Table 1

Characteristics of the eligible study population, stratified by enrolment to the CO@h programme

	Not enrolled		Enrolled		P value*
	Number	Percentage	Number	Percentage	P value*
Age category (years)
18–49	36 037	56.0%	328	44.1%	<0.001
50–64	17 871	27.8%	279	37.6%
65–79	7267	11.3%	107	14.4%
80 or more	3130	4.9%	29	3.9%
Sex
Female	34 282	53.3%	378	50.9%	<0.001
Male	27 644	43.0%	365	49.1%
Missing	2379	3.7%	0	0.0%
Ethnicity
Asian/Asian British	11 543	18.0%	116	15.6%	0.002
Black/African/Caribbean/Black British	3710	5.8%	20	2.7%
Mixed/multiple ethnic groups	1428	2.2%	11	1.5%
Other ethnic group	2791	4.3%	29	3.9%
White	41 797	65.0%	535	72.0%
Missing	77	0.1%	1	0.1%
IMD tertile
1 (most deprived)	28 695	44.6%	379	51.0%	0.002
2	20 471	31.8%	227	30.6%
3 (least deprived)	15 062	23.4%	136	18.3%
Missing	77		1
Body mass index
Underweight	1281	2.0%	†	†	<0.001†
Healthy weight	14 461	22.5%	115†	15.5%†
Overweight	18 902	29.4%	230†	31.0%†
Obese	21 920	34.1%	320†	43.1%†
Missing	7741	12.0%	80†	10.8%†
CEV
Not CEV	54 832	85.3%	627	84.4%	0.501
CEV	9473	14.7%	116	15.6%	0.501
Smoking status
Never smoker	37 445	58.2%	410	55.2%	0.015
Ex-smoker	14 295	22.2%	200	26.9%
Current smoker	9431	14.7%	105	14.1%
Missing	3134	4.9%	28	3.8%
Comorbidities
Hypertension	12 958	20.2%	181	24.4%	0.004
Chronic cardiac disease	5269	8.2%	67	9.0%	0.416
Chronic kidney disease	640	1.0%	†	†	>0.5†
Chronic respiratory disease	17 557	27.3%	257	34.6%	<0.001
Dementia	554	0.9%	†	†	0.05–0.5†
Diabetes	8955	13.9%	127	17.1%	0.013
Chronic neurological disease (including epilepsy)	2739	4.3%	35	4.7%	0.545
Learning disability	462	0.7%	†	†	>0.5†
Malignancy or immunosuppression	6448	10.0%	73	9.8%	0.855
Severe mental illness	2122	3.3%	19	2.6%	0.259
Peripheral vascular disease	555	0.9%	10	1.3%	0.158
Stroke or TIA	1772	2.8%	23	3.1%	0.574
Month of COVID-19 test
September/October	6673	10.4%	†	†	<0.001†
November	8877	13.8%	†	†
December	14 584	22.7%	30†	4.0%†
January	23 211	36.1%	405†	54.5%†
February	6944	10.8%	200†	26.9%†
March	2731	4.2%	75†	10.1%†
April/May	1285	2.0%	20†	2.7%†
Days from ED attendance to COVID-19 test
−3 to −1 days	11 504	17.9%	35	4.7%	<0.001
0–4 days	29 003	45.1%	354	47.6%
5–10 days	19 311	30.0%	300	40.4%
Total	64 305		743

*P value from χ² test comparing proportions not enrolled to enrolled.
†Small values for non-missing data suppressed, and remaining values for variable rounded to nearest 5; values of p reported as, <0.001, <0.05, 0.05–0.5, or>0.5.
CEV, clinically extremely vulnerable; CO@h, COVID-19 Oximetry @home; IMD, Index of Multiple Deprivation; TIA, transient ischaemic attack.