Prevalence of Poorly Controlled Asthma and Factors Associated with Specialist Referral in Those with Poorly Controlled Asthma in a Paediatric Asthma Population

Figures & data

Table 1 Baseline Characteristics of the Study Population, by Age Cohort

Characteristic	6–11 Years			12–17 Years
	All Subjects N (% of Total)	With Poor Control N (% of Total)	Without Poor Control N (% of Total)	All Subjects N (% of Total)	With Poor Control N (% of Total)	Without Poor Control N (% of Total)
Total	93,961 (100%)	14,817 (15.8%)	79,144 (84.2%)	91,029 (100%)	15,176 (16.7%)	75,853 (83.3%)
Age, years (median, IQR)	7 (6–9)	7 (7–9)	8 (7–9)	13 (12–14)	13 (13–14)	14 (13–15)
Male	57,362 (61.0%)	9418 (63.6%)	47,944 (60.6)	52,549 (57.7%)	8975 (59.1%)	43,574 (57.5%)
BMI (kg/m^2)
Underweight	5692 (6.1%)	1029 (6.9%)	4663 (6.0%)	4933 (5.4%)	873 (5.7%)	4060 (5.3%)
Healthy weight	35,242 (37.5%)	5894 (39.8%)	29,348 (37.1%)	33,412 (36.7%)	5731 (37.8%)	27,681 (36.5%)
Overweight	9281 (9.9%)	1660 (11.2%)	7621 (9.6%)	12,532 (13.8%)	2444 (16.1%)	1088 (13.3%)
Obese	5026 (5.4%)	982 (6.6%)	4044 (5.1%)	5684 (6.2%)	1192 (7.9%)	4492 (5.9%)
Missing	38,720 (41.2%)	5252 (35.5%)	3468 (42.3%)	34,468 (37.9%)	4936 (32.5%)	29,532 (38.9%)
Socioeconomic status (IMD quintile)
1 (least deprived)	19,208 (20.4%)	2361 (15.9%)	16,847 (21.3%)	19,010 (20.9%)	2527 (16.7%)	16,483 (21.7%)
2	17,118 (18.2%)	2356 (16.0%)	14,762 (18.7%)	16,827 (18.5%)	2639 (17.4%)	14,188 (18.7%)
3	16,715 (17.8%)	2533 (17.1%)	14,182 (17.9%)	16,554 (18.2%)	2712 (17.9%)	13,842 (18.4%)
4	18,675 (19.9%)	3251 (21.9%)	15,424 (19.5%)	18,056 (19.8%)	3207 (21.1%)	14,849 (19.6%)
5 (most deprived)	22,183 (23.6%)	4299 (29.0%)	17,884 (22.6%)	20,503 (22.5%)	4085 (26.9%)	16,418 (21.6%)
Missing	62 (0.07%)	17 (0.11%)	45 (0.06%)	79 (0.09%)	6 (0.04%)	73 (0.10%)
Asthma treatment (GINA step)
GINA step 0–3	91,891 (97.8%)	13,954 (94.2%)	77,937 (98.5%)	85,632 (94.1%)	13,034 (85.9%)	72,598 (95.7%)
GINA step 4+5	2070 (2.2%)	863 (5.8%)	1207 (1.5%)	5397 (5.9%)	2142 (14.1%)	3255 (4.3%)
Comorbidities
Allergic rhinitis/hay fever	16,587 (17.7%)	2896 (19.6%)	13,691 (17.3%)	27,001 (29.7%)	4970 (32.8%)	22,031 (29.0%)
Eczema	49,463 (52.6%)	8724 (58.9%)	40,739 (51.5%)	45,725 (50.2%)	8549 (56.3%)	37,176 (49.0%)
Food allergy	6161 (6.6%)	1355 (9.1%)	4806 (6.1%)	5279 (5.8%)	1248 (8.2%)	4031 (5.3%)

Notes: Percentage of the total number of children with and without poor control (ie, row percentages). The remaining percentages are column percentages.

Abbreviations: IQR, interquartile range; GINA, Global Initiative for Asthma.

Table 2 Odds Ratios for Selected Risk Factors for Poor Control in a Paediatric Asthma Population (Aged 6–17 Years)

