.0–92.0)
None of spirometry, FBC, CXR, or BMI measurement in the year before COPD diagnosis	5.9 (0.0–12.9)	3.3 (0.0–8.2)	0.0 (0.0–16.7)	5.9 (2.7–10.0)

BMI = body mass index. COPD = chronic obstructive pulmonary disease. CXR = chest X-ray. FBC = full blood count. IQR = interquartile range. NICE = National Institute for Health and Care Excellence.

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Table 4. Results of multilevel analysis for use of spirometry around the time of COPD diagnosis

Statistic	2006–2007 cohort	2016–2017 cohort	March–August 2020 cohort
n	31 676	37 393	3368
Median n per practice (IQR)	18 (9–31)	21 (11–35)	2 (1–4)
ICC: null model	0.13	0.08	0.09
Median OR: null model (bootstrap 95% CI)	1.95 (1.89 to 1.98)	1.62 (1.59 to 1.65)	1.72 (1.68 to 1.76)
ICC: COPD patient number as predictor	0.12	0.08	0.09
Median OR: COPD patient number as predictor (bootstrap 95% CI)	1.92 (1.87 to 1.96)	1.67 (1.63 to 1.69)	1.72 (1.68 to 1.76)
OR (number of COPD patients at practice) (95% CI)	1.01 (1.00 to 1.01)	1.00 (1.00 to 1.00)	1.01 (0.98 to 1.03)
P-value (number of COPD patients at practice)	<0.001	0.097	0.605

COPD = chronic obstructive pulmonary disease. ICC = intraclass correlation coefficient. IQR = interquartile range. OR = odds ratio.

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Table 5. Funnel plot outlier practices for spirometry within 6 months before and after COPD diagnosis by cohort

Outlier status	2006–2007 cohort, n (%)	2016–2017 cohort, n (%)
Not an outlier	1057 (75.5)	1144 (80.3)
Over 3 SD above the average	61 (4.4)	47 (3.3)
Between 2 and 3 SD above the average	148 (10.6)	154 (10.8)
Between 2 and 3 SD below the average	92 (6.6)	56 (3.9)
More than 3 SD below the average	42 (3.0)	23 (1.6)
Total number of practices	1400 (100)	1424 (100)

COPD = chronic obstructive pulmonary disease. SD = standard deviation.

Supplementary Data

AB_10.3399BJGPO.2024.0263_supp_v1.pdf -
Supplementary material is not copyedited or typeset, and is published as supplied by the author(s). The author(s) retain(s) responsibility for its accuracy.

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