Risk Factor	Unadjusted OR	95% CI	p-value	Adjusted OR	95% CI	p-value
Gender
Male (baseline)	0.00	–	–	0.00	–	–
Female	0.92	0.90–0.95	< 0.001	0.94	0.91–0.97	< 0.001
Age (years)	0.98	0.98–0.99	< 0.001	0.97	0.97–0.98	< 0.001
BMI
Healthy weight	0.00	–	--	0.00	–	--
Underweight	1.07	1.01–1.13	0.016	1.06	1.01–1.13	0.026
Overweight	1.15	1.11–1.20	< 0.001	1.13	1.08–1.18	< 0.001
Obese	1.27	1.20–1.33	< 0.001	1.19	1.13–1.26	< 0.001
IMD quintile
1 (baseline)	0.00	–		0.00	–
2	1.18	1.13–1.23		1.19	1.12–1.25
3	1.29	1.23–1.34		1.31	1.24–1.38
4	1.48	1.42–1.54		1.49	1.42–1.57
5 (most deprived)	1.70	1.63–1.77	< 0.001	1.73	1.65–1.82	< 0.001
GINA steps
1–3 (baseline)	0.00	–		0.00	–
4 + 5	3.94	3.75–4.14	< 0.001	3.79	3.57–4.03	< 0.001
Food allergy
No (baseline)	0.00	–		0.00	–
Yes	1.59	1.51–1.67	< 0.001	1.41	1.33–1.50	< 0.001
Eczema
No (baseline)	0.00	–		0.00	–
Yes	1.33	1.30–1.37	< 0.001	1.26	1.22–1.30	< 0.001
Allergic rhinitis
No (baseline)	0.00	–		0.00	–
Yes	1.18	1.15–1.22	< 0.001	1.13	1.09–1.17	< 0.001

Notes: Adjusted for age, gender, BMI and deprivation quintile, GINA step and atopic comorbidities (eczema, food allergy, allergic rhinitis). Adjusted ORs are based on a complete case analysis (n= 111,725 observations and 98,497 unique individuals). Age (at index date) was modelled as a continuous variable. BMI: body mass index. IMD: index of multiple deprivation. GINA: Global Initiative for Asthma. GINA baseline category includes children and adolescents on SABAs only.

Abbreviations: OR, odds ratio; CI, confidence interval.

Table 3 Characteristics of Children and Adolescents with Poorly Controlled Asthma, by 12-Month Referral Status, by Age Cohort (6–11 and 12–17 Years)

Characteristic	6–11 Years			12–17 Years
	All N (% of Total)	Referral N (% of Total)	Non-Referral N (% of Total)	All N (% of Total)	Referral N (% of Total)	Non-Referral N (% of Total)
Total	13,222 (100%)	292 (2.2%)	12,930	13,789 (100%)	238 (1.7%)	13,551
Age, years (median, IQR)	7 (7–8)	7 (7–8)	7 (7–8)	13 (13–14)	13 (13–14)	13 (13–14)
Male	8415 (63.6%)	181 (62.0%)	8234 (63.7%)	8218 (59.6%)	119 (50.0%)	8099 (57.5%)
BMI (kg/m^2)
Underweight	913 (6.9%)	17 (5.8%)	896 (6.9%)	773 (5.6%)	16 (6.7%)	757 (5.6%)
Healthy weight	5260 (39.8%)	120 (41.1%)	5140 (39.8%)	5207 (37.8%)	102 (42.9%)	5105 (37.7%)
Overweight	1460 (11.0%)	36 (12.3%)	1424 (11.0%)	2219 (16.1%)	36 (15.1%)	2219 (16.4%)
Obese	874 (6.6%)	17 (5.8%)	857 (6.5%)	1084 (7.9%)	17 (7.1%)	1067 (7.9%)
Missing	4715 (35.7%)	102 (34.9%)	4613 (35.7%)	4406 (32.7%)	102 (28.2%)	4439 (32.8%)
Socioeconomic status (IMD quintile)
1 (least deprived)	2132 (16.1%)	34 (11.6%)	2098 (16.2%)	2303 (16.7%)	31 (13.0%)	2272 (16.8%)
2	2106 (15.9%)	39 (13.4%)	2067 (16.0%)	2397 (17.4%)	47 (19.8%)	2350 (17.4%)
3	2244 (17.0%)	50 (17.1%)	2194 (17.0%)	2466 (17.9%)	31 (13.0%)	2435 (18.0%)
4	2895 (21.9%)	80 (27.4%)	2815 (21.8%)	2925 (21.2%)	53 (22.3%)	2872 (21.2%)
5	3832 (29.0%)	89 (30.5%)	3743 (29.0%)	3692 (26.8%)	76 (31.9%)	3616 (26.7%)
Missing	13 (<0.01%)	0 (0)	13 (<0.01%)	6 (<0.01%)	0 (0)	6 (<0.01%)
Disease severity
GINA step 0–3	12,472 (94.3%)	238 (81.5%)	12,234 (94.6%)	11,858 (86.0%)	129 (54.2%)	11,729 (86.6%)
GINA step 4+5	750 (5.7%)	54 (18.5%)	696 (5.4%)	1822 (13.5%)	109 (45.8%)	1931 (14.0%)
Comorbidities
Allergic rhinitis/hay fever	2487 (19.2%)	64 (21.9%)	2551 (19.3%)	4523 (32.8%)	88 (37.0%)	4435 (32.7%)
Eczema	2551 (19.3%)	107 (36.6%)	2487 (19.2%)	7820 (56.7%)	146 (61.3%)	7674 (56.6%)
Food allergy	1208 (9.1%)	41 (14.4%)	1167 (9.0%)	1113 (8.1%)	33 (13.9%)	1080 (8.0%)
Components of poor control
≥ 6 SABA inhalers	7824 (59.2%)	179 (61.3%)	7645 (59.1%)	9875 (71.6%)	179 (75.2%)	9696 (71.6%)
≥ 2 OCS courses	2562 (19.1%)	89 (30.5%)	2473 (19.4%)	1533 (11.1%)	75 (31.5%)	1458 (10.8%)
cACT or ACT<20	590 (4.6%)	7 (2.4%)	597 (4.5%)	632 (4.6%)	10 (4.2%)	622 (4.6%)
≥ 1 hospital admission	3932 (30.4%)	135 (46.2%)	4067 (30.8%)	3453 (25.1%)	105 (44.1%)	3351 (24.7%)
≥ 1 A&E visit	1187 (9.2%)	46 (15.8%)	1233 (9.3%)	697 (5.1%)	36 (15.1%)	661 (4.9%)

Notes: Percentage of the total number of children who were referred (ie row percentages). The remaining percentages are column percentages. GINA baseline category (0–3) includes children and adolescents on SABAs only.

Abbreviations: SABA, short-acting beta agonists; OCS, oral corticosteroid; cACT, children’s asthma control test; IQR, interquartile range; BMI, body mass index; IMD, Index of Multiple Deprivation; GINA, Global Initiative for Asthma.

Table 4 Factors Associated with Referral to a Respiratory Specialist Among Children and Adolescents with Poorly Controlled Asthma (6–17 Years)

Risk Factor	Unadjusted HR	95% CI	p-value	Adjusted HR	95% CI	p value
Disease severity
GINA steps
1–3 (baseline)	0.00	–		0.00	–
4 + 5	4.04	3.35–4.87	< 0.001	2.72	2.13–3.49	< 0.001
Gender
Male (baseline)	0.00	–	–	0.00	–	–
Female	1.25	1.05–1.48	0.012	1.17	0.95–1.44	0.141
Age (years)	0.95	0.92–0.98	< 0.001	0.95	0.91–0.98	0.006
BMI
Healthy weight	0.00	–	--	0.00	–	–
Underweight	0.91	0.63–1.31	0.618	0.93	0.65–1.35	0.718
Overweight	0.93	0.71–1.21	0.570	0.92	0.70–1.20	0.527
Obese	0.82	0.57–1.17	0.278	0.79	0.55–1.13	0.188
IMD quintile
1 (baseline)	0.00	–		0.00	–
2	1.30	0.94–1.79	0.114	1.24	0.82–1.85
3	1.18	0.85–1.64	0.314	1.25	0.84–1.87
4	1.56	1.16–2.11	0.003	1.45	1.00–2.11
5 (most deprived)	1.52	1.14–2.02	0.005	1.57	1.10–2.24	0.031
Food allergy
No (baseline)	0.00	–		0.00	–
Yes	1.72	1.34–2.20	< 0.001	1.42	1.01–1.94	0.026
Eczema
No (baseline)	0.00	–		0.00	–
Yes	1.18	0.99–1.41	0.063	1.05	0.84–1.33	0.656
Allergic rhinitis
No (baseline)	0.00	–		0.00	–
Yes	1.13	0.94–1.37	0.195	1.25	1.00–1.57	0.051
≥ 6 SABA inhalers	1.08	0.90–1.30	0.397	1.84	1.42–2.37	< 0.001
≥ 2 OCS courses	2.48	2.06–2.98	< 0.001	2.18	1.70–2.79	< 0.001
cACT or ACT<20	0.72	0.44–1.17	0.183	1.52	0.90–2.56	0.118
≥ 1 hospital admission	2.16	1.82–2.56	< 0.001	2.51	1.97–3.19	< 0.001
≥ 1 A&E visit	2.45	1.93–3.11	< 0.001	1.77	1.30–1.41	< 0.001

Notes: Adjusted for age, gender, BMI and deprivation quintile, GINA treatment step, atopic comorbidities (eczema, food allergy, allergic rhinitis) and the individual poor control criteria, using a complete case analysis (number of observations = 17,779). This category includes children and adolescents on SABAs only. Age (at index date) was modelled as a continuous variable.

Abbreviations: GINA, Global Initiative for Asthma; BMI, body mass index; IMD, Index of Multiple Deprivation; SABA, short-acting beta agonists; OCS, oral corticosteroid; cACT, children’s asthma control test